Climate, Energy and Urbanization (TPD0808039)

Copyright © 2008 City of Phoenix – all rights reserved.

This document was produced for the City of Phoenix, which owns all rights, by Arizona State University. It may be copied and used for educational purposes. Any alteration of its contents or reproduction for sale, in whole or in part, is prohibited without express prior approval of the City of Phoenix.

Climate,EnergyandUrbanizationis available at http://www.asusmart.com/climateandenergyguide as an Adobe PDF file for viewing or printing.

Suggested format for citing this publication:

Carlson, J., Golden, J. 2008. Climate,EnergyandUrbanization:AGuideonStrategies,MaterialsandTechnologiesforSustainableDevelopmentintheDesertPrepared for the City of Phoenix, Arizona, USA.

DISCLAIMER

This guide presents best practices for urban heat island mitigation and high performance building design.They are not intended to be comprehensive or complete in all cases. Responsibility for the technical integrity of the project remains with the architect, engineer, or consultant.

This guide was prepared by Arizona State University and sponsored by the City of Phoenix. Any opinions expressed in the guide do not necessarily reflect those of Arizona State University or the City of Phoenix, and reference to any specific product, service, process, or method does not constitute an implied or expressed recommendation or endorsement. Further, no warranties or representations, expressed or implied, as to the fitness for particular purpose or merchantability of any product, apparatus, or service, or the usefulness, completeness, or accuracy of any processes, methods, or other information contained, described, disclosed, or referred to in this guide is given. No representation that the use of any product, apparatus, process, method, or other information will not infringe on privately owned rights is given and Arizona State University and the City of Phoenix will assume no liability for any loss, injury, or damage resulting from, or occurring in connection with, the use of information contained, described, disclosed, or referred to in this document

Table of Contents

Preface • v

Chapter 1 Urban Sustainability in a Desert Region • 1 ntroduction • 3

The Built Environment • 3 Urban Areas • 4

Sustainable Development • 6

Rapid Urbanization In a Desert Region • 8

Urban Environmental Problems • 11

Overconsumption of Resources • 13

ENERGY     3

WATER    23

RESOURCE USE    26

Waste,Emissions andDegraded Energy•27

SOLID WASTE    27

WATER QUALITY    32

AIR QUALITY    34

NOISE POLLUTION    4

URBAN CLIMATE CHANGE    43

Transportation in UrbanAreas • 51

Summary • 52

Additional Resources • 53 References • 55

Chapter 2 Urban Heat Island Mitigation • 60 ntroduction • 62

Land inTransition • 62

Thermal Performance of Urban Materials • 64

Urban Heat Island Mitigation Strategies • 69

Roofing • 69

Pavements • 9

Urban Forestry • 113 Additional Resources • 127 References • 128

Chapter 3 Design for Climate and Energy • 131 ntroduction • 133

Types of Buildings • 134

Evaluating the Environmental Impact of Buildings • 135 Fundamentals of Sustainable Building Design • 135

TechnicalStrategies • 140

Site Selection and Design • 141 Passive Solar Design • 148

Mechanical and Electrical Systems • 156

BuildingLighting,Equipment,EnergyManagement,andUtilities•161Water Management and Conservation • 165

Materials and Product Selection • 167 Additional Resources • 172 References • 172

Chapter 4 Systems, Materials and Technologies • 173 Product Categories

ALTERNATIVE PAVEMENTS • 179

PASSIVE SOLAR DESIGN • 197

BUILDING ENVELOPE:THERMAL AND MOISTURE PROTECTION • 206

BUILDING ENVELOPE: OPENINGS • 233 ELECTRIC AND NATURAL LIGHTING • 252 HEATING AND COOLING SYSTEMS • 277 ONSITE ENERGY GENERATION • 304 WATER USE AND CONSERVATION • 32

VENTILATION AND INDOOR ENVIRONMENTAL QUALITY • 334

BUILDING AUTOMATION • 349

SERVICES • 358

v

Preface

In this guidebook, we hope to increase understanding of the issues of urban development and the opportunities available to lessen urban environmental impact. Phoenix, Las Vegas and Albuquerque, the three largest urban centers in the Desert Southwest, have experienced rapid change and growth over the last decades. This growth has resulted in doubling or tripling the amount of urban infrastructure – roads, parking lots, buildings and utilities – constructed.

‘Urban Sustainability’ is a concept that recognizes the interdependence of the human-built and natural systems and the negative consequences of not matching urban resource consumption to local conditions.These consumption patterns have as much to do with the design and planning of our cities as they do with our individual choices and lifestyles. Design choices

and policies that govern how we build our cities today will lock in the way we will consume energy, water and other resources and determine the quality of life for generations to come. Vulnerability, adaptability and flexibility to respond to shortages and changes in our resource needs must be factored early into the planning process. To make this change in planning our cities a reality, one needs to be knowledgeable about the leading issues and what options there are for development projects.

Sustainability in the Desert Southwest, more than any other region, is strongly influenced by our relationship to the sun. Solar heat gain impacts our energy and water use in buildings and also causes changes to the urban microclimate. Climate Energy and Urbanization looks at the materials from which we construct our cities – the ‘built environment’ as termed in this guide – and the resultant increase in average minimum temperatures known as ‘Urban Heat Island’ effect. Many cities are experiencing this urban phenomenon that spirals the use of energy and water to compensate for increases in urban temperatures, and it is particularly evident in arid urban regions.

Urban heat islands directly affect all three imperatives of sustainable development. It alters weather patterns, increases air pollution formation and energy and water consumption, impacts the durability of roads and other materials, and degrades thermal comfort, agricultural production and vehicle efficiency, all of which impacts business and tourism.This guidebook

suggests cost effective measures and strategies that city planners can implement to immediately address this problem, as well as suggestions for implementing policy at the organizational and governmental level.

Each chapter is written on a separate topic to enable readers to select only the section or chapters that pertain to their particular interest or project needs.

Chapter 1: Urban Sustainability in a Desert Region – Introducessustainabilitywithaspecificfocusonthecurrenttrendsofurban environmental problems found in Arizona metropolitan areas

Chapter 2: Urban Heat Island Mitigation – Strategiesandmaterials formitigatingurbanheatislandsandprovidingactionplansforcities to integrate these strategies into development and renovation plans

Chapter 3: Design for Climate and Energy – Keyconcepts andstrategiesforplanninganddesigninghighperformance,sustainablebuildings, specifically focused on energy efficiency and water conservation

Chapter 4: Systems, Products and Materials – Compilationofsummariesprovidinginformationon awiderangeofsystems,productsand materials used for Urban Heat Island mitigation and high performance building design

We hope that the following information will be transferable to other desert environments and that it will start a dialogue on how to approach the issues of urbanization in our unique desert climate.

Chapter 1:

Urban Sustainability in a Desert Region

Chapter 1: Urban Sustainability in a Desert Region

Chapter 1 Table of Contents

Introduction • 3

The Built Environment • 3 Urban Areas • 4

Sustainable Development • 6

Rapid Urbanization In a Desert Region • 8

Urban Environmental Problems • 11

Overconsumption of Resources • 13

ENERGY     3

WATER    23

RESOURCE USE    26

Waste,Emissions andDegraded Energy•27

SOLID WASTE    27

WATER QUALITY    32

AIR QUALITY    34

NOISE POLLUTION    4

URBAN CLIMATE CHANGE    43

Transportation in UrbanAreas • 51

Summary • 52

Additional Resources • 53 References • 55

1

Introduction

As we enter the 21st century, the human population continues to grow at an unprecedented rate. Meeting the needs and wants of our increasing population has heightened the pressure on water, energy, and other natural resources as never before. Recent advances in meteorology, remote sensing, and communications have revealed the uglier side of human population growth. Current consumption and pollution trends are exposing the fragility of the earth’s ecosystems. Issues such as global climate change have gained a level of public awareness and concern unlike any environmental issue heretofore, finding their way to the headlines of all major media sources and spurring bold actions by corporations, governments, and NGOs. Other impacts such as declining fish populations, species extinction, conflicts over mineral, water, and oil reserves, and urban heat island (UHI) are also gaining media attention. It is unclear to what extent can we continue to pressure these earth systems before they reach an irreversible tipping point. Citizens the world-over are demanding change and leadership from their governments. Despite this public awareness and mounting pressure for new policies, there is a lack of focus and full understanding of the problems at hand. Common terms widely used among champions of change are “Sustainability” and “Sustainable Development.” Although the terms seem self-explanatory, it can often mean different things to different people.

This chapter aims to bring clarity to the often cloudy subject of sustainability and sustainable development particular to the Phoenix region. Defining these concepts is the first step in moving the region along a common pathway.There are indicators that can be used to assess the sustainability of metropolitan centers, and we will determine what these indicators reveal about Phoenix, and what insights they might lend in reversing or slowing the negative trends as our region continues to grow and mature.

The Built Environment

The collective of products and processes of human creation defines the built environment. When we think about protecting and restoring the environment, we often envision the sky, forests, free- flowing rivers, and other natural systems. Although these systems might seem untouched, nothing is totally free from human influence and impacts. Nearly all environments in which we interact are products of human activities. Humans have arranged, maintained, or controlled nearly every piece of the earth (Bartuska 2007).

The shear magnitude and complexity of the built environment requires an organizational framework to jumpstart discussion The built environment can be organized into the following seven categories.

Products

…materials and commodities humans use to perform specific tasks. Examples range from graphic symbols for communicating, tools for constructing, materials for building, and machines for communicating and transporting

Interiors

…a grouping of products, enclosed within a structure, created to enhance activities. Examples include living rooms, kitchens, and bathrooms

Structures

…planned groupings of spaces built of products. Houses, schools, factories, and highways are all example of structures, which usually include both interior and exterior forms

Landscapes

…exterior areas and settings. Built landscape spaces are grouped with structures such as courtyards, parks, and gardens. National parks and forests can be considered natural landscapes.

Cities

…a grouping of structures and landscapes that define the economic, social, cultural, and environmental characteristics of a community. The complex and diverse arrangement of structures can be organized into neighborhoods, subdivisions, villages,

Regions

…cities and landscapes grouped together and defined by political, social, economic, or environmental characteristics. This could include multiple cities, multiple counties, and regional groupings such as the Southwest

Earth

…all the components; regions, cities, and landscaped grouped together—the ultimate human artifact

Urban Areas

Urban areas can be defined as areas of increased density of human-created structures. Although the term city or town is often used interchangeably with urban areas, “urban” typically refers to a certain population density. The US Census Bureau defines an urban area as “core census block groups or blocks that have a population density of at least 1,000 people per square mile (386 per square kilometer) and surrounding census blocks that have an overall density of at least 500 people per square mile (193 per square kilometer).”

Within this definition, there are two general categories of urbanization in the US. Urban areas denote areas with 50,000 or more people, while areas under 50,000 people are called urban clusters.The first urbanized areas were designated in the 1950 census, while urban clusters were added in the 2000 census.There are about 1,371 urban areas and urban clusters with more than 10,000 people in the US.

Each urban area is unique, varying in the quality of its infrastructure, resources used in its daily operation, and the resulting environmental impact of its wastes and emissions, all of which define the quality of life in the urban area.The effectiveness and quality of the governing bodies, municipalities, and other local institutions also define the general quality of an urban area.

Developed Vs. Developing Countries

The distribution of wealth generally divides countries into two categories: developed and developing The countries that have made major social, political, and economic progress in recent history are considered developed.These countries have organized, structured economies generally based on services and manufacturing industries. Other characteristics of developed countries include good educational opportunities for its citizens, a high per capita GDP, low population growth rates, and readily available health services. Developing countries, where 75% of the world’s population resides, generally have agrarian- based economies, are experiencing rapid population growth, and have limited or underdeveloped natural resources.

Figure 1-1. Population in urban and rural for major world areas, in 2000. Percentages represent urban areas (UN 2002).

These combined characteristics often result in a lack of basic necessities of life for most residents of developing countries. Over the last 100 years, the world population living in urban areas has increased from 160 million to over 3 billion and is likely to nearly double again by 2025.

In the US alone, rapid urbanization will result in an expansion of the urban built environment to 427 billion ft2 by 2030, an increase of more than 40% since 2000.This rate of urbanization is unprecedented in human history and is happening across the globe (Figure 2-1) with the most dramatic transition from rural to urban is occurring in less-developed countries.

The problems of developing countries are severe and deserve adequate study and attention from the global community. The nature of these problems differs greatly than those of the more developed countries, thus requiring different tools and strategies.

The massive influx of population into urban centers within countries with slow development and/or limited resources has resulted in abject poverty and social inequality. Rural immigrants whose desire for higher incomes and improved quality of life brought them to urban centers are met with the opposite conditions; being forced to scrape an existence in the makeshift shelters with scant infrastructure on the outskirts of cities

An estimated 600 million urban citizens in less developed countries are living where “their lives and health are continually threatened because of the inadequate provision of safe, sufficient water supplies, sanitation, removal of solid and liquid wastes and health care and emergency services” (Cainross et al. 1990).

The priorities for both developed and developing countries should focus on meeting the basic needs of its citizens.These needs can be met by constructing and maintaining appropriate dwellings, energy sources, freshwater supplies, sanitation systems, and educational and health-care services (Devuyst 2001). While this guidebook focuses upon the problems of developed countries, and Phoenix in particular, as we improve our understanding and develop solutions for the problems of developed areas, the more likely these methods will be transferable to other nations.

ResourceConsumption in Urban Areas

Since the industrial revolution, technological advances have improved life in the developed counties. Most of the problems faced by urbanites of the 1800s have been eliminated, creating life standards within developed countries that far exceed those of other, less-developed nations.The higher incomes in urban centers have also adversely resulted in lifestyles that are based on consumption.The UN report, Our Common Future,” states that the world’s wealthiest 25% consume 80% of the world’s economic output (WCED 1987). Overconsumption is a major cause of much of today’s global environmental degradation.

It is estimated that 64% of the world’s economic consumption and pollution can be linked to cities in the richest countries (Santamouris 2000).

Urban areas take up just 2% of the earth’s surface but account for an unbalanced amount of resource usage. For example, urban areas account for about 75% of industrial wood use and 60% of water use (Worldwatch Institute 2002).The extent of urban impacts upon the environment increases not only as population grows but also as per capita demand for resources rises.

Collectively, the materials/building sector accounts for over 20% of the US economy. Activities associated with constructing and using pavements, infrastructure, and buildings consume 65% of electricity, 37% of primary energy, 25% of water supplies, and 30% of all wood and materials.The urban built environment and its occupants generate 35% of solid waste, 36% of carbon dioxide (CO2) and 46% of sulfur dioxide (SO2) emissions, 19% of nitrogen oxides (NO ) and 10% of fine-particulate emissions. Additionally, 75% of the 3.4 billion metric tons of new materials that are used in the US economy are used by the construction industry and, at the end of the 20th century, only 5% of all materials used were renewable.

Sustainable Development

Sustainability is a characteristic of a process or state that can be maintained indefinitely.The term has been recently used to describe the coexistence of human systems with the earth’s ecological system without either system being damaged. Many consider sustainable development as a continuation of the environmental movement that began in the 1960’s with more

of a focus on integration of economic development and the protection and restoration of natural systems.The beginnings of the sustainable development movement can be traced back to the 1960s and Rachel Carson’s book The Silent Spring (1962) in which she brought awareness to the detrimental effects pesticides have on bird populations. In the following years

a number of publications, including Paul Erlich’s Population Bomb (1968) and the Club of Rome’s Limits to Growth (1972) drew attention to global-development issues and natural-resource depletion.The first use of the term “sustainable development” took place when the International Union for the Conservation of Nature published the World Conservation Strategy in 1980.

In 1986, the UN held meetings of the World Commission on Environment and Development to study the dynamics of global- environmental degradation and make recommendations for the long-term viability of human society.The Commission was chaired by Gro Harlem Brundtland, then Prime Minister of Norway.The product of this meeting was their report, Our Common Future” (Bruntland 1987).The Bruntland Report, as it came to be known, was the benchmark for thinking about the global environment, and popularized the term “sustainable development.” At the time, it was defined as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs” (UN with United Nations1987).

Sustainable development encompasses a much broader spectrum of policy issues than simply those relating to the natural environment. With this definition, sustainable development seeks to unite economic, environmental, and social issues – three concepts once thought of as mutually exclusive. For the first time in western society, technological progress

wealth development, and human prosperity did not have to be at odds with the protection and conservation of that natural environment. In support of this concept, the UN has produced several documents, most recently the 2005 World Summit Outcome Document

This report solidified the three components of sustainable development by referring to the “interdependent and mutually reinforcing pillars” of economic development, social development and environmental protection. Each component is as important as the other, and it is at the confluence of these three agendas sustainable development exists.

Figure 1-2. Diagram showing the overlapping pillars of sustainability: social, economic, and environment.

Public organizations are beginning to take into account a broader view of their oversight and policy responsibilities, ranging across social economic, environmental, ethical, cultural, political, and even religious interests. (Hall 2004).

A global blueprint for sustainability, called Agenda 2 , was agreed upon at the United Nations Conference on Environment and Development in 1992, held in Rio de Janeiro and commonly referred to as the Rio Earth Summit. Chapter 28 of Agenda 21 identifies

local authorities as the sphere of governance closest to the people, and calls upon all local authorities to consult with their communities and develop and implement a local plan for sustainability – a “Local Agenda 2 ” (LA21). Many communities around the world have created sustainability programs to meet this call to action. LA21 provides a framework for implementing sustainable development at the local level by building upon existing local government strategies and resources such as land planning, vegetation management plans, and transportation strategies to better integrate environmental economic and social goals.

The Difference between Green Development and Sustainable Development

There is a lot of talk about what it means to be “green.” Marketing slogans are rampant with ‘green products’, ‘green buildings’ and ‘green innovations’. Green development does not necessarily have the same goals as Sustainable Development. The designation ‘green’ usually implies that it prioritizes environmental sustainability over economic and cultural considerations Sustainable development requires that a product, process or policy address each of the three pillars before it is considered

a more ‘sustainable’ option. An example of this can be found in many developing countries or lower income areas of the US: While environmentally preferable products such as bamboo flooring or roof integrated solar power may decrease environmental impact, they are more expensive to purchase and may be financially unattainable for a small business owner in a developing community. In many cases, cutting-edge green facilities would not contribute to overall sustainability if they require high maintenance costs, which may not be sustainable in regions of the world with less financial resources. On the other side of the spectrum, an inexpensive power generator will likely have a lower efficiency, harmful emissions and a much shorter operational life, costing more in terms of energy, health and maintenance than a slightly more expensive and better quality product.This balance of economic, environmental, and social considerations is sometimes difficult to judge without investigating all of the factors. For this reason, government and industry organizations are beginning to offer certification and labeling systems that help to reduce the ambiguity and take the guesswork out of the purchasing equation

LifeCycle Assessment

A life cycle assessment (LCA) is a technique to assess the environmental impact of a given product or service throughtout its lifespan.This method of measuring the environmental impact is also refered to as life cycle analysis, life cycle inventory, ecobalance, cradle-to-grave-analysis, well-to-wheel analysis, and dust-to-dust energy cost. Regardless of terminology, the method can be applied to just about anything in the built environment, including buildings, cities, and even countries. It is a fundamental, data intensive accounting of all the resources used and waste produced over the entire lifetime of a product from material extraction, use and operation to final disposal.

The goal of an LCA is to enable the consumer, designer, or decision maker to determine which choice is least burdensome to the environment and society.The term “life cycle” implies that a thorough and fair assessment of a product has been conducted, reviewing everything from raw material production, manufacture, distribution, use, maintainence and disposal and all intervening transportation steps. A full LCA of a product, service, or company can be daunting, and inaccurate or missing data can greatly sway results and are highly dependant on the cooperation of the supply chain in accurately reporting the energy, wastes, and costs throughout the manufacturing process. For these reasons, the uncertainty of the accuracy in an LCA can be quite large.

The International Standards Organization (ISO) has created a procedure for conducting an LCA.This procedure can be found in ISO 14000s for environmental management. More specifically, ISO sections 14040:2006 and 14044:2006 address Life Cycle Assessment.

Life Cycle Management integrates sustainability and life-cycle assessment thinking into everyday management, planning, and decision-making processes, using various approaches, concepts and tools and operating at either a management system level a program level, or a technical level. Organizations can further deploy each of these systems, programs, and tools in different ways. However, to be effective, the introduction of LCM in an organization must be an upper-management decision and aligned with an organization’s policies and strategy (UNEP 2005)

The entry of LCM concepts into a public entity typically correspond to an organizational function, such as planning, public works, engineering, airport operations and public health or environmental health and safety (EHS). It is often an organization’s department of environment or sustainability who initially suggests implementation of a life cycle management system.

However, in public organizations, many times it is the general public that compels an organization to adopt sustainability approaches to decision making.

The following sections examine the development patterns of the Phoenix metropolitan area, the main urban environmental and sustainable development issues facing the region, and ideas for prioritizing these issues. Emphasis will be given to sustainability in the urban built environment and will lay the groundwork for the strategies presented in this guidebook

Rapid Urbanization

International attention is being paid to sustainable development at a time when urban areas are gaining an estimated 67 million people per year—about 1.3 million every week, during the greatest population increase our planet has ever witnessed. By 2030, approximately 5 billion people are expected to live in urban areas—60% of the projected global population of 8.3 billion (United Nations 2002).

The rapid urbanization of the Phoenix region exemplifies what is occurring around the globe. Arizona has one of the fastest growing populations in the US and the Phoenix area is one of the most rapidly urbanizing regions. As presented in Figure 1-3 rapid urbanization has transitioned native vegetation to manmade materials used for buildings and transportation networks over the years 1912 to 2000.

Figure 1-3. The rapid urbanization of the three-county Phoenix region 1912, 1975, and 2000. Source Maricopa Association of Governments (MAG)

Phoenix has an arid, semitropical climate, with an average of 300 sunny days per year and 89 days during which the temperature reaches or exceeds 100ºF (38ºC). Most of these warmer days occur from early June through early September.

In 2007, beginning on April 24th, there were 112 days during which Phoenix reached over 100ºF.This is nine days more than Yuma and 51 days more than Tucson, Arizona. During that same summer, a new record of 32 consecutive days over 110ºF was recorded in Phoenix.The normal annual rainfall recorded at the Phoenix Sky Harbor Airport is 8.29in (211mm) with the wettest time in March, averaging 1.07in (or 27mm) (Schmidli 1996).

The climate of Phoenix is similar to many of the world’s most rapidly urbanizing regions. Areas of China, the Middle East, South America, and India will all face climatic and natural resource challenges similar to Phoenix as they rapidly urbanize. Figure

-4 below, taken from the recent UN’s Millennium Ecosystems Assessment Report, shows major urban centers located in dryland systems around the world (United Nations 2005).

Table 1-1 displays urban population and densities within different world ecosystems on each major continent.The Phoenix region is a dryland ecosystem.

Figure 1-4. Urban and dryland systems of the world. Source: UN Millennium Ecosystems Report, 2005

Table 1-1. Urban population and densities by major ecosystems and

continent (CIESIN et al. 2004)

Figure 1-6. The Phoenix region is located in the desert Southwest.The City of Phoenix is located in Maricopa County. However, the Phoenix metro area stretches into the counties of Yavapai and Pinal.

Phoenix, the capital of Arizona, has a population of over .5 million people, making it is the fifth-largest city in the US. The population has grown by 15% since 2000 when it was ranked as the 14th most populous city in the nation, and Phoenix now has a population density of 3,186 people

per square mile.The Phoenix metropolitan area includes 23 cities and towns and 3.3 million people.The 1970s to 1990s were times of rapid growth in population and developed land. While development has become denser since the 970s, the average density increase is relatively low at two households per acre, and most development is spread out, similar to the development patterns introduced in the 1950s. The US EPA selected Phoenix as one of five states to receive demographic data review from the period 1970 to 2000.This study explored the relationship between population growth, land development, and other indicators of both environmental health and quality of life (US EPA 2000).

Figure 1-7. Land-cover change from 1975-2000 in the Phoenix area, shows a clear increase in urban land cover and decrease in agricultural land (Data Source: Analytical Tools Interface for Landscape Assessments (ATILA) metric data).

Agriculture was the dominate land cover in the area up to the 1970s. Fields of cotton, citrus, and wheat were in close proximity to the city, and spread to the southeast along the natural water flows. Cattle and dairy farms were also a major source of income. As the population grew, much of this agricultural land was converted into residential subdivisions and commercial properties. Agricultural land conversion was most economical as this land was accessible by road and adequate supplies of water were already allocated to these properties. As the city expanded, it also grew to the north, where much of the land was state desert land and required full scale land development, placing more infrastructure costs on the developers.

Over the 30-year period of 1970-2000, the average urban population density in the Phoenix region slightly increased to 5.89 people per acre (2.59 = 1 average US household in 2000). A transportation research study suggested that this

population density is much lower than the 15 people per acre needed to support public transit (Ewing 1999). When only new development in the metropolitan areas is considered, the trend is much different. During each decade from 1970 through 2000, population density was 30% more dense in the new development areas than the areas developed during the preceding decade (Figure 1-8).This trend is likely to have continued since 2000 with new multifamily residential buildings in both infill locations and on the newly developed fringes.

Figure 1-8. Phoenix Population Density of New Development (Sources: Analytical Tools Interface for Landscape Assessments [ATILA] metric data and US Census).

The population of Maricopa County, which includes most of the Phoenix metropolitan areas, is expected to more than double over the next 50 years from its population of 3.7 million in 2006 to 7.9 million by 2055 (AZ Department of Economic Security).This continued growth will drive the construction for new living, working, and recreational facilities and has the potential of increasing the urban environmental problems that Phoenix already faces. Planning for this growth will require a new approach to development—one that is environmentally, economically, and socially sustainable.

Next, we will discuss the most common environmental problems found in the urban areas of developed nations. Particular attention is given to the problems that the Phoenix region faces as it continues to grow and mature

Urban Environmental Problems

Urbanization over the last century has resulted in many environmental problems, including atmospheric pollution, depletion and degradation of forests, deterioration of water resources, loss of countless species, and rapidly declining marine resources, all of which can be linked directly or indirectly to human activity.

Urban centers are situated within a variety of natural ecosystems.These concentrations of human activity affect and are affected by natural cycles. Urban areas import water, energy, and materials which are transformed into goods and services

Figure 1-9. The shifting environmental burdens as wealth of cities increase.

Source: McGranahan et al. 200

and then released back into the natural system in the form of air emissions, waste, and degraded energy. Degraded energy is defined here as energy that is released into the environment that no longer serves a useful purpose. Exhaust heat from combustion, noise from machinery, and solar thermal energy stored in urban construction materials are all examples

of degraded energy that affect the ambient environment. When urban centers exceed the natural capacity of the local ecosystem to assimilate and process these wastes they ultimately cause a shift or change in the local, regional, and even global environment.The environment within urban centers directly affects the health, productivity, comfort, and well being of its inhabitants. Urban environmental pressures can come from a variety of sources including air pollution, noise, traffic congestion, thermal climate change, and poor land use.These pressures will often increase as an area becomes more densely urbanized if the necessary infrastructure is not effectively planned and implemented to meet this growth.

Urban environmental problems can also have different consequences at different spatial scales. If we think of these three spatial scales as local, regional, and global, we can better define these problems and describe how they impact the environment around us. Historically, the burden of environmental problems is shifted as societies experience economic development

(Figure 1-9). Where poor settlements battle with sanitation that impact human health, wealthier cities are able to shift these environmental burdens away from the local level.The resulting shift, however, has a far greater impact on the systems at a global scale.

Table 1-2. Priority problems in urban systems and ecosystem services at three different spatial scales Source: UN 2005

The urban environmental problems can be grouped into three general categories:

1)  Over Consumption of Energy, Water and Material Resources

2)  Production ofWaste,Harmful Emissions and Degraded Energy

3)  Lack of Infrastructure to Ensure Health and Well Being of Inhabitants

The urban environmental problems outlined above characterize the most pertinent issues in both the developing and developed world. Each urban center also has its unique problems that relates to the geographical location, historical development patterns, and lifestyles of its inhabitants.

Development in the Phoenix region is unique in that it is…

• the fastest growing metropolitan area in the country
• centered in one of the driest and sunniest climates in the world
• has a finite water supply and a recent history of drought
• spread out, creating a dependency on personal automobiles for transport
• dependant on other regions for most of its food, water, materials, and energy
• has a pronounced urban heat island

These regional problems present both challenges and opportunities.The following sections discuss these regional sustainability issues in greater detail and their implications for future development in the Phoenix region.They are presented within the three major contexts that affect all urbanized centers.

Overconsumption of Resources

ENERGY

Urban quality of life and the environmental quality of modern cities directly correlates to energy.The development, operation, and renewal of urban centers dramatically impacts energy consumption. A World Bank study shows that a 1% increase in capita GNP leads to an almost equal increase in energy consumption (Santamouris 2000).This study also reported that energy consumption increased twice as fast as the rate of population growth in urban areas (2.2% per 1% in population change).

For developed nations, the greatest priorities for cities should be aimed at reducing overconsumption, increasing the use of renewable resources, and limiting the production of waste and degraded energy to a level that can be handled by the local and regional ecosystems that support the urban area.

Energy Production and Utilization

Understanding energy production and utilization is one of the most important components of sustainable development. Viewing energy from a historical perspective reveals how quickly energy production and utilization became a part of modern society and also offers insights into what to expect for global demand as other nations begin to follow the same energy- hungry patterns and dependence. First, the primary energy sources categories will be defined.This will give a background to the trends of the nation’s acquisition and use of energy over the last fifty years.

Primary energy can be grouped into three broad categories: fossil fuels, nuclear, and renewable energy. The largest energy source fossil fuels, constitutes 80% of the US energy fuel mix, includes coal, petroleum, and natural gas. The annual consumption of fossil fuel in the US in 1949 was 29 quadrillion British thermal units (Btu). In 2006 this consumption had reached 85 quadrillion Btu (EIA 2007).

Figure 1-10. United States energy flows from source to utilization in 2006 (Quadrillion Btu) Source: EIA, 2007

Nuclear power was used for the first time in 1957 and experienced rapid growth through the eighties, leveling off in the nineties and remained fairly constant since. In 2006, nuclear energy was responsible for 19% of all electrical production in the US and 8% of all energy (EIA 2007). While nuclear energy does not contribute to global warming, the spent cores are highly radioactive and there is no know permanent disposal method, presenting a unique and dangerous long-term environmental problem.

Renewable energy is naturally regenerative energy, as opposed to fossil fuels and nuclear power which are based on finite resources. Renewable energies typically have replenish cycles of several years or less (Figure 1-11). The major forms of renewable energy include: hydro; bio-energy – including biomass (wood and agricultural waste), biofuel (plant derived ethanol and biodiesel), or biogas (methane); geothermal; solar; and wind. Before the 19th century, wood was the primary fuel source with wind and hydro also in use. Renewable energy has recently gained attention once again as the world is more aware of the limited supplies and impacts of fossil fuel dependence. In 2006, renewable energy accounted for only 7% of US total energy consumption (EIA 2007), and 42% of this was hydroelectric power generation. Due to government policies and incentives, renewable energy is expected to be the fastest growing energy sectors in US in the following decades.

Figure 1-11. Energy sources and typical times to replenish

Source: Salt River Project, 2004

Historical Background

In 1950, energy production from petroleum outpaced the use of coal, and remains the single largest energy source, mainly in the transportation sector. In the 1960s the growth of automobile ownership caused the US’s petroleum consumption

to outpace its production, and the US began importing energy from other countries. Relations and import costs with these exporting countries are likely to be intensified as petroleum demands increase in the US and globally over the coming decades. The US dependence on foreign oil is an important matter of national security, leading politicians to consider alternative sources and energy conservation for more than just environmental reasons. Coal remains the largest energy source for electrical power generation, and the US produces all of its own electrical energy.

Figure 1-12. US Energy consumption by source from 1635 to 2006. EIA 2007

Energy use per person in the US was roughly 215 million Btu in 1949 (Figure 1-15). This increased until the late 70’s and has remained around 330 million Btu since.The leveling effect may be evidence of efficiency improvements from generation to the end use since the 1970s. Despite this leveling off, it is over 50% more than per capita consumption in 1949.

Figure 1-13. US petroleum consumption, production and imports since 1949. Source: EIA, 2007

Figure 1-14. Barrels of petroleum imported every day from various countries in 2006. Source: EIA, 2007

Another interesting trend is the amount of energy consumed, compared to the normalized value of one dollar’s worth of US output of goods and services. Since the 1970s there has been a decline in the energy required to produce one dollar worth of product (Figure 1-16).This could be the result of improvements in efficiency or the gradual change of the economy from manufacturing to services.

Figure 1-15. Energy consumption per person n the United States from 1950 to 2006. Source EIA, 2007

Figure 1-16. Energy use per real dollar of gross domestic product. EIA, 2007

Fossil fuels have dominated energy consumption in the US since the late eighteen hundreds while renewable energy (hydroelectric) has remained steady. In 1988, nuclear power exceeded renewable production (Figure 1-17).

Figure 1-17. Historical energy consumption and outlook for the US, 1949-2030. Source: EIA 2007

The future of energy consumption in America, assuming current laws, regulations, and policies, is not much different than what we see today. Projections show growth at a steady rate for all sources except for natural gas and nuclear energy, which remain constant (Figure 1-17). With the exception of any major discoveries or policy changes in the near term, our reliance on fossil fuels; petroleum, natural gas, and coal will most likely continue to intensify.

Renewable energy is one possible alternative to fossil fuels and imported petroleum. Government policies, technological efficiencies and current production methods continue to limit the expansion of renewable energy mainly because change to these technologies is not economically sustainable for utility companies. Hydroelectric power comprises most of the nation’s current renewable energy, but due to environment restrictions and limited water supplies, no new hydroelectric power plants are planned for the near future. Biofuels have seen a rapid increase over the last four years with new ethanol and biodiesel plants popping up all over the Midwest. Due to the competing needs for corn and other agriproduct sources, the increase demand for biofuels are expected to force corn prices to increase, also affecting the costs of meat production and other products. In addition to food supply concerns, corn production is enhanced with nitrogen-based fertilizers created using petroleum.The balance of energy and emissions associated with production and combustion are leading experts to discourage the future development of biofuels using conventional growing techniques.

Greenhouse Gas Emissions from Energy Generation

Carbon dioxide (CO2) is the most significant greenhouse gas in the atmosphere.The other greenhouse gases: methane nitrous oxide, hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) are just as dangerous but not being emitted at the rate of CO2. The carbon in fossil fuels combines with oxygen during combustion to form carbon dioxide. In 2005, carbon dioxide emissions in the US reached 6 billion metric tons, up nearly 20% over 1990 levels (Figure

-18). Combustion of fossil fuels in electrical power production and transportation are the primary sources of anthropogenic CO2 emissions that have led to global warming.

While the general industrial sector decreased carbon emissions from 1980 to 2005, the transportation, and residential and commercial sectors are continuing to rise (Figure 1-19).The residential and commercial carbon emissions are directly related to the electrical and natural gas energy used within buildings. The commercial building sector has seen a 60% growth rate

Figure 1-18. Greenhouse gas emissions, based on global warming potential. Source: EIA, 2007

Figure 1-19. Carbon dioxide emissions from energy use. Source: EIA, 2007

Figure 1-20. Gross domestic product versus energy related carbon dioxide emissions Source: EIA, 2007

since 1980s in CO2 related emissions. Slowing this trend requires new energy cognizant approaches to the way buildings are designed and operated.

The installation of efficiency improvements and emissions controls on power plants has created a recognizable decrease in the CO2 emissions.The decoupling of GDP and energy related consumption since 1990 suggests that economic growth is possible without the increase of energy consumption. All this leads to the conclusion that energy production, and energy use must be more tightly regulated and controlled to reduce US carbon dioxide emissions.

Methane emissions were 9% of total greenhouse gas emissions in 2005. Energy, waste management, and agricultural activity account for nearly all methane emissions in the US. 60% of energy related methane releases is during the production processing and distribution of natural gas (EIA 2007).

Energy Use and Vulnerability in Arizona and the Phoenix Region

Arizona boasts the most solar potential in the US and yet energy production in the state is almost entirely based on fossil fuels. The state has a substantial amount of natural coal deposits, concentrated in the northeast Navajo area of the state in an area called Black Mesa Basin, but few other fossil fuel resources.

Figure 1-21. Arizona energy sources, power plants and electricity transmission locations. EIA 2007.

Large volumes of coal are transported within and out of the state on railways, with one third of the coal mined in Arizona delivered to Nevada while the other two thirds are burned at generators around the state.The remainder of energy used in Arizona is from natural gas, nuclear and hydroelectric power.

Several major natural gas pipelines originating in Texas and the Rocky Mountains supply Arizona markets as they flow towards southern California. Three fourths of this natural gas is used for electrical generators, and the remainder for residential and industrial heating.

Nuclear power comes from the state’s sole nuclear plant, Palo Verde. The plant, located 60 miles outside of Phoenix provides about a quarter of the state’s electrical power and is the nation’s largest nuclear plant. Glen Canyon

Dam and the Hoover Dam both sit on the Colorado River in northern Arizona and produce the state’s largest renewable energy supply.

Arizona has the greatest potential for using solar power in the country but because of the ample supply of coal and nuclear power in the area, solar generation facilities are few. Even passive solar technologies such as solar hot water collectors are in limited use, making plant generated electricity the primary energy source for both heating and cooling buildings.

Figure 1-22. Energy sources n Arizona from 1960 to 2004 Negative consumption values on

the graph indicate exported energy outside of Arizona. Source: EIA, 2007

Figure 1-23. Energy consumption per person by US State. Arizona is among the lowest per capita energy consumption in the US in 2006. Source: EIA, 2007

When compared to other states’ per capita (per person) energy consumption, Arizona is the fifth lowest in the United States. However, the graph in Fig. 1-23 may be misleading as an indicator of how much energy the average person uses, as it expresses gross usage in the state. In states with heavy manufacturing and/or mining industries such averaging will show considerably higher per capita consumption than states having high populations or service oriented economies. In comparison with other states, Arizona does not have an energy intensive economy.

The majority of energy used by the average Arizona consumer is in the form of electricity. In 1999, the total electrical energy consumed in Arizona amounted to 58,143,730 MWh.This electrical demand was met by a diverse fuel mix comprised of 46% coal, 36% nuclear, 12% hydro electric, and 6% gas (DOE 1999). Arizona’s electrical generation was nearly twice that consumed at 107,965,747 MWh. Much of this excess energy is lost in energy distribution, called line losses, or it is distributed and sold to other states, predominately Nevada and California. As of 2000, there were 22 generation plants in Arizona operated by eight companies.

Table 1-3. Arizona generation by operation, 2000. (Source: U.S. DOE, 2000)

Figure 1-24. Industry generating capability in Arizona by primary energy source, 1999.

Source: U.S. DOE, 1999

The generating mix capacity in Arizona as reported by the Department of Energy (DOE) shows a potential balance between fossil fuels, nuclear, and hydroelectric as shown in Figure 1-24. Actual generation in Arizona, however, is much more heavily dependent on coal and nuclear, as these two energy sources offer the most inexpensive and readily available energy in Arizona. (Figure 1-25)

Figure 1-25. Actual industry electrical generation by energy source in Arizona, 1999. Source: U.S. DOE, 1999

Arizona does not currently have a petroleum refinery and relies on two pipelines to supply petroleum products such as gasoline, diesel and aviation fuels One pipeline originates in Southern California and one from El Paso,Texas. The lines are vulnerable to disruption and can have major implications on the gasoline supply in the Phoenix region. In the summer of 2003, a rupture

n the line from El Paso shut down the line between Tucson and Phoenix for several days, causing a fuel shortage in the Phoenix area. To alleviate the pressure on petroleum supplies, a new refinery in Yuma, Arizona is proposed to be operational by 2010.The refinery would receive crude oil piped in from Mexico to produce an oxygenated motor gasoline blend which is used year round in the Maricopa County to limit automobile impact on air quality.

The electric power industry in Arizona ranked 18th highest in carbon dioxide (CO2) emissions in 2004 and continues to rise as energy production increases, and coal remains the dominant energy source. Other combustion related pollutants include sulfur dioxide (SO2), and nitrogen oxides (NO ). Due to new air emissions control regulations both SO2 and NO have been on a downward trend since 1989 (Figure 1-26).

Renewable Energy Policy and Incentives

Solar Energy in Arizona

Global spending on solar is expected to increase from

$2.3 billion in 2006 to more than $16 billion in 2010. In Arizona, utility incentives to help buy down the cost of solar energy systems has increased from $500,000 in 2003 to more than $12 million in 2006. Combined with local and federal incentives, solar funding for Arizona ratepayers could reach $30 million by 2010 (Arwood 2006).

The Federal Energy Policy Act of 2005 (EPACT 2005) allows homeowners a federal tax credit of 30% for qualifying solar electric (PV) or solar water- heating expenditures, up to a maximum of $2,000 per

technology. For businesses, the incentives have also been increased from 10% to 30% with no cap limit. EPACT

Figure 1-26. Arizona airborne emissions, electricity sector, 989-2004, metric tons. Source: EIA-767 and EIA-906 Survey, Energy Information Administration.

2005 only allotted for two years of incentives, but companion bills are likely to continue the incentives through 2015 (Arwood 2006).

The Western Governor’s Association (WGA) chaired by Arizona Governor Janet Napolitano met on June 11, 2006 to adopt a broad based set of proposals for meeting future energy needs of the region. They released a report entitled “Clean Energy, a Strong Economy and a Healthy Environment”.The goals set in the report are to develop 30,000 megawatts of clean power by 2015, increase energy efficiency by 20%, and ensure secure, reliable transmission for the next 25 years (WGA 2006).The report made sixteen different recommendations to increase and extend the production tax credit for renewable- energy technology for 10 years and to raise the cap on residential investment tax-credit to $10,000 for renewable energy or distributed-generation systems.

The Arizona Corporation Commission (ACC) became a leader in renewable energy regulation when it required that Arizona utilities have at least 1.1% of their generation mix from renewable sources. In 2006 the ACC increased that commitment to 15% by 2025.

One provision in the Commission’s new Renewable Energy Standard is a 30% set-aside for distributed energy sources.This includes rebates to customers that generate their own electricity on site from renewable energy, and expands the eligible equipment to more then just solar PV and water heating.

With so many incentives and government requirements, solar energy should be booming in Arizona and around the United States. The demand for photovoltaic solar energy systems is unfortunately outpacing production, leading to higher costs globally. The main source of this lag is the production of polysilicon, the base material and most critical component of photovoltaic technology. According to Michael Rogol of Credit Lyonnais Securities Asia (CLSA) in a recently published report on the shortage of polysilicon, as recently as five years ago the solar industry silicon demand was quite small. Since 2001

the market has skyrocketed, resulting in 48% of the global silicon production going towards solar and the other 52% to the electronics industry. Another 40% growth in the solar industry was experienced in 2006 but the silicon supply only grew from 36,000 tons to 38,000 tons between 2005 to 2006. Rogol predicted that the production is not expected to catch up to demand until 2010, when the production of raw silicon is expected to double current production to nearly 85,000 tons a year. In 2005, silicon solar cell production equated to 1.7 gigawatts (GW) globally and by 2010 that number is expected to reach 0 GW (Arwood 2006). One gigawatt is roughly equivalent to the average electrical power needed to supply 300,000 US homes. This growth of nearly 17%, far exceeds the 5% growth projected for the electronics industry. Because more than 30% of the raw material costs for solar cells are spent on silicon, the shortage will have a much greater impact on the solar industry than on the electronics sector, where only 1% of the costs are for silicon.

Over 90% of current solar cell production is silicon-based.The gap in silicon production will open doors for the under- represented emerging solar technologies that utilizes less or no silicon. Two technologies that will benefit are thin film photovoltaic products and concentrating solar power.

Thin film technologies use a coating that can generate electric power without the use of silicon. It is also possible to apply this film to almost any surface. The increased demand for thin film would be good for two Arizona based solar companies First Solar of Scottsdale and Global Solar in Tucson.

Polysilicon shortages may also shift public attention to Solar Concentrating Power (CSP) technologies. When utilized in large scale production, solar concentrating power offers the most cost effective energy production, in comparison to other solar power systems. CSPs come in many shapes and sizes: parabolic troughs, dish, and solar towers. One of the most successful companies in the industry, Stirling Energy Systems (SES), is based in Phoenix. SES manufactures a Stirling Dish System that converts thermal energy into electricity using a highly efficient Stirling engine generator at the apex of a mirror array.The company is currently building a plant in California that will supply 1,700 megawatts to Southern California. Unlike PVs, CSP systems rely on direct and not diffuse radiation.Therefore, CSPs are most appropriate for areas with consistent clear skies and sun. Arizona will likely see a great increase in CSP systems to meet the renewable energy portfolio by 2015.

WATER

The City of Phoenix lies at the nexus of the Salt and Gila rivers in the Sonoran Desert. For nearly 2,000 years, the native Hohokam culture inhabited this land, creating .a sophisticated system of canals to channel the water from these rivers to crops, and traces of these canals were still in evidence when modern settlers arrived in the area. Canals and water have remained the lifeblood of the region. Aggressive modern water projects brought agriculture to the region, leading to a steady increase in population. After the invention of air-conditioning, there was a rapid increase in development of the region. With population increase, the demand for water increased.Throughout the 1960’s, most of the area’s water came from groundwater sources.

The overdependence on groundwater led to an unsustainable condition that ultimately caused the gradual sinking of some areas over the aquifer.The Central Arizona Project (CAP), completed in the late 1980s, is an aqueduct system that brings water from the Colorado River. The CAP was paid for and used mostly by farmers in its earliest function, but as the urban areas began to rapidly grow, CAP water was used to meet the demand from urbanized areas.The CAP and other surface water projects, such as the many reservoirs constructed in the region, have all but eliminated the dependence of groundwater in the area. Private land owners, however, continue to draw groundwater on their property despite the long-term implications Recent drought has induced a growing concern about water scarcity in the region. On the positive side, a large percentage of new development has replaced what once was agrarian land where agriculture practices used a much larger amount of water per acre compared to residential and commercial buildings, and this water savings is expected to enable the expansion of the urban area for several years before water becomes a pressing economic issue. At present, the cost of water is so low that most governmental conservation efforts go unheeded. Water conservation, however, will be crucial to meeting the future demand of Phoenix’s growing population. Local governments and utilities are beginning to promote water-conservation campaigns and integrate conservation policies such as landscaping ordinances and plumbing codes into future development requirements.

Arizona’sWater Supply

Arizona uses roughly 8.1 million acre-feet of water every year. One acre-foot equates to 225,851 gallons, equal to the annual consumption of a five-person household. Arizona’s water supply is comprised of four basic sources: Colorado River water (34.5%), surface waters other than Colorado River water (17.2%), groundwater (35.8%) and effluent reclaimed water

(12.3%)(ADWR 2002). The rate at which any give water source is used depends upon its relative quantity, quality, reliability, and economic feasibility.

Figure 1-27. Arizona’s average annual precipitation.

SurfaceWater

Surface water from Arizona’s lakes, rivers, and streams is a renewable resource. In spring, snowmelts replenish the surface-water supplies, if inconsistently. Because a large percentage of the state is desert, the amount of water varies from year to year, season to season, and place to place.To decrease the fluctuations in the water supply and to increase reliability, a highly developed system of storage reservoirs and delivery methods have been constructed throughout the

state (ADWR 2002).The largest and most important reservoirs are located on the Salt,Verde, Gila. and Aqua ria rivers

Colorado River Water

Colorado River water is categorized separately from the other surface water rivers of Arizona because it is has important legal and political implications for the Southwest and the Phoenix region.The federal government constructed a number of reservoirs to use Colorado River water in several states including Arizona, California, Nevada, New Mexico, Utah, Colorado, Wyoming, and Mexico. Several legal authorities quantify the rights to the Colorado River.This legal arrangement, referred to simply as the “Law of the River,” mandates that 2.8 million acre feet each year be allocated to Arizona. Mohave, La Paz, and Yuma counties depend almost entirely on the Colorado River supply.The remaining 1.6 million-acre feet is then delivered to Maricopa, Pinal, and Pima counties via the Central Arizona Project (CAP) canal.

Table 1-4. Arizona water supply and annual water budget for 2006. (ADWR 2006)

Groundwater

Groundwater constitutes 36% of the state’s water.This natural water source is found beneath the ground in natural reservoirs called aquifers.This water, often millions of years old, has been pumped out at a steady rate over the last century. When groundwater is pumped out faster than it is replenished, the condition is called overdraft. Location relative to end use, depth below the surface, and water quality limit the availability of groundwater.The long-term water sustainability of the region depends on our ability to manage and prevent overdraft of Arizona’s aquifers. In 1980, Arizona implemented the Groundwater Management Code to promote the conservation and long-range planning of water resources

ReclaimedWater

Reclaimed water, or effluent, is water that has been treated at a wastewater treatment plant for reuse, and constitutes 2% of Arizona’s water supply. Reclaimed water is treated to a high quality, in some applications higher than drinking water

requirements. For this reason, reclaimed water is a safe and economic resource for purposes such as agriculture, golf courses, parks, industrial cooling, or maintenance of wildlife areas. Reclaimed water can be considered a growing water resource in Arizona, as the more the population grows and water use and disposal increases, the more reclaimed water can be available Lack of piping infrastructure to end use points remains a problem.

Future Challenges and Opportunities

The Arizona Department of Water Resources (ADWR) suggests that Arizona’s water supply faces both short- and long- term challenges.

RuralWaterSupply

Water supply conditions in rural Arizona communities comprise the most severe water problems in the state. Rural areas continue to grow in population as new communities develop without adequate water supply or financial resources.The demand on groundwater is excessively high, and the withdrawal of water continues to impact the natural water flows that support riparian and recreational areas.The water-supply challenges of these rural communities will only increase as drought conditions persist.

Colorado River Operational Planning Framework

As populations continue to grow and drought conditions persist in the Colorado River Basin states, managing the Colorado River grows increasingly complex.The key issues of the 21st century will require the establishment of agreed-upon criteria

for decision making in drought conditions, new management methods, and coordination between the seven states of the Colorado River Basin

Long-Term Challenges and Opportunities

To effectively manage and set goals for Arizona’s vital groundwater supply, ADWR has designated groundwater basin areas based on the physiography, surface- drainage patterns, subsurface geology, and aquifer characteristics. Of the basins, four were designated Active Management Areas Phoenix AMA,Tucson AMA, Prescott AMA, and Pinal AMA

There is concern about the ability of these AMAs to achieve and maintain their long-term management goals. Even though a substantial amount of progress has been made through the use of surface water, conservation programs, and conversion of water rights, most of ADWR’s projections are indicating shortfalls in the future.The Phoenix AMA, for example, has been continually reducing its groundwater overdraft quantities, but even in 2025, Phoenix may still exceed its groundwater withdrawal goals.The Tucson AMA will also make great reduction in groundwater overdraft, but ADWR projections show that area becoming steadily more dependant on the CAP water flows.The Prescott AMA is using and committing future surface water supplies to new subdivisions, which may result in doubling the long-term sustainable supply of groundwater.

The AMAs are a very important part of Arizona water-supply management and achieving the statutory goals of the AMA will help to ensure adequate, dependable water supplies for Arizona communities in to the future.The success of the AMA management goals will depend on both regulatory and nonregulatory programs and policies, cooperation between regional entities, and technically advanced long-term planning.

Energy = Water

Energy and water, two of the most important components of modern civilization, are interdependent in several ways, and

are often used to indicate the economic and environmental sustainability of urban areas. Water supply extraction, delivery, and processing of water can be energy intensive, and this is particularly true in areas such as Phoenix which rely heavily on water supplies that are not readily accessible. Wells, canals, and water-treatment plants use pumps, valves, and gates that consume electrical energy to manipulate water from source to use and then back to the ecosphere.

Water has been used for centuries to generate mechanical and electrical power, up to the Mega Watt hydroelectric dams of present-day Arizona. Today, nearly 12% of Arizona’s energy comes from hydroelectric power plants. (DOE 1999) The remaining 88% of Arizona’s energy generation each year is from thermoelectric power plants fueled by either coal or nuclear power.Thermo¬electric power plants generally burn a fuel to

Table 1-5. Water withdrawals by use in the US in 2000 (Golden 2006).

transform water into steam that is then sent through a turbine generator to produce electrical power. Water is used directly as the working fluid, and it is also used to cool the steam to complete the power cycle. In the US, thermoelectric power generation withdraws more water than any other water usage, including agricultural irrigation and municipal consumption (Table 1-5).

In 1985, freshwater withdrawals in the US averaged 338 billion gallons a day (Bgal/d). By 2000, this number had increased 21% to 408 billion gallons a day. Most of this increased use was from groundwater sources, an increase in groundwater withdrawal of 14% to 83.3 Bgal/d. Approximately 195 Bgal/d, or 48%, of all freshwater and saline water withdrawals were used for thermoelectric power (Golden 2006), with 56 billion gal/day of saline (ocean) water for electrical generation cooling in coastal areas. For every 100 gallons withdrawn from surface water for cooling in these power plants, 98 gallons is treated and returned to the source body while 2 gallons are lost to evaporation.The total consumptive loss for once-through cooling systems is nearly 18ft2/s (0.5m3/s) per 1000 MW, and 30ft3/s (0.9m3/s) per 1000MW for cooling towers (Golden 2006).

The National Energy Technology Laboratory (NETL), operated by the DOE, estimated that 25 gallons of water is required to produce 1 kWh of electricity from a coal plant (Feely et al. 2005). Another study showed that 1 kWh of electricity requires 37 gallons of water for fossil-fueled plants and 56 gallons for nuclear-powered plants (Scharff 2002).

An ASU research study estimated the total water withdrawal and consumption for energy use for an average family in Arizona. Results showed that the annual energy use in an average house in Phoenix equates to 8,420 gallons of water and, of that, 6,530 gallons is lost to evaporation during the thermoelectric generation process (Golden 2006).This connection between water and energy use is a growing concern for cities experiencing water availability problems. Power-plant water consumption may conflict with either existing or potential downstream municipal water use or with in-stream water uses. As populations and energy demands grow, so will the need for water for thermoelectric power plants. One option for municipalities and power utilities is to require that cooling towers use reclaimed water for thermoelectric generation. Palo Verde Nuclear Generating Station, operated by Arizona Public Service, produces over 1,200 MW of power using reclaimed water from nearby Phoenix in their two reactor cooling loops.Though Palo Verde sits in one of the driest places in the US, it has an enormous cooling pond and canals to manage its water needs.

Some renewable- energy technologies such as wind turbines and photovoltaic panels operate using little or no water.This additional benefit of renewable energy should be taken into consideration in areas with limited water resources

Figure 1-28. Steam cloud generated from cooling towers at APS’s Ocotillo thermoelectric power plant in Tempe, AZ (Source: City of Tempe).

RESOURCE USE

Every human requires a certain amount of natural resources to support them throughout their lives.These natural resources are the foundation for the products we use, the food we eat, the water we drink, the energy we use to light and heat our homes, and in the ecosystem that degrades our wastes.

This portion of world resources is often referred to as a person’s ‘ecological footprint’ and is defined as follows:

Ecological Footprint – “The area of land and water required to produce the resources consumed and to assimilate the wastes generated by a population on a continuous basis, wherever on earth that land is located” (Wackernagel and Rees 1996).

The ecological footprint can be calculated for a single person, a family, a building, a city or an entire country. Given the current world population, there are only about 1.5 hectares of ecologically productive land and only about 0.5 hectares of productive ocean per person on earth (Wackernagel and Rees 1996). Calculations of various countries per capita ecological footprint reveals a great divide between the footprints of wealthy countries and less- developed ones. High-income countries generally have ecological footprints of 5 to 6 hectares while the top wealthiest exceed 10 hectares per capita. In addition,

in some underdeveloped countries, the average person can often have ecological footprints of much less than 1 hectare (Wackernagel et al. 1997).

Figure 1-29. Material budget (tons per year) for an individual human from Neolithic to modern times. Lifetime storage refers to the materials that are in the form of buildings and products (Decker et al. 2000).

The ecological footprint of a city is a function of the combined footprints of its average citizen multiplied across the entire population. For London, England the estimated area of land required to assimilate its CO2 emissions, provide food and forest products is 120 times that total land area of the city (Sustainable London Trust 1996). Other cities such as Toronto, Canada with a population of 2.38 million requires a land area 288 times its size, and Vancouver, Canada’s ecological footprint requires 319 times its land area

It is important to note that, if the entire world was brought up to the resource consumption standards of the average American, we would require the equivalent ecological capacity of six earths.

Waste, Emissions and Degraded Energy

SOLID WASTE

The US EPA categorizes solid waste as either municipal solid waste or non-municipal solid waste. Municipal solid waste (MSW) is defined as wastes such as durable goods, nondurable goods, containers and packaging, food scraps, yard trimmings, and miscellaneous inorganic wastes from residential, commercial, institutional, and industrial solid waste sources.This form of solid waste is under the control of occupants in the home, business, or office and therefore draws the most public attention and concern. Most reported recycling rates for a metropolitan area is based on materials recycled from MSW, however

the total waste stream produced in the US also includes non-municipal solid wastes (NMSW) from heavy industrial and commercial sources. NMSW can range from construction and demolition debris, automobile bodies, municipal sludge, combustion ash, and other industrial processes.These wastes are a significant part of the total US waste stream. ‘Diversion rates’ are based on both forms of solid waste streams, and signifies all waste recycled, reused, or otherwise reworked and kept from disposal areas.

In 2000, the US EPA released a report entitled Municipal Waste Generation, Recycling and Disposal in the US: Facts and Figures.This study characterizes the municipal solid waste stream for the Year 2000. The total solid waste generated in 2000 was 231.9 million tons, an increase of nearly 1 million tons from the previous year, while the total per person waste generation decreased during the same period.This indicates that US has increased its rate of recycling as population has grown.The breakdown of the US waste stream as reported for 2000 is shown in Figure 1-24 .

Figure 1-30. Municipal solid waste stream for the US in 2000. a total of 231,900,000 tons (EPA 2000).

Recycling in Arizona

In 1990, the Arizona State Legislature passed the Recycling Act and since then Arizona

has increased the amount of waste recycled or diverted from landfills. Progress has been hindered, however, due to factors unique to Arizona. Compared to other states, Arizona

has low landfill disposal fees and available open and for future landfills.These factors result in recycling costs that are greater than the cost to dispose the materials for many areas of the state.This economic disincentive had resulted

in limited recycling increases in areas located far from recycling markets. Recycling programs have had some success in urban areas where local municipalities target their residents and encourage them to recycle. In 2002, the three Arizona jurisdictions saving the most landfill space by recycling were the City of Phoenix, Maricopa County, and the City of Mesa The City of Phoenix offers a comprehensive set of recycling and waste-reduction programs with curbside recycling for single-family homes and three drop-off locations for recyclables within the City limits.Two material-recovery facilities (MRFs) are responsible for processing all of the City’s municipal solid waste, one located on 27th Avenue and the other at Hudson Baler. Household hazardous waste (HHW) and battery, oil, paint, and antifreeze collection events are also offered regularly.The City’s landfills can also accept clean loads of “green” waste that are chipped and then reused as landscaping mulch.The City was able to divert an additional 504,000 cubic yards (173,000 tons) over any other Arizona jurisdiction in 2002.The total solid waste generated and diverted for a variety of jurisdiction is given in Table 1 6. In terms of total diversion rate, Phoenix was the fourth highest (12%) in the region, behind Scottsdale (13%), Chandler (14%) and the extraordinary rate of Wickenburg (95%). The more telling indicator is the waste generated and diverted per person.Table 1 6 indicates that the average person in the region generates 2,125 lbs of solid waste a year and recycles about 190 lbs per year (9%).The citizens of Kearny, Arizona can boast that they generated nearly 500 lbs less than the average (1,689lb total per person), and the citizens of Surprise are reported as having the highest generation of 2,490 lbs per person. Due to the variety and level of recycling programs and citizen involvement, there is a wide range in the rate of waste diverted.

Table 1-6. Solid waste generated and diverted by local government jurisdictions (ADEQ 2002)

Residential Curbside Recycling

Residential curbside recycling is the most convenient and effect method for citizens to recycle. A residential curbside recycling program is defined by the ADEQ as “any program that collects a variety of materials left in close proximity to their sources on a regularly scheduled basis.”The program requires the collection of at least one recyclable material beyond green waste. In most instances, a recycling bin is supplied to each household, and recycling is picked up once a week, where solid waste pick-up is twice a week. Curbside recycling significantly promotes recycling and creates a habit for households

where the program is offered. In most cases in the Phoenix region where recycling rates are low, curbside recycling is not the implemented method used.

The method of collection and required sorting of collected materials can vary between programs.The recyclable materials may be source separated by the recycling program participant, sorted at the curb, or commingled where the jurisdiction sorts the ‘total’ residential waste stream.Total sorting facilities are often referred to as “dirty material recovery facilities.”

Curbside recycling programs can be carried out and operated by municipal solid waste management departments, large hauling companies, or small businesses.The City of Phoenix operates the largest recycling program in the state of Arizona, while Jerome has the smallest.There are nearly 974,000 homes that are currently being served by a curbside recycling program in Arizona, representing 48% of the total population (2,570,000). Arizona’s history of curbside recycling dates to 1988 when the City of Tempe began the first trial program of 816 homes. In 1992, Gilbert was the first city to offer the service to all single-family homes. Curbside recycling around the county has shown growth as metropolitan areas began introducing programs across jurisdictions.

Figure 1-31. Curbside recycling from 1988 to 2002 in Arizona by number of households and number of jurisdictions. Several curbside programs were discontinued because of lack of funding from 1995 to 1998 (Source: ADEQ 2002).

Figure 1-32. Diverted municipal solid waste (by tons) for the City of Phoenix in 2002.Total diverted = 172,572 tons (12.1%) (Source: ADEQ 2002).

Table 1-7. Category descriptions of diverted municipal solid waste in Arizona.

Recycling Programs Costs and Revenues

Recycling programs are not free, but if organized correctly, can create a revenue opportunity for the jurisdiction that implements them.The cost of operating and maintaining a recycling program includes:, land needed for holding and sorting, insurance, equipment, personnel, consultants, construction, any mandated procurement programs (purchasing recycled-content materials), and other related costs.The costs reported by Arizona jurisdictions in 2002 was as low as $1,200 per year for the City of Page to as high $9.9 million for the City of Glendale.

Revenues can be generated by recycling programs, mostly from the resale of usable items or the sale of a recyclable waste stream. In 2002, the City of Mesa reported a recycling revenue of $11,376,182, or nearly $7 million more than what was spent on the program The total statewide recycling revenue generated by all jurisdictions was over $18 million. Avoided costs from diverting waste from a landfill or incinerator should also be considered when calculating the total economic benefit of recycling programs.These savings can be estimated based on the tipping or disposal fees that would have otherwise been charged by the waste-collection company.

Symbols and Public Awareness

An important part of any recycling program is public education and awareness.These campaigns help to educate the consumer on which items can be recycled in their community.The standard recycling symbol, three chasing arrows, indicates that the product is recyclable (Figure 1-33). When the recycle symbol is set on a black background it indicates that the product used recycled material during its manufacture (Figure 1-34).The “recycled content” symbol will also include the percentage of the product made of recycled content.These symbols help consumers to quickly choose recycled and recyclable products.

Figure 1-33. The symbol indicating a recyclable product.

Figure 1-34. The symbol that the product is made of recycled content.

Figure 1-35. The logo for the Arizona Recycling Program.

The Arizona Recycling Program travels to schools, conferences, and other civic gatherings to promote the concepts of reduce, reuse, recycle, and buying recycled material products.The Arizona Recycling Program also has a symbol for their program on literature, education campaigns, and fundraising events.

SolidWaste and Energy

Using recycled materials reduces the amount of waste landfilled but it also reduces the energy needed to produce a product from new materials. Buying products with recycled content creates a demand for waste materials collected in recycling programs and stimulates markets producing these products. Over 37 % of the waste stream in the US is paper, and most paper products have recycled content. Abitibi Consolidated, Inc. located in Snowflake, Arizona uses old newspapers to produce new newsprint.This closed loop type arrangement significantly reduces energy, prevents pollution and slow the depletion of natural resources (ADEQ 2002).

Composting and Energy

Yard trimmings and kitchen scraps represent 23% of the MSW stream in the US. Organic materials such as these can be composted relatively easily at home or local collection facilities.

Composting is a process that involves mixing together yard waste such as grass, leaves, and landscape trimmings, along with selected food scraps to promote decay, resulting in compost.

Compost is the natural decomposition of plant material and other once-living materials.The finished product of a composting system is a dark, earthy substance that can be used to enrich garden soil. Backyard composting is an excellent way for residents of Arizona to reduce their total waste stream, and while reducing the energy required for transporting, processing and disposing of this waste material.There are several backyard composting programs located in Arizona to assist home gardeners in developing their backyard composting systems.

WATER QUALITY

Water quality and quantity are essential to the long term sustainability of Arizona and the Phoenix Region. Water quality is defined by its physical, chemical, biological, and aesthetic (visible appearance and odor) characteristics. Public and ecosystem health is greatly influenced by the quality of water in these systems. For this reason, the US EPA ranks water quality as one of

the highest-priority environment issues.

Groundwater is a major component of the public water supply and is vital to the health of the river and wetland systems in Arizona, and its availability and its quality has influenced the development of agriculture and cities in Arizona. As agricultural land

is converted urban use, groundwater sources are in closer proximity to industrial development and risk contamination and depletion.

To aid and encourage the management and viability of these groundwater supplies, the Arizona Department of Environmental Quality (ADEQ) adopted the groundwater basin boundaries delineated by ADWR’s Groundwater Management Act as ‘active management areas’ (AMAs): Phoenix AMA,Tucson AMA, Prescott AMA, Pinal AMA, and Santa Cruz AMA.These basins were chosen because they lie under the largest population centers and comprise the majority of groundwater supplies in the state. Figure 1-36 highlights each of these Arizona AMAs

Chapter 2 of Arizona State Environmental Quality Act,Title 49, adopted in 1986 deals with water

Figure 1-36.Arizona’s Active Management Areas (AMA) and Indian Nation Areas (INA).

quality in both surface and groundwater sources.The law helps to manage and protect water quality and remediate point and nonpoint sources of pollution.The statute aims to “protect water quality for all present and reasonably foreseeable future uses.”Title 49 established the Aquifer Protection Permit (APP) Program, industrial best available demonstrated control technology (BADCT), best management practices (BMP), and the Water Quality Assurance Revolving Fund (WQARF), all important groundwater protection and cleanup programs in Arizona.These programs have led to the near elimination of prohibited discharges to groundwater. Most contamination sites are the result of historic discharges that occurred before the ntroduction of Title 49 in 1986.

Groundwater quality can be affected by many different sources.The most significant contributing sources in Arizona include agricultural activities, wastes from industries, leaking underground storage tanks, septic tanks, landfills, mining and wastewater treatment plants.These sources leak volatile organic compounds (industrial solvents), nitrate, sulfate, metals, pesticides,

Volatile Organic Compounds

Solvent disposal is the leading cause of Volatile Organic Compounds (VOC) contaminated groundwater in Arizona. Aerospace and electronic companies are historically located in areas where these compounds have been found. Many manufacturing facilities use solvents for degreasing and their careless disposal has been documented since the 1950s. Historic industrial procedures included pouring these solvents into dry wells, releasing into surface impoundments, leach fields, and dry washes (Graf 1986). Dry- cleaning establishments were also notorious for disposing and leaking volatile organic compounds on site. Many wells in Phoenix,Tucson, and Payson have been closed due to VOC contamination.

Nitrates

The second most prevalent pollutant in the state’s groundwater is   itrate Both human activities and natural sources influence nitrate levels. Most human-related sources are from the percolation of water runoff from irrigation, septic tanks, wastewater treatment plants, and feedlots. Nitrate is unaffected by soil filtration and therefore concentrations remain the same as it moves with the groundwater.

Glendale, Mesa, Chandler, and Phoenix sit on the Salt River Valley aquifer with nitrate concentrations so high that it is not suitable for direct consumption. In more rural areas of the state, septic tanks may be the primary source of nitrate contamination making many wells unsuitable for drinking.

Major Cations and Anions (Dissolved Mineral Content)

An important water quality indicator is total dissolved solids (TDS) This indicates the relative level of dissolved mineral content and can vary widely in aquifers. High level so TDS render water unsuitable for drinking.

Metals

Some heavy metals occur naturally in groundwater. Arsenic is a naturally occurring heavy metal in Arizona.The federal and state maximum arsenic level was 0.05 milligrams per liter and that limit was lowered to 0.01 milligrams per liter by the US EPA in 2006. Much of Arizona’s water exceeds this level, making municipalities across the state implement treatment, blending, or use of alternative water supplies. Human-related metal contaminations can be chromium from metal plating and electronics manufacturing, as found in Phoenix and Tucson areas. Manganese, copper, iron, and chromium, are a result of mining operations and tailing ponds. Landfills can also be a source of metals such as iron, manganese, and barium.

Pesticides

Two pesticides were repeatedly discovered in groundwater before 1980 in Arizona. Now banned because of their potential carcinogenicity, dibromochloropropane and ethylene dibromide were commonly used starting in the 1950s in Yuma and the Salt River Valley to prevent nematodes in soils of citrus and cotton fields. Currently, pesticides atrazine, methomyl, metribuzin, and prometryn have been found in areas of Maricopa and Yuma counties at levels far below regulated limits.

Petroleum Hydrocarbons

Leaking underground storage tanks (LUSTS) usually contain petroleum-based fuels and are a major source of groundwater contamination in urban areas. As of 2002, there were 27,641 underground storage tanks containing regulated substances in Arizona. Of these, nearly 7,945 have been reported to be leaking. According to the ADEQ 5,523 of these leaking tanks have been remediated, disposed of, or properly closed. It is estimated that 19% of all LUSTs have resulted in adverse effects to groundwater quality. LUSTs are mostly associated with service locations such as utility, transportation, and shipping companies municipal facilities, pipelines and mining, food, lodging, high tech, and paint companies.

The chemicals most often detected LUST-related chemicals are

• benzene
• toluene
• ethylbenzene
• xylene
• total petroleum hydrocarbons (TPH)
• methyl tertiary-butyl ether (MTBE)
• 1,2-dichloroethylene (1,2-DCE)

Radionuclides

Uranium, radon, and radium are radioactive elements that occur naturally in soil and water throughout Arizona. Sources of groundwater contamination by radionuclides results from uranium mining. ADEQ and ASU have found radon concentrations of 300 picocuries per liter are considered naturally occurring.This level does not exceed exposure limits but is an interesting and unique characteristic of groundwater here.

Bacteria

Over 17 % of the state population uses septic systems to treat human waste.There are about 400,000 septic tank systems in operation. Groundwater contamination by bacteria can be linked to poorly designed septic systems and bad water supply well placement. Microorganisms in septic waste, which should be removed by passing through a few feet of soil, but in same locales are insufficient if the soil depth is too shallow or the soil itself is lacking the proper natural microbial life. Poor construction of water wells, or proximity of water supply wells to effluent flows is a common reason for microbial contamination in groundwater.

The Phoenix and Tucson metropolitan areas host most of the groundwater quality problems, however all 10 of Arizona’s watersheds have been contaminated at different levels of severity. Despite the efforts of the ADEQ’s Groundwater Quality Act and ADWRs groundwater protection programs, there are still many groundwater quality problems in the state that are directly related to human activity, indicated by levels of pollutants that exceed natural levels. Due to the presence of these pollutants, all public water supply is strictly regulated and monitored before being delivered for domestic use.

AIR QUALITY

Air pollution is a major concern within urban areas.Transportation, industrial processes, construction, and the combustion of fuels are typical sources of urban air pollution. Sulfur dioxide, carbon dioxide, particulate matter, nitrogen oxide, and carbon monoxide are among the most common urban pollutants which can negatively impact human health, as well as the façades of historic monuments and buildings.

Increases in urban temperatures can affect the rate of the formation, concentration, and distribution of urban pollution, as well as the rate of chemical reaction of airborne pollutants such as ozone. A study of daily peak temperatures in Los Angeles showed a decided correlation between air temperature and the number of days the city exceeds air-quality standards.The US EPA also reported that a 5oF increase in air temperature results in a 10% increase in the number of total pollution-warning days.

Some of the same factors that lead to increased urban temperatures (urban heat island effect) also trap airborne pollutants. City canyons, i.e. the gap spaces between tall buildings and building orientations can create pockets of pollutants sheltered from the wind and result in higher localized air pollution concentrations. Outdoor pollution is also a leading factor in the formation of sick-building syndrome, a term describing indoor air-quality conditions that lead to decreased comfort, productivity, or health of building occupants.The deterioration of older cities can have major implications on indoor air quality (Godish 1989). A list of the potential sources of both outdoor and indoor air contaminants is provided in Table 1-9 below

Table 1-9. Sources of outdoor and indoor emissions and principal

pollutants. (UN Millennium Ecosystems Report 2005)

The Federal Clean Air Act of 1970 requires that all states develop air-quality monitoring networks to characterize and track human health exposure and the effects of criteria pollutants. In 1977, an amendment to this Act mandated that visibility be monitored in certain designated national parks and urban areas.The Phoenix region also monitors visibility year round to assess urban haze.These monitoring networks are comprised of individual stations, as shown in Figure 1-37 and their data helps the Arizona Department of Environmental Quality (ADEQ) bring information to citizens and to other air-quality control agencies.

Criteria Pollutants

The criteria pollutants as indicated by the Clean Air Act of 970, include carbon monoxide nitrogen dioxide, sulfur dioxide, ozone, suspended particulate matter, and total particulate lead.The following list describes these pollutants, their major sources, treatment methods, and trends for the Phoenix region.

Figure 1-37.Ambient air monitoring stations located with in Arizona (Source:ADEQ 2006).

Carbon Monoxide (CO)

A colorless, odorless, and tasteless gas Carbon Monoxide (CO) is the product of incomplete fuel combustion. The adverse health effects of CO results from its ability to chemically bind with blood hemoglobin, blocking oxygen uptake.This reduced oxygen transport can lead to nervous system effects including time-interval discrimination, light sensitivity, increased reaction time, headache, fatigue, and dizziness (ADEQ 2006). Breathing CO also aggravates arteriosclerotic heart diseases. A total of 52% of CO emissions are from on-road motor vehicles and the other 45% are from off-road vehicles used mainly in construction or lawn maintenance.The highest concentrations are found along busy city streets and in neighborhoods where emissions from upwind sources get trapped. CO is inversely related to temperature in combustion engines – the hotter the engine, the less CO is formed.Therefore, the winter months see the highest concentrations of CO.

Figure 1-38. 8-hour CO maxima at 18th St and Roosevelt in central Phoenix. (Source: ADEQ 2006).

During the 1970s and 80s, CO levels in the Phoenix metro area were repeatedly high, exceeding the maximum acceptable level at least 100 times a year. Since 1996, CO levels have declined, attributable to the installation of catalytic converters, electronic-ignition systems, use of oxygenated fuels, and mandatory inspections for vehicles. In Central Phoenix, the monitoring station at 18th Street and Roosevelt has recorded a steady decrease in CO since 1975 (Figure 1-38).

Nitrogen Dioxide (NO )

Nitrogen dioxide, a byproduct of all combustion, is a reddish-brown gas formed by the oxidation of nitric oxide (NO). Respiratory damage such as cilia destruction, alveolar tissue disruption, and obstruction of respiratory bronchioles has been inked to low levels of NO2 In addition to its health effects, NO2 plays a major role in forming ozone (O ) and reduced visibility in Phoenix (ADEQ 2006). Nitrogen oxides are formed from the emissions of cars and trucks (58%), off-road vehicles and equipment (trains and construction machinery), (27%), electric power plants (7%), stationary sources (4%) and biogenic emissions from soil (4%).

Nitrogen oxides from combustion gases are broken up into 95% NO and 5% NO2; however, once in the air, NO quickly oxidizes to NO2 As with carbon monoxide, NO and NO2 are highest near major transit corridors. NO2 tends to peak in the late afternoon and early evening rush hour. Nitrogen oxide can help reduce ozone by chemical reaction at night, reducing ozone levels to near-zero levels.This causes a dip in ozone concentration at night in urban areas along highways as compared to rural areas with lower NO emissions.

Nitrogen-oxide emissions have been greatly reduced over the last two decades due to changes to vehicles like the retardation of spark plug timing, lowering the compression ratio, exhaust-gas recirculation systems, and three-way catalysts, as well as reformation of gasoline and mandatory vehicle-emission inspections.There are currently 11 stations monitoring NO and NOx (NO + NO2) concentrations in Phoenix and Tucson (ADEQ 2006).

Sulfur Dioxide (SO )

Sulfur dioxide, a colorless gas with an irritating odor, can lead to serious environmental and health-related consequences.

SO2 is a leading cause of acid rain, the artificial decrease of rain water pH. Acid rain can severely impact plant growth and sensitive water bodies. Elevated concentrations of SO2 can alter human upper respiratory airway function, including increasing nasal-flow resistance and decreasing the nasal mucus flow rate.This resistance often produces acute bronchioconstriction for exercising asthmatics.The primary source of SO2 emissions in Arizona has historically been the smelting of sulfide copper ore. Most fuels also have small quantities of gaseous SO2 and particulate sulfate, SO4. According to ADEQ, 32% of SO2 emissions come from industrial point sources, 26 % from area sources, 23 % from off-road vehicles and equipment, and 19% from on- oad vehicles.

SO2 is removed from the air by plants through dry deposition. From there, water transforms it into sulfuric acid and then to sulfate. In most cases, concentrations in urban areas around Phoenix are well below the 80 µg/m3 federal standard, and range from 3 to 10 µg/m3.

The major turning point for SO2 emissions in Arizona was in the 1980s when major controls were installed on all copper smelters.Vehicular SO2 and SO4 emissions have also been reduced significantly as petroleum refineries are required to produce reduced sulfur content diesel fuel and gasoline.

Ozone (O )

Ozone is a colorless, slightly odorous gas that can be beneficial or detrimental depending on its location in the atmosphere. In the stratosphere (high above the surface), ozone blocks harmful ultraviolet (UV) radiation and is vital to the health of humans and ecosystems. At the ground level, O is a major pollutant and adversely impacts the health of humans, animals, plants, and materials.The effect of O on humans is both physiological and pathological, and even short exposure periods of < l2 hours to ozone concentrations between 0.1 to 0.4 parts per million can increase respiratory rates and pulmonary resistance, and change lung contraction and expansion (ADEQ 2006).This alteration is particularly severe in exercising adults, shown by signs of throat dryness, chest tightness, substernal pain, coughing, wheezing, pain while breathing deep, shortness of breath, and headache.

Even in low concentrations, O can inhibit the immune systems of animals and severely disrupt plant respiration rates. Signs of damage to plants can appear as specks on the tips of confer needles and upper leaf surfaces of dichotomous plants. Plant scientists consider ozone to be the most damaging urban air pollutant for plants, causing 90% of the damage worldwide (UN

Figure 1-39. Ozone formation in an urban environment (Source: Houston Advanced Research Center and the National Resource Council Report on Ozone 1991).

2005). Ozone is the product of a photochemical reaction involving volatile organic compounds, nitrogen oxides and sunlight. Volatile organic compound (VOC) emissions in Phoenix are from: cars and trucks (31%), off-road vehicles and equipment (27%), small stationary sources (20%), biogenic emissions including grass, shrubs and trees (17%) and point sources (5%). (ADEQ 2006). Figure 1 39 shows the various interactions that lead to O formation in the urban environment.

Ozone concentrations are regularly present during the day in urban and rural areas, and peak during the summer months when sunlight, biogenic emissions, and evaporative hydrocarbon emissions peak. After sunset, O formation drops to almost zero due to the absence of photons from the sun, but quickly increases during the morning and afternoon. Efforts to reduce ozone and smog formation focus on the major precursors VOC and NOx. Engine modifications, catalytic converters, improved fuel tanks, carbon canisters in the fuel lines, vehicle inspections, and modifications to gasoline are being used. Despite these efforts, meeting the ozone eight-hour standard has been difficult.

As of 2005, there were 35 air-quality stations reporting ozone scattered around the state of Arizona, mostly in urban neighborhoods and within close proximity of sources.

Figure 1-40. Maximum 1-hour ozone concentrations in Phoenix, Tucson and Yuma, AZ, 1980–2006

(Source: ADEQ 2006).

Maximum one-hour ozone concentrations have declined in Phoenix since the 1980s (Figure 1-40). Phoenix experienced a 32% decline over the last 25 years, and the ozone standard has not been exceeded since 1996.This decline can be attributed to the implementation of many exhaust controls for automobiles.

Particulate Matter (PM)

Particulate matter (PM) is a very important air pollutant in Arizona. Particulate matter are very small solid and liquid particles that vary widely in size, geometry, chemical composition and physical properties. PM reduces visibility and affects public health. Sources of PM can be both natural and human induced. Pollen and wind can release particulates into the air while more anthropogenic sources might include soot, fly ash, and dust from both paved and unpaved roads. PM2.5 which indicates fine particles of less than 2.5 microns in aerodynamic diameter, can be formed by agglomeration or coagulation in vapors, so they are often emitted during combustion or soils mixing. Larger, coarse particulates ranging in diameter from 2.5 to 0 microns are formed from direct grinding of materials and soils. Coarse emissions are comprised of dust caused by:

• re-entraining dust from paved roads
• driving on unpaved roads
• earthmoving associated with construction

These three activities cause 70% of all coarse particulates in Phoenix.

Figure 1-41. Three-year moving average of annual average PM10

at four metro Phoenix sites with moderate PM10 levels (Source: ADEQ 2006).

Health effects differ by the size and shape of the particulates. Large particulates (> 10 microns) are caught in the upper respiratory tract while smaller particulates (2.5 to 10 microns) can be inhaled and are deposited in the lower respiratory system, more damaging because are so small that they are respirable, entering the pulmonary tissues and remain there.

In 1995, the Arizona Comparative Environmental Risk Project ranked particulate matter as the highest environmental health risk in the state.The study estimated 963 premature deaths a year were caused by exposure to PM10 concentrations. In 1991 Maricopa County had 667 deaths attributed to PM, compared to 88 for Tucson. Increases in respiratory disease, asthma, and coughs were also due to the elevated PM10 levels in that year.The relative levels of particulate matter differ by location in the city. Although PM2.5 is found in most areas, concentrations are typically higher in the urban center due to moving vehicles disturbing fine road dust, but are also seen on the urban fringes where construction and land development is occurring.

To reduce coarse particulates, Maricopa County created Rule 310, the dust-abatement rule.This rule regulates dirt moving and track-out dust from construction sites, and dust from unpaved parking and vacant lots. Fine particulates have been reduced because of stiffer vehicle regulations on the precursory elements that form particulates.

Figure 1-42. Average best and average worst visibility in Phoenix (Source: ADEQ).

Visibility

Visibility in Phoenix is an important air quality indicator, and an obvious signal of air quality conditions for residents.Visibility or more specifically the extinction of light as it passes through the atmosphere, is influenced by a variety of factors, and ozone and particulate matter have the greatest bearing on visibility in Phoenix. Figure 1-42 shows how a clear day in Phoenix compares with an ‘average visibility day’.The highest visibility days are usually on weekends with steady breezes.The lowest visibility days are often weekdays with their increased vehicle road miles and weekday construction activities which add to particulate matter and ozone formation.

Although visibility in Phoenix has not had as drastic an improvement as those of other criteria pollutants, there has been a steady improvement since the late 1990s. In general, the visibility during the dirtiest 20% of days increased by 7% since 1994 This improvement rate is much slower (3%) for the mean and cleanest days (2%) as evidenced in Figure 1-43. I

Figure 1-43. Light extinction trends in Phoenix (Source: ADEQ 2006).

Despite the rapid urbanization in the Phoenix region, pollutant levels continue to decline. Most national criteria pollutant air quality standards have been met since 1997, with the notable exception of eight-hour ozone standards during the summer months and the PM10 standards near construction-dominated areas.This improvement in air quality in Maricopa County directly results from federal and local air quality control programs, and shows how government programs positively affect the urban environment and sustainability in the Phoenix region.

NOISE POLLUTION AND ACOUSTIC COMFORT

The United Kingdom (UK) has been a leader in noise reduction legislature and has produced research that finds that noise levels of 40 – 55 decibels is annoying to receptors, that at levels between 55 and 60 decibels sleep is disturbed, and levels of 70 decibels can affect health and school performance.

A long running UK study published in 2007 named the ‘Attitudes to Noise from Aircraft Sources in England’ (ANASE) concluded that even relatively low levels of noise can cause annoyance and that:

“…noise from (transport and industrial) sources can cause conversation to be disrupted, sleep disturbance or simply generate feelings of annoyance. Consequently, the enjoyment of homes, gardens and open spaces can be adversely affected by this environmental noise. Concern has been raised about the effects of noise on mental health, cardiovascular and physiological functions and the effects on performance such as learning acquisition by children”.

A seven month investigation in 2002 – 2003 by Maidstone Borough Council studied effects from two major highways, M2 and M20 corridors in Kent, England. The study found that measured highway sound levels were significantly above what had been expected, registering up to 60 to 70 decibels, and enough to alter pupils’ school performance and disturb the sleep of esidents

The British Medical Journal released an abstract regarding noise pollution in 2003 which summarized that “Noise interferes in complex task performance, modifies social behavior and causes annoyance. Studies of occupational and environmental noise exposure suggest an association with hypertension… and in children chronic noise exposure impairs reading comprehension

and long term memory and may be associated with raised blood pressure”. The World Health Organization website states that heath risks identified with noise includes “interference with social behaviour, such as aggressiveness, protest and helplessness”.

Concerns of noise from highways have often been overshadowed by investigations into noise pollution from airports. In early 2004 the Mayor of London issued the ‘Ambient Noise Strategy’ requiring review of noise from railroads, airports, highways and streets and industrial plants.The study estimates that:

• 54% of the population of the UK lives in dwellings exposed to external daytime noise levels above 55 decibels,
• 67% of the population of the UK lives in dwellings exposed to external night time noise levels above 45 decibels.

A result of this study effort was the issuance of ‘The Environmental Noise (England) Regulation of 2006’ regulating noise sources above 55 decibels in outside settings. Also noted, prior to the implementation of this Directive, noise tended to be assessed only when a change to transportation or industrial was expected to occur.The European Union has also begun to regulate outdoor machinery and has produced ‘noise labeling requirements’ for equipment.

Further analysis to noise has produced statements that this is considered a social equity issue, with high percentages of noise suffers are “poor people in noisy neighborhoods, suffer from ‘unacceptably’ high noise levels”. The ‘Community Noise Research Strategy Plan’ (CALM) from the publication ‘Research for a Quieter Europe in 2002’ outlines study and strategy for road transport, railway, air traffic, maritime transport and outdoor equipment.

The City of Phoenix began using rubberized asphalt pavement in 1964, reducing noise levels from City Street traffic an average of 3 to 5 decibels, although reductions of 10 decibels have been noted. Highway noise barriers as mitigation strategies cut the sound that reaches homes by 10 – 15 decibels.

Recently, Arizona Department of Transportation (ADOT) began the ‘Quiet Pavement Pilot Program’ an aggressive 115 mile rubberized asphalt paving program estimated to cost $34M. Rubberized asphalt reduces noise in the 500 to 4,000 Hertz frequency band.

ADOT noise criteria sets acceptable limits for highway noise as:

• Sensitive park land – 57 decibels (‘A’ Category’);
  • Typical parks, homes, churches, schools, libraries, hospitals – 67 decibels (‘B Category’);
• Other developed land – 72 decibels (‘C Category’);
• Interiors of home and community buildings – 52 decibels (‘E Category’).

Overall, ADOT states its goal is to reduce noise levels to 64 dBA , lower than the Federal noise abatement criteria of 67 dBA outlined in the Federal Highway Administration Noise Abatement Criteria (23 Code of Federal Regulations Part 772). Several issues have been noted with these regulations and policies: only homes or community areas within 1000 feet of the highway right-of-way are considered in these analysis or factored into any mitigation action; any mandated soundproofing has a goal to reduce noise only 5 decibels ‘where feasible’; and rubberized asphalt does nothing to reduce noise in the lower Hertz frequencies.

Low frequency noise (LFN) is generally defined as noise in the 100 to 150 Hertz range and is sometimes referred to as ‘infrasound’. LFN is now a recognized problem in many developed countries and there is considerable interest in this newly recognized phenomenon and its often powerful health effects. While there are numerous articles on the effects of LFN on marine life, study of human health effects is fairly new.

The Federal Aviation Administration (FAA) requires assessment of noise surrounding airports, culminating in a ‘Part 150’ study which produces mapping of the noise level contours from aircraft activities. The FAA can use federal funds for interior sound mitigation of homes, schools, churches and other community buildings that are impacted with noise above the 65 decibel level. Airport and community activists have promoted the reduction of the 65 dBA level to 60 or even 55 dBA level, but to date the FAA has not agreed.

Urban Climate Change

As the Phoenix region has transformed from desert and rural agriculture to urban built environments, many factors have induced climatic changes. Native vegetation, a source of evapotranspiration and shade, is removed during this land conversion. Next, engineered materials used to provide shelter, mobility, sanitation, and culture are set in place to form the urban setting (Golden 2004).These foreign materials often reflect less of the sun’s energy (lower albedo), are impervious (preventing natural water migration through the soil and impacting air flows), and alter radiative characteristics by their geometry, size, and orientation.These surface materials include streets, roofs, walls, lawns, landscaping, and parking lots.The impact of urbanization is increasingly important not only within the urban core but in regions that surround and supply necessary resources such as energy and water (McMichael et al. 2002).

Figure 1-44. The regional UHI effect for maximum day time and minimum nighttime temperatures over different land covers. Source: Zehnder et al. 2004

One of the more prevailing issues facing rapidly urbanizing regions is the increase in average minimum temperatures that appears to correlate to urban growth (Figure 1-44).This phenomenon, known as the Urban Heat Island (UHI) Effect, can be observed in metropolitan areas around the world. UHI is particularly evident and detrimental in arid urban regions.

Historical Overview of Phoenix’s Urban Heat Island

The UHI in Phoenix is one of the strongest in the world, with an increase of 0.860F per decade since the 1960s (Brazel et al. 2000). As presented in Figure 1-45, average regional temperatures have increased 5.6°F over that time period, but a threefold increase has occurred in the region’s urban areas. Over the last 50 years, the average difference between minimum

ambient air temperatures of rural and urbanized areas of Maricopa County has increased by 8ºF. In extreme instances, such as highly developed areas with minimal vegetation, this difference is as much as 15ºF at night (Brazel et al. 2007).

Figure 1-45. The increasing Phoenix UHI effect as a function of population growth and urbanization (Golden 2004).

It is important to distinguish between a nighttime (post-sundown) UHI effect and a daytime UHI effect. Depending on the location being examined, the Phoenix region actually experiences both a daytime and nighttime UHI effect.

The plots in Figure 1-46 are daytime and nighttime ground level (< 3m height) air temperatures observed in Phoenix. Note that the urbanized areas and the surrounding desert reach similar temperatures during the day. At night, the UHI is much more pronounced, and areas shown in yellow indicate warm temperatures and correspond with Phoenix’s downtown area.

Figure 1-46. Surface temperature plots of the Phoenix area showing the difference between (a) day and (b) night. (Source: Balling and Brazel, 1989).

Figure 1-47. Three locations used for comparison of air-temperature variations in the Phoenix area: highly vegetated Encanto Park, Sky Harbor International Airport, and the primarily agricultural City of Maricopa (Source: Google Maps 2006).

(Baker, L.. el. al. 2002)

As will be discussed in Chapter 3, there are alternative material and spatial designs that can directly affect the intensity of the UHI effect in a given location at a given time of the day.

Air temperatures at Sky Harbor International Airport are often among the warmest in the Phoenix area, likely due to the large mass of pavements required to support aircraft traffic. A recent study conducted by ASU compared the average diurnal temperatures of three locations in and around the Phoenix area.The three locations—Encanto Park, Sky Harbor Airport, and the town of Maricopa—are at the same elevation.Their spatial relationship is indicated in Figure 1-47.

Figure 1-48. Comparing average monthly diurnal air temperatures among three locations in the Phoenix area during (a) January and (b) June 2004. In both instances average air temperature is 10oF higher at Sky Harbor Airport than in Maricopa at 5 am, even though the peak daytime temperatures are almost the same (Source: AZMet and ASOS 2004).

The image on the left in Figure 1-49 was taken of the Phoenix region from an ASTER Satellite at 11pm one night in October 2003, with colors representing surface temperature.The image on the right of Figure 1-49 highlights the hottest 20% of the surfaces in the same location. Certain surfaces stand out more than others: the mountains, downtown Phoenix the airports, major city streets, and highways are clearly visible in both images.The thermal properties of concrete and asphalt behave similar to the dense granite mountains, capturing and storing solar energy. In a city spread out like Phoenix, the primary causes of the UHI effect is increased thermal storage created by urban materials and the loss of evapotranspiration due to the loss of native vegetation.

Figure 1-49. The role of materials to the UHI. On the left, is a satellite image from 10/3/2003 at 0 pm of the three-county region with yellow depicting the hottest surface temperature. On the right, is the same image showing the top 20% of surface temperatures in red.The role of pavements and buildings in the urban area is significant. (Source: Arizona State University)

Contributing Factors

The climate within cities is quite complex, with many factors contributing to its behavior within an urban area. Oke et al. (1997) summarized the most critical factors that differentiate urban areas from natural land cover and lead to elevated temperatures within urban centers.

Canyon Geometry – Buildings form “canyons” that tend to trap thermal energy near the bottom surface

Thermal Properties – The materials, concrete, asphalt, roofs, and walls tend to be denser and absorb and retain more thermal energy than natural surface cover.

Anthropogenic Heat – Heat released from the combustion of fuels, electrical energy used for lighting and driving motors, and human and animal biological metabolism can elevate the temperature in dense urban areas.

The Urban Greenhouse Effect – Warmer air and air pollution within cities acts as a microgreenhouse effect, preventing heat from radiating from the warmed surfaces.

The Effective Reflectivity (Albedo) – The total reflectivity of a city is reduced due to the trapping of short-wave radiation by its building canyons.

Reduction of Evaporating Surfaces – As a city expands, natural vegetation is removed at a greater rate than it is replaced.This loss of moisture can adversely affect temperatures within the city.

ReducedTurbulentTransfer of Heat – In some areas of the city, wind patterns can actually be blocked, causing pockets with little wind flow and mixing.This reduced mixing of air greatly reduces the heat released from streets.

The images in Figure 1-50 and Figure 1-51 were taken using an infrared camera from a helicopter at 3 and 10 pm during Summers 2006 and 2008.The images show the contrasting surface temperatures found at night within different urbanized areas of Phoenix. Areas adjacent to tall buildings have lower sky-view factors, reducing the ability of heat to dissipate, and are made of dense concrete, which lead to their increased temperatures after sunset.These are just a few examples of the thermal complexity within urban settings.

Figure 1-50. Handheld infrared thermographic image of downtown Phoenix, Arizona at 3pm on April 4, 2008. (Source: Arizona State University).

Figure1-51.Helicopter infrared imagery of typical Phoenix land uses showing the role of pavements.Yellow is warmest, purple shows coolest temperatures, images taken at approximately 10pm July 2006. (Source: National Center of Excellence on SMART Innovations).

Urban Surface Energy Balance

“Understanding the nature of energy partitioning at the surface of cities is prerequisite to gaining proper insight and ability to model their climatic environment” (Roberts et al. 2003).

According to a study that compiled the results of several studies in various urban centers around the globe, the urban surface energy balance (USEB) is expressed theoretically as follows;

QI + QF = QH + QE + ∆QS + ∆QA

Where QI is net all-wave solar radiation, QF is the anthropogenic heat flux (car exhaust, light bulbs, etc), QH is the sensible heat flux, QE is the latent heat flux, ∆Qs is the net storage flux, and ∆QA is the net horizontal heat advection (Roberts et al. 2003).The ∆Qs, the term representing urban energy storage flux, is of the greatest relevance to the urban environment because it is shown to account for over half of the daytime net radiation at highly urbanized sites, including St. Louis and Mexico City (Ching 1985). ∆Qs is dependant on both the materials and geometries of the urban surface and nocturnal heat energy release is thought to be the major variable in the hysteresis lag effect that creates the UHI (Roberts et al. 2003). Though ∆Qs is agreed to be the most critical term in the USEB, it is significantly understudied.The complexity and three- dimensional aspect of the urban surface makes it a difficult challenge to accurately measure.

Researchers at Arizona State University (ASU) and other universities are working on improving the methods and input variables required to model the UHI formation and its impacts. With accurate modeling capabilities, city officials may someday be able to understand the broader impacts and benefits of policy decisions regarding UHI mitigation and energy use.

Figure 1-52. Urban surface energy balance fluxes (Golden 2004).

Impacts of Urban Heat Islands

The UHI can have several impacts on the three imperatives of sustainable development: environment, economic, and social well being.The most prevalent impacts of elevated temperatures include air quality, thermal comfort, energy consumption, water use and loss, tourism and business, agriculture production, vehicle efficiency, and weather patterns (Figure 1-53).

Figure 1-53. Impacts from the UHI effect. (Golden 2004).

Air Quality and Urban Heat Islands

When increased surface and ambient air temperatures combine with ultraviolet radiation and a mixture of nitrous oxides (NOx) and volatile organic compounds (VOCs) the result is the formation of ground level ozone. Urban centers in arid and semiarid regions with congested traffic often deal with the rapid formation of smog as ambient temperatures rise (EPA 2001).

The elevated air temperatures within urban centers can also lead residents to run air conditioning systems at higher rates and for longer periods of time, increasing the demand for energy production.The power plants supplying the power required for these cooling systems often emit aerosolized compounds that can contribute to smog formation.The plot in Figure 1-54 shows this correlation between energy demand and smog generation as average afternoon temperatures increase.

Figure 1-54. Energy consumption and smog production vs. afternoon temperatures in Los Angeles. (Source: US EPA).

Energy and Urban Heat Islands

UHI also increases the consumption of electricity and the risk of a major disturbance in energy delivery due to the UHI- induced increase in mechanical cooling needs. Commercial and residential buildings use 65.2% of total US electricity and 36% of total US primary energy. Research in the Phoenix area has directly related the continued increase in electricity consumption dating from 1948, due to urban climate change. Architectural energy modeling conducted at ASU concluded that a typical residence in Phoenix (using conservative 2002 construction technologies) would experience an increase from 7,888 annual kWh in 1950 to 8,873 kWh in 2004 when accounting for the urban-climate change during that same period. Additionally, in US cities with populations over 100,000, peak-utility loads increased 1.5-2.% for every 1°F (0.6°C) increase in summertime temperatures (EPA 1992).

A Lawrence Berkeley National Laboratory (LBNL) and Department of Energy (DOE) study in Los Angeles concluded that about 1-1.5 Gigawatts of power are used to compensate for these increases in urban-climate temperatures.This amount is equivalent to the combined power used annually by 400,000 average US homes.This increased power needs cost the Los Angeles ratepayers about $100,000 per hour and about $100 million per year. On a national basis, the cost avoidance for electricity and the associated emissions was estimated at $5B/year.The increase of fossil fuels burned, water consumption, water discharges, air emissions, and waste generation at the power plants also acts upon the system.

Economics and Urban Heat Islands

Research has indicated that if UHI mitigation strategies could realize a 1.8°F to 3.6°F decrease in average temperature in urban settings, the annual energy savings could reach $26 million for three demonstration US cities (LBNL 2000). In areas of high-solar capacity, such as the desert Southwest, modeling the adaptation of renewables such as photovoltaics as a mitigation strategy merits consideration

Water and Urban Heat Islands

Up to 40 gallons (140 liters) of water is required to produce 1kWh of electricity from a coal plant and 54 gallons (205 liters) for nuclear-powered plants. Approximately 408 billion gallons per day were withdrawn for all uses in the US during 2000. Fresh groundwater withdrawals (83.3 Bgal/d) during 2000 were 14% higher than in 1985. Approximately 195 Bgal/d, or 48%, of all freshwater and saline-water withdrawals for 2000, were used for thermoelectric power. Most of this water was derived from surface water and used for once-through cooling at power plants.

Alteration of water temperature in urban stormwater runoff, from contact with increased surface temperature of pavements can play a significant role in the chemical and biological processes that support water quality. In urbanized watersheds, nonpoint source runoff is considered to be a major general source of many pollutants, and the percentage of impervious surface area has been documented to be an important factor in determining receiving stream water quality as defined by ecological indicators such as benthic macroinvertebrate community composition and fish density and abundance. Water-resource protection at the local level is increasingly complicated, largely due to the importance of nonpoint source pollution, or polluted runoff.This diffuse form of pollution, now the nation’s leading threat to water quality, results from contaminants that are washed off the surface of the land by stormwater and are carried either directly or indirectly into waterways or groundwater.

Excessive Heat Events and the Urban Heat Island

One of the most significant impacts from the UHI effect relate to human health. During extended periods of excessively high temperatures, called heatwaves, the UHI can make it difficult for citizens to escape the heat at night. During August 2003, one of the largest fatal disasters occurred in one of the most developed regions in the world.

Between 22,000 and 35,000 people died across developed Europe as a result of excessive heatwaves. Heat-related illnesses kill more people in the US than hurricanes, tornadoes, earthquakes, and floods combined. In France in 2003, most of the 4,800 deaths occurred in the urban region of Paris. Similarly, in Chicago in 1995, heatwaves killed 739 people.The victims of heatwaves are usually already in compromised physical states such as the elderly or young. In addition, the homeless and impoverished are often susceptible to heat stress due to lack of air conditioning, water availability, and health services.

Phoenix has an average of 89 days per year of greater than 100oF (37.8ºC) and has experienced 143 days of greater than 00ºF (37.8ºC) temperatures as recently as 1989 (National Weather Service 2008).The region also has the potential of reaching extremely hazardous temperatures as high as 122ºF (50 ºC) in 1990 and 121oF (49.4ºC) in 1995 (Golden 2004). Figure 1-55 includes a bar graph showing the numbers of deaths in Arizona related to heat over a 10-year period.

Figure 1-55. Deaths from exposure to excessive climatic heat occurring in Arizona from 1992-2002 Source: AZ Department of Health Services

Transportation in Urban Areas

Transporting individuals, goods, and services from one structure to another is a daily occurrence to accommodate commerce, social interaction, and public safety.Transportation in urban areas presents a challenging combination of the environmental, social, and economic concerns within the urban environment. Energy use for transportation is the fastest growing energy sector in the world. Most of this increased demand for motor vehicles will be in urban areas. Adversely, this

Figure 1-56. Congestion costs and traffic delays per person per year in the Phoenix area from 1986-2000 Source:Texas Transportation nstitute and US EPA

added mobility comes at an environmental cost. Motor vehicles are the primary cause of traffic congestion and air pollution in cities. In cities similar to Phoenix, the distances between residential areas and the business and industrial sectors make owning and driving a motor vehicle appealing and even essential. In turn, this need, creates a cycle of social inequities by limiting the mobility and access to jobs for those that can not afford vehicles. Although bus transportation is available, due to spatial layout it is not always easily accessible and requires long trip times. In developed countries like the US, 75% of all car trips are less than 10 km (6.23 miles) with the typical car emitting almost 5 tons of CO2 a year (Climate Change Canada 2003)

Traffic congestion has become a major problem in the Phoenix area. Research by the Texas Transportation Institute examined the cost of congestion per person. Figure 1 56 shows that the annual cost of congestion for Phoenicians has grown by $408 per person from 1986 to 2000, which equates to an average of 28 hours of delay annually per person: a 367% increase! To describe this in more graphic terms, the average driver in Phoenix today loses about three days of work time a year sitting in traffic compared to a driver in 1986.This trend has major quality of life implications for Valley residents.

Summary

The region surrounding Phoenix, Arizona has experienced a rapid growth in population and resulting urbanized areas in recent decades. Many people are drawn to the area for a better quality of life – seeking a lower cost of living, pleasant year round weather, and economic and educational opportunities. Citizens are beginning to realize that this growth comes at a cost and if unchecked, may result in a decrease in the quality of life that originally brought them here. The transformation from rural to urban provides many benefits and opportunities for residents, but it also places new pressure on the ecological and infrastructure systems on which we rely. The resulting stress can have severe and irreversible consequences that will ultimately impact our way of life.

A new train of thought is beginning to take hold globally that seeks to mend the disconnect between the natural and built environment. It acknowledges the importance of economic development while also accepting the limits of the earth’s ecosystems, and understands that the actions we take today can negatively or positively affect future generations and their quality of life.This new paradigm is referred to as Sustainable Development and this idea aims to balance the three over- arching objectives of economic, environmental, and social prosperity.

In this chapter we explored several key urban sustainability issues related to the rapid growth in the Phoenix Region

– including energy generation and use, water quality and quantity, transportation, air quality, waste generation, noise pollution and local climate change. The most important aspects of each issue are summarized below.

Energy

The historical and projected energy generation and consumption patterns of the region are on an unsustainable trajectory due to the over reliance on non-renewable energy sources for electrical power and transportation. The primary source of electrical energy is from coal burning power plants, which release the green house gas carbon dioxide (CO2). Our buildings are not as efficient as they could be, wasting energy on artificial light and air conditioning poorly insulated spaces. And while many suggest solar energy as the obvious savior for our state’s energy needs, it still remains economically out of reach.

The gasoline on which our daily commutes depend is derived from locations far outside of the state, and our reliance on personal automobiles will likely continue into the future due to the spread out nature of the city and the lack of a robust public transportation system. Several measures are underway to increase accessibility, speed, and safety of public transportation in the Valley.The Valley’s first light rail system is due to open in 2008 and the public bus networks are also continuing to grow. Even with these additions, we are still far from having a system comparable to many of the nation’s prominent metropolitan areas.

Water

Water quality and quantity will always be a concern in a dry desert region. The early landowners foresaw this limit to growth and constructed a network of canals and dams to control and deliver water from the northern fringes of the state.

These measures may have bought us time but the limits of this supply is inevitable and demands an immediate and drastic shift in the way we use, allocate, and reuse water within the state.

Emissions

Since the 1970s, harmful air and water emission concentrations in the Valley have been steadily declining thanks to regulations and programs set forth by the Arizona Department of Environmental Quality and the Environmental Protection Agency. Nevertheless, air emissions from automobiles and construction have kept ground level Ozone (O ) and Particulate Matter (PM) concentrations at the higher end of the acceptable levels. Naturally occurring water contaminants such as Arsenic (As) and historical chemical releases from industrial facilities remain a threat to underground water resources in rural and urban areas of Arizona

Waste

The amount of solid waste continues to increase with population, but the relative percentage of waste that is diverted or recycled has been helping to slow this trend. Curbside recycling began in the early 1990s in Arizona and has had positive results, but there remains plenty of room for improvement. Public awareness, convenience, incentives and regulation are key components of managing and reducing waste as we move forward.

Urban Climate

The expansion of urban areas in the region have lead to the removal of vegetation and the construction of countless new roads, parking lots and buildings made of dense and often dark materials. These engineered materials capture and store the sun’s energy more readily than natural materials, resulting in warmer air temperatures at night.This phenomenon is known as the Urban Heat Island (UHI) effect and impacts the amount of energy and water we use, the amount of smog in the air,

and our overall enjoyment and comfort within the city. This phenomenon occurs in nearly all urban areas, and the magnitude of the Phoenix UHI is particularly severe.The average night time low in Phoenix has increased by 8ºF over the last 50 years (Brazel 2000). Research is being conducted to help reduce these effects, and in the following chapter, Urban Heat Island Mitigation, we provide detailed information about the latest materials and design strategies that planners and designers can use to help mitigate urban heat island effects within cities.

Moving Forward

The topics discussed in this chapter were focused on the environmental problems of urbanized regions.There are, of course, many equally important economic and social problems that our region continues to struggle with. Issues of immigration, the housing market, health care, drug abuse, crime, education and employment affect us all and require our constant diligence and attention. Many governmental and non-governmental organizations have been working for decades to address these issues Sustainable development can be the uniting ideal that brings these efforts into a single trajectory, forming a powerful force as we progress into the future.

Our intention in writing this guidebook was not to provide solutions for all of the world’s problems but rather to focus on the ones that are within the realm of city planners, architects and engineers. And in providing an overview of the most pressing issues, we can hope that future development in the region will be guided by the principles and ideals of sustainable development in the Phoenix region.

Additional Resources

World Business Council for Sustainable Development:

www.wbcsd.org/templates/TemplateWBCSD5/layout.asp?MenuID=

US EPA National Risk Management Research Lab’s Life-Cycle Assessment: www.epa.gov/ORD/NRMRL/lcaccess/index.htm

SO Standards www.iso.ch/iso/en/CatalogueListPage.CatalogueList?ICS1=13&ICS2=020&ICS3=10

UN Life Cycle Initiative: http://lcinitiative.unep.fr

Life Cycle Assessment for Cities: www.gdrc.org/uem/lca/lca-for-citie.htm

Portland Cement Association www.cement.org/buildings/sustainable_lca.asp

National Center of Excellence on SMART Innovations for Urban Climate and Energy: www.asuSMART.com

EPA Energy Star: www.energystar.gov/index.cfm?fuseaction=find_a_product

US Green Building Council: www.usgbc.org

Green Roofs www.greenroofs.com

National Asphalt Pavement Association: www.hotmix.org American Concrete Pavement Association www.pavement.com Lawrence Berkeley National Lab: http://eetd.lbl.gov/heatisland DOE’s Home Energy Saver: http://hes.lbl.gov

eQUEST: http://doe2.com/equest/index.html

DOE2 Energy Model: http://doe2.com/DOE2/index.html

Air Explorer: www.epa.gov/airexplorer

AirWeb Protecting Air Quality: www2.nature.nps.gov/air Arizona Department of Environmental Quality: www.azdeq.gov Earth 911 Making Every Day Earth Day: www.earth911.org

Earth’s Biggest Environment Search Engine: www.webdirectory.com

Environmental Protection Agency: www.epa.gov EPA – Air and Radiation: www.epa.gov/oar/oaqps EPA’s – AIRNow: www.airnow.gov

EPA’s Air Quality Database: www.epa.gov/air/data/index.html

Software

Athena LCA Software www.athenasmi.ca

Boustead Consulting Database and Software

ECO-it Eco-Indicator Tool for environmentally friendly design – PRé Consultants

EDIP – Environmental design of industrial products – Danish EPA

EIOLCA – Economic Input-Output LCA at Carnegie Mellon University

GaB – Product Family (Ganzheitlichen Bilanzierung – holistic balancing) – Five Winds KCL-ECO 3.0 – KCL LCA software LCAiT – CIT EkoLogik (Chalmers Industriteknik)

SimaPro 7 for Windows – PRé Consultants

Tools for Environmental Analysis and Management (TEAM) – Ecobalance, Inc

Umberto – Advanced software tool for Life Cycle Assessment – Institut für Umweltinformatik

Building Life-Cycle Cost (BLCC) Program, version 5.2-04 – Economic analysis tool developed by the National Institute of Standards and Technology for the DOE Federal Energy Management Program.

Energy-10 – Cost-estimating program of the Sustainable Buildings Industry Counci

The Tri-Services Parametric Estimating System (TPES) contained in the National Institute of Building Sciences (NIBS)

Construction Criteria Base developed models of facility types by determining critical cost parameters

(i.e., number of floors, area and volume, perimeter length) and using these values to predict the costs of a wide range of building systems, subsystems, and assemblies.The TPES models can be adapted to facilities beyond those included in the base- modeling system by using SuccessEstimator, a software package available from US Cost.

References

ADEQ, 2000.The Status of Water Quality in Arizona, Clean Water Act Section 305(b) Report 2000. ADEQ Environmental Quality Report EQR-00-03.

ADEQ, 2002. Groundwater Protection in Arizona: An Assessment of Groundwater Quality and the Effectiveness of Groundwater Programs. A.R.S. §49-249.

ADWR, 2002. ADWR Website: Arizona’s Water Supplies and Water Demands. http://www.adwr.state.az.us/AZWaterInfo/statewide/supplyde.html

ADEQ, 2006. Air Quality Annual Report, A.R.S. 49-424.10.

Allenby, B.R. 1999. Industrial Ecology: Policy Framework and Implementation. Upper Saddle River, NJ: Prentice Hall.

Arnfeld, A.J., Herbert, J.M. and Johnson, G.T. (1999). Urban Canyon Heat Source and Sink Strength Variations: A Simulation-Based Sensitivity Study Congress of Biometerology and International Conference on Urban Climate, WMO: Sydney

Arwood, J. (2006). Solar Power is Sizzling Hot. Tech Connect Magazine 2, 36 – 40

Baker, L. et. al. (2002). “Urbanization and Warming of Phoenix (Arizona, USA): Impacts, feedbacks and mitigation.” Urban Ecosystems 6:183-203

Baker, L. , Brazel, Anthony, J., Westerhoff, P. (2004). Environmental Consequences of Rapid Urbanization in Warm, Arid Lands: Case Study of Phoenix, Arizona, the Sustainable City III, Advances in Architecture Series, WIT Press, Boston.

Balling, R.C., Brazel, S.W., (1989).Time and space characteristics of the Phoenix urban heat island. Journal of the Arizona-Nevada Academy of Science, 21, pp. 75-81.

Bartone, Carl, “Annotated Outline of a Report on Strategic Options for Managing the Urban Environment” Washington DC: World Bank, 1991

Baruska,T. and W. McClure, 2007.The Built Environment: A Collaborative Inquiry Into Design and Planning,

Bass, B., Krayenhoff, S. & Martilli, A. (2002). Mitigating the Urban Heat Island with Green Roof Infrastructure Urban Heat Island Summit:Toronto

Brazel, A., Selover, N.,Vose, R., and Heisler, G. (2000).The tale of two climates-Baltimore and Phoenix urban LTER sites. Climate Research Vol. 15: 123-135, 2000

Brazel, A. J., Gober, P., Lee, S., Grossman-Clarke, S., Zehnder, J. and Hedquist, B. (2007) Dynamics and determinants of urban heat island change (1990-2004) with Phoenix, Arizona USA. Climate Research 33:2 , pp. 171-182.

Bretz, S., Akbari, H. (1997). Long-term Performance of High-Albedo Roof Coatings. Energy and Buildings – Special Issue on

Urban Heat Islands and Cool Communities, 25(2), pp. 159-167.

Bruntland, H.G. (1987). Our Common Future, WCED. New York: Oxford University Press. Carson, Rachel L. (1962). Silent Spring 40th Anniversary Edition First Mariner Books edition 2002

Ching, J. K. S. (1985). “Urban-scale variations of turbulence parameters and fluxes.” Bound.-Layer Meteor., 33 (4), 335-361.

Decker, E. H., Elliott, S., Smith, F., Blake, D. and F. S. Rowland (2000). Energy and Material Flow Through the Urban Ecosystem..

Energy Environment 25:685-740

Energy Information Administration (2007). Annual Energy Review. US Dept of Energy, Washington, D.C. <www.eia.doe.gov/ emeu/aer/contents.html>

Erlich, Paul R. (1968). The Population Bomb New York: Ballantine Books

Ewing, R.. Pedestrian and Transit Friendly Design: A Primer for Smart Growth. June 1999. Smart Growth Network.

Feely,T. J., Hoffman, J., and B. Carney (2005). Power plant water management—A Department of Energy/National Energy Technology Laboratory R&D Initiative.

Golden, J., Brazel, A., Salmond, J., and D. Laws (2006). Energy and Water Sustainability – The Role of Urban Climnate Change from Metropolitan Infrastructure. Engineering for Sustainable Development Vol. No. 1, pp. 55-70.

Golden, J. (2004). “The Built Environment Induced Urban-Heat-Island Effect in Rapidly Urbanizing Arid Regions – A Sustainable Urban Engineering Complexity.” Environmental Sciences, 2003/2004,Vol. 1, No. 4, pp. 321–349

Godish,T. (1989). Indoor Pollution Control. Lewis Publishers. Chelsea, Michigan.

Graf, Charles G., 1986.VOC’s in Arizona.s Groundwater; A Status Report. Proceedings of the Focus Conference on Southwestern Groundwater Issues, National Water Well Association, Oct. 20-21, 1986.

Grimmond, C.S.B and Oke,T.R. (1999). Aerodynamic properties of urban areas derived from analysis of surface form. Journal of Applied Meteorology 38, 1262-1292

Hall, J., and H.Vredenburg (2004). “The Challenges of Innovating for Sustainable Development”. MIT Sloan Management Review

Herzog, H.J., Drake, E.M., and E.E. Adams (1997). CO2 Capture, Reuse and Storage Technologies for Mitigating Global Climate Change. DOE Order No. DE-AF22-96PCO1257. Cambridge: MIT.

Heisenberg, W. (1927). Uber den anschaulichen Inhalt der quantentheoretischen Kinematick und Mechanik, in Zeitschrift fur Physik pp. 172-198, volume 43.

Howard-Grenville, Jennifer A. (2001). Institutional Evolution.The Case of the Semiconductor Industry Voluntary PFC Emissions Reduction Agreements. Organizations, Policy and Natural Environment: Institutional and Strategic Perspectives. Palo Alto: Stanford University Press.

Idso, C. D., Balling, R.C. (2001). An Intensive Two-Week Study of an Urban CO2 Dome. Atmospheric Research Vol. 35, No. 6, pp. 995-1000

IPCC (2001). Climate Change 2001: The Scientific Basis Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. J.T. Houghton.,Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden and D. Xiaosu (eds). Cambridge: Cambridge University Press.

Lee,Yok-shiu, “Myths of Environmental Management and the Urban Poor” in Mega-City Growth and the Future. Tokyo United Nations University, 1994.

Leitman, Josef, RapidUrban Environmental Assessment. Volume I: Methodology and Preliminary Findings.. UMP Discussion Paper 14. Washington DC: World Bank.

McGranahan, G. et. al. (2002). The Citizens at Risk: From Urban Sanitation to Sustainable Cities Earth Scan, p17.

McMichael A.J., Butler, C., and Ahern M.J. (2003) Environment as a Global Public Good for Healeh in ed. Beaglehole, R., Drager

N.and Smith, R., Global Public Goods for Health, World Health Organisation and United Nations Development Programme Collaboration, Oxford University Press.

National Strategies for Sustainable Development 2007. “World Conservation Strategy: Living Resource Conservation for Sustainable Development”. NSSD.net. Retrieved on August 2, 2007.

National Weather Service (2007). Historical data for central Arizona <www.nws.noaa.gov> (December 10, 2007)

Oke,T.R. (1982) “The energetic basis of the urban heat island.” Quarterly Journal of Royal Meteorological Society. 108, 1–24. Oke,T.R. (1987). Boundary Layer Climates 2nd edition. Routledge. London.

Oke,T.R. (1997). Urban Environments.The Surface Climates of Canada. McGill-Queen’s University Oress, Montreal, 303-327.

Parker, D.S., Barkaszi, S.F. & Sonne, J.K. (1994). Phase II:Measured Cooling Energy Savings from Reflective Roof Coatings Applied to Florida Residences, FSEC-CR-111-94, Florida Solar Energy Center, Cape Canaveral, FL..

Pielke, R.A., Avissar, R. (1990). Influence of landscape structure on local and regional climate. Landscape Ecology 4, 133-135

Price, L., Michaelis, L., Worrell, E., and Khrushch, M. (1998). Sectoral Trends and Driving Forces of Global Energy Use and Greenhouse Gas Emissions Mitigation and Adaptation Strategies for Global Change 3: 263-319

Roberts, S.,T.R. Oke, J.A Voogt, C.S.B., Grimmond, and A. Lemonsu (2003). “Energy Storage in a European City Center.” Fifth International Conference on Urban Climate, September, 2003 – geo.uni.lodz.pl.

Robertson, F.M., 1975. Hexavalent Chromium in the Groundwater in Paradise Valley, Arizona. Groundwater,Vol. 13, No. 6, pp 516-527

Robertson, F.M., 1986. Occurrence and Solubility Controls of Trace Elements in Groundwater in Alluvial Basins in Arizona. American Water Resources Association Monograph Series No. 7, pp. 69-80.

Roseland, M. (1997). Dimension of the eco-city, Cities, 14 (4), pp. 197-202.

Rosenfeld, A., H. Akbari, S. Bretz, B. Fishman, D. Kurn, D. Sailor, H.Taha (1995). “Mitigation of urban heat islands: materials, utility programs, updates.” Energy and Buildings, 22 (3), pp. 255-265.

Sailor, D.J. and Pavlova, A. (2003). Air Conditioning Market Saturation and Long Term Response of Residential Cooling Energy Demand to Climate Change. Energy – the International Journal, 28 99), 941-951.

Samules, R. (2002). Urban Heat IslandsSubmission to House of Representatives Standing Committee on Environment and Heritage Sustainable Cities 2025 Inquiry. Sydney, Australia.

Santamouris, M. (2000). Energy and Climate in the Urban Built Environment. London: James & James Ltd.

Schmidli, R. J. (1996). Climate of Phoenix, Arizona: An Abridged On-Line Version of NOAA Technical Memorandum NWS WR-

77. Weather Service Forecast Office Phoenix, Arizona. < http://geography.asu.edu/cerveny/phxwx.htm> (February 8, 2006)

Scharff, D., Burke, D.,Villeneuve, M. and L. Leigh (2002). Industrial Water Use 1996. Environmental Economics Branch, Environment Canada. Minister of Public Works and Government Services Canada. Catalogue No. En40-669/2002E.

SOS (1995). The State of the Southern Oxidants Study: Policy-Relevant Findings in Ozone Pollution Research 1984-1994 Southern Oxidants Study: Raleigh, NC, 94 pp.

Taha, H., Sailor, D., & Akbari, H. (1992). High-albedo Materials for Reducing Building cooling Energy Use. Lawrence Berkeley National Laboratory Report No. 312721 UC-350: 7

Taha, H. (1997). Modeling the Impacts of Increased Urban Vegetation on the Ozone Air Quality in the South Coast Air Basin.

AtmosphericEnvironment 30: 3423-3430

Ting, M., Koomey, J. (2001). Preliminary Evaluation of the Lifecycle Costs and Market Barriers of Reflective Pavements Lawrence Berkeley National Laboratory, LBNL-45864, Berkeley.

United NAtions (2005) Millennium Ecosystems Assessment Report. Island Press.

United Nations (2002) World Urbanization Prospects – The 2001 Revision Data Table and Highlights. Department of Economic and Social Affairs

United Nations. (1987). “Report of the World Commission on Environment and Development.” General Assembly Resolution 42/187, 11 December 1987. Retrieved: 2007-04-12

United Nations Division for Sustainable Development. Documents: Sustainable Development Issues Retrieved: 2007-05-12 US Census 2000, http://www.census.gov/population/cen2000/phc-t3/tab03.pdf

US DOE (1999). U.S. Department of Energy, Energy Information Administration, (2000). Annual steam-electric plant operation and design data.

US DOE (2000). Energy Information Administration (EIA), Electric Power Annual 1999 Volume I & II. DOE/EIA-0348(99)/1.

US EPA (1992). Cooling Our Communities – A Guidebook on tree planting and Light-Colored Structures, Socument So. 22p- 2001, US EPA, Washington DC.

US EPA (2000). The Urban Environment: Phoenix, Arizona. Environmental Protection Agency. <epa.gov/urban/phx/index.htm> Accessed August, 2007

US EPA (2001). Our Built and Natural Environments: A Technical Review of the Interactions between Land Use, Transportation, and Environmental Quality US Environmental Protection Agency. January, 200

Wackernagel, M. and Rees, W. (1996) Our Ecological Footprint: Reducing Human Impact on the Earth, New Society Publishers. BC, Canada

Wackernagel, M., Onisto, L. Linares, A.C. et. al., (1997) Ecological footprints on nations: how much nature do they use? How much nature do they have? International Council for Local Environmental Initiatives,Toronto Commissioned by the Earth Council.

Weng, W.,Taylor P.A., (2003). On modeling the 1-D atmospheric boundary layer. Boundary-Layer Meteorology 107, 371-400

WGA (2006). Clean Energy, a Strong Economy and a Healthy Environment Western Governors’ Association. Denver, CO. June, 2006

Wilson, Richard P., 1991 Summaryof Groundwater Conditions in Arizona. USGS Water-Resources Investigations Report 90-4179. Tucson

World Health Organization (1996). Climate Change and Human Health McMichael, A., et al. (eds). Geneva.

World Resources 1996-97:The urban environment. World Resources Institute, United Nations Environment Programme, United Nations Development Programme, and the World Bank.

Chapter 2:

Urban Heat Island Mitigation

Chapter 2: Urban Heat Island Mitigation

Chapter 2 Table of Contents

Introduction • 62

Land inTransition • 62

Thermal Performance of Urban Materials • 64

Urban Heat Island Mitigation Strategies • 69

Roofing • 69

COMMON ROOFING APPLICATIONS AND MATERIALS • 70

THERMAL PERFORMANCE OF CONVENTIONAL ROOFING MATERIALS                                     74 PRINCIPLES OF COOL ROOFING                                       78

COOL ROOFING TECHNOLOGIES   80 ECONOMIC BENEFITS OF COOL ROOFING          86 ROOFING ACTION PLAN   87

Pavements • 9

PAVING APPLICATIONS   92

PAVING IN THE PHOENIX REGION   95

PRINCIPLES OF COOL PAVING TECHNOLOGIES                     97 COOL PAVING MATERIALS                00

ENVIRONMENTAL AND ECONOMIC BENEFITS OF COOL PAVING                            09 PAVING ACTION PLAN                           1

Urban Forestry • 113

TREES AND VEGETATION IN THE PHOENIX REGION                                                          13 BENEFITS OF FORESTRY IN URBAN AREAS                                                             14

URBAN FORESTRY STRATEGIES     18

REFORESTATION• 118

CONSERVATION• 124

STEPS TOWARD IMPLEMENTATION     26

FURTHER INFORMATION ABOUT URBAN FORESTRY IN THE PHOENIX REGION      26

Additional Resources • 127 References • 128

2

Introduction

Phoenix and surrounding Valley cities form one of the largest metropolitan areas in the US. Population growth has increased exponentially over the last decade, forcing the expansion of urban infrastructure into areas that were once agricultural or native desert. This alteration of land cover has resulted in an average nighttime air temperature increase of nearly 8ºF (4.4ºC) over the last 50 years. (Golden 2004), This phenomenon is referred to as the Urban Heat Island (UHI) effect, and it is increasing at a dramatic rate.The Phoenix area has long been known for its pleasant winters; as the region develops, it is becoming known for its inescapably hot summer nights.

The UHI effect is the result of changes to the urban surface. As urban sprawl expands, new construction eliminates agricultural crop fields, native vegetation, and soil to make way for buildings with exposed roofing and streets with dark, dense pavement.The cooling process of evapotranspiration is lost with the removal of vegetation, and the dark engineered materials absorb and retain the sun’s intense energy during the day. Surface temperatures of these engineered materials can reach daytime temperatures of over 160ºF (71ºC) and gradually release energy stored during the day into the ambient air at night.

Increased air temperature in cities affects the amount of energy and water used in buildings and homes, changes weather patterns, increases the formation rate of smog, and affect our bodies, causing discomfort and heat related illness or even death.

This chapter of the guidebook focuses on what can be done immediately to address these problems. Affordable materials and design strategies are currently available to reshape the face of cities and reduce UHI. An overview of each mitigating strategy is presented, along with associated benefits, general costs, and suggestions for successful, citywide implementation.

Figure 2-1. The Phoenix Region, Arizona, USA.

Figure 2-2. Land-cover classifications within the Phoenix Region. (Stefanov 2001)

Land in Transition

The land cover of the Phoenix Region, as defined in Figure 2-1, has been shaped and reshaped by natural processes over millions of years. For the first time in its history, it is being reshaped by the hands of man.The materials we use to build our cities and enhance our quality of life create a unique dynamic between the energy of the sun and the urban surface.To determine the root causes of the UHI in the Phoenix Region, it is important to accurately quantify the constituents of the urban surface area A recent study conducted by researchers at Arizona State University did just that. The results, presented in Figure 2-2, indicate

Figure 2-3. Aerial view of Phoenix area, showing pavement-intensive development.

that there are several types of land cover that must be considered.

Grouping man-made surfaces together reveals that the urban surface generally consists of the following categories: pavements (parking lots, streets, sidewalks, and driveways), roofs, vegetated landscape (trees and grass), and undisturbed soil. Different cities

(a)                                                                                                           (a)

(b)                                                                                                           (b)

Figure 2-4. GIS image of (a) landscape and bare soil; (b) paved areas within Sky Harbor Airport. (Carlson 2006)

Figure 2-5. (a) Aerial image of Sky Harbor Airport and surrounding areas; (b) ASTER infrared image of same area at 10:00 p.m. on June 7, 2004. Source: National Center of Excellence, Arizona State University.

have different percentages of each type of surface material. High density metropolitan areas such as New York City and Chicago typically have more roofs than pavements and sparse vegetation within their central districts. In a lower density metropolitan area such as Phoenix, pavement comprises nearly half of the developed land cover. This is a direct result of the automobile-centric lifestyle of most Phoenicians.

In some areas, pavements comprise the majority of urban surface cover. In developments such as airports, the runways, long- term parking areas, and aircraft aprons combine to form a sea of pavement that dwarfs the building footprint. Nearly 75% of the Sky Harbor International Airport area is covered in various pavement types, as shown in Figure 2-4. This is common to airports nationwide and presents a unique challenge for airport officials. Sky Harbor International Airport is actively involved in efforts to address the UHI, with policies being implemented for pavement renovations in non-aircraft movement areas around the airport.

Figure 2-6. Average surface temperatures of six different surface materials during September 15, 2005 at Sky Harbor International Airport. (Carlson 2006)

Thermal Performance of Urban Materials

The thermal interactions within an urban environment is very complex. Surfaces made of the same material located at different areas within the same city can behave quite differently.This is a result of the microclimatic influences of the surrounding environment. Likewise, two different materials at the same location, influenced by identical conditions, can have widely different thermal behaviors. This is a function of the materials’ intrinsic properties. It is important to understand both the environmental influences and the inherent material properties of urban construction materials to discern what contributes to their surface temperatures, and in order to understand why different materials are recommended in different circumstances to mitigate the urban heat island effect.

ENVIRONMENTAL INFLUENCES

SkyViewFactor

The sky view factor (SVF) of a surface is the percentage of open sky that is in direct view from the surface (Figure 2-7). SVF ranges from 0 to 1, where 1 is a surface with hemispheric view of the sky with no interference from other structures. Some flat roofs can have an SVF near 1. Pavements, on the other hand, can have much lower SVF due to the trees, buildings, and other objects that typically surround them. SVF influences the ability of a surface to release stored thermal energy into the sky. Surfaces emit radiation to the sky both day and night. The smaller the sky view factor, the less the surface can cool through radiation

Figure 2-7. Two views from different surfaces that have similar sky view factors resulting from completely different surroundings, one an urban canopy and the other a forest. Photo courtesy of the National Center of Excellence, Arizona State University

heat transfer. Heat transfer through radiation is preferable to other means of heat transfer in UHI mitigation because radiation will generally not heat the air above the surface as much as convection and conduction heat transfer will. Air does not readily absorb long wave radiation (thermal radiation), and therefore a large percentage of heat leaving a surface in the form of thermal radiation will pass through ground level air and dissipates through the upper layers of the atmosphere

Solar Access

The solar access of a surface describes the time and duration that a surface is directly affected by solar energy. This value varies

Figure 2-8. A computer generated shadow analysis of downtown Seattle, WA., showing different surfaces have more exposure over the course of the day. (a) June, 9:00am; (b) June, 12:00pm; (c) June, 3:00pm; (d) June, 6:00pm. Source: Seattle Municipal Civic Master Plan (1999).

by season and time of day. Surfaces that are surrounded by tall buildings may only receive direct solar radiation for a few hours at midday during the summer, and not at all during other times of the year.This can be determined with a shading analysis tool as shown in Figure 2-8.

Wind

As cool air moves over a surface, it picks up thermal energy and thereby reduces the temperature of the surface. Wind direction and speed results from differences in air pressure caused by temperature differentials and geometries within urban areas. Wind can also be created by man-made equipment such as passing automobiles, airplanes, or ventilation exhaust units. Wind dispersion is one of the most important and complex elements of UHI analyses. Surfaces located in narrow building canyons can be sheltered from strong seasonal winds, while at other times, the wind speeds can be intensified, depending upon the direction of prevailing winds. Surface temperatures of pavements are greatly influenced by the speed and frequency of traffic driving across them. It is common that the surface temperatures of highway shoulders (no traffic) far exceed the temperatures of center lanes with high traffic volumes.

Moisture

The amount of moisture within, below, and above urban surfaces can greatly affect their thermal behavior. As water is heated by solar energy from a liquid to a vapor, it is then pulled away by passing air currents, taking heat energy with it and cooling the surface. This phenomenon, evaporation, is how vegetation and the human body keep cool. Moisture content within soils and pavement surfaces greatly alters their thermal transport properties making modeling these properties more complex in moist conditions

Humidity

The relative humidity of ambient air can have a significant effect on evaporation rates at the surface of plants, soils, and even human skin. Generally, evaporative cooling methods are most effective in drier climates. This is why different cooling strategies must be evaluated appropriately in different regions of the country; something that works well in Phoenix may not be ideal for the humid climate of New Orleans

THERMOPHYSICAL PROPERTIES

Analyzing the thermal behavior of urban materials may be more understandable with a brief description of the thermophysical properties of matter. There are two distinct categories of these properties: those related to transport of energy through a

Figure 2-9. The effect of different thermal properties on the maximum and minimum

temperatures of surfaces. A negative temperature gradient correlates to a decrease in temperature.

Source: (Gui el. al. 2006).

system, and those related to the thermodynamic, or equilibrium state, of a system (Incropera and DeWitt 1996).

Transport of energy through a system, also referred to as heat transfer, occurs in three ways: radiation, conduction, and convection.Transport properties relating to radiation heat transfer such as albedo and emissivity will be discussed in more detail below, along with the rate coefficients that govern conduction and convection heat transfer.

Thermodynamic properties differ from transport properties in that they are concerned with the equilibrium state of a system These properties include density and specific heat, which are the basis of volumetric heat capacity and thermal diffusivity.These properties and terms are discussed in detail below (Figure 2-9)

Albedo

Albedo is the term given to the amount of solar energy that is reflected by a surface. The higher the albedo of a surface, the less solar energy it will absorb. Albedo is the first line of defense a surface has against incoming solar radiation. It is regarded as the most important factor in the mitigation of the urban heat island effect in urban centers (Rosenfeld et al. 1995). The value of albedo can range from 0 (perfect absorber) to 1 (perfect reflector). Albedo is the ratio of solar radiation that reflects off of a surface divided by the total incoming radiation. For this reason, albedo is also given as a percentage (e.g., an albedo of 0.75 indicates that 75% of the solar radiation that hits the surface is reflected). Very often, high albedo is related to lighter shades of color but a more complex analysis is required to determine the true albedo of a given surface. Because solar energy is comprised of 10% ultraviolet, 40% visible, and 50% infrared wavelengths, a large portion of the solar energy cannot be seen. Color, to the naked eye, is only the visible energy that is reflected by a surface.To accurately determine albedo, one must use a sensor that also detects light in the infrared region. Error! Reference source not found. Figure 2-10 and Figure 2-11 show typical albedo ranges for common urban surfaces

Figure 2-10. A typical urban area, with roof and wall albedo ranges indicated on the different surfaces.

Source: National Center of Excellence, Arizona State University

Figure 2-11. A typical urban area showing various ground- level-material albedo ranges.

Source: National Center of Excellence, Arizona State University.

Emittance

A portion of the thermal energy contained within any surface is constantly being emitted as radiation back into the atmosphere The property that indicates a surface’s ability to emit radiation is referred to as its thermal emittance, which can range in value from 0 (non-emitter) to 1 (perfect emitter). Most natural and construction materials have relatively high emittance values, as shown in Figure 2-12.

The infrared emittance of a surface greatly depends on the surface material and its finish. For instance, a polished copper surface will have a very low emittance level close to 0.06, while rough surfaces such as concrete and asphalt have an emittance level above 0.90

Convection Coefficient

Convection heat transfer describes energy transfer due to random molecular motion (conduction) and bulk fluid motion (Incropera and DeWitt 1996). This kind of heat transfer occurs between a surface and the ambient air that passes over it. The proportionality constant, convective heat-transfer coefficient, is dependant on surface characteristics and environmental conditions, including surface roughness, air velocity (wind), and the type of fluid motion (turbulent vs. laminar) of the air above the surface. Therefore, the convection coefficient assigned to a specific material depends on these conditions. However, it is possible to gauge which surfaces will be more efficient at transferring heat through convection due to certain characteristics (such as surface porosity) that increase the surface area and mixing of air over the surface.

Density

Density is widely used in thermal analysis. It is the measure of mass per volume of a substance. Generally, materials with higher density will transfer and store more solar energy than lower density materials.

Specific Heat

Specific heat is also used in determining the thermal behavior of surface materials. It is typically defined as the amount of heat energy required to raise the temperature of one gram of a substance by 1.8ºC. It is not useful for comparative purposes until it is combined with density to form the volumetric heat capacity.

Volumetric Heat Capacity

When the density and specific heat of a substance are multiplied together, they equal the volumetric heat capacity of the substance (Incropera and DeWitt 1996b). The volumetric heat capacity quantifies the ability of a material to store thermal energy

Thermal Diffusivity

The ratio of thermal conductivity to the volumetric heat capacity is an important factor in heat transfer analysis.This property, termed thermal diffusivity, measures the ability of a material to conduct heat relative to its ability to store heat energy. The

thermal diffusivity enables one to estimate how a material will behave under certain conditions. For instance, a material having a very large diffusivity will respond more quickly to thermal changes than a material of small diffusivity. The smaller the thermal diffusivity the longer it will take to reach an equilibrium tate

Porosity

The porosity of a material is defined as the ratio of the volume of pores in a substance to its total volume (Somayaji 2001).This term is widely used when discussing groundwater transport through soils. The same concept can be applied to porous pavements, which are becoming more common in various applications including innovative storm water management in parking lots and sidewalks. Porosity is an important design consideration when permeability is desired.

Figure 2-12. A visual representation of the magnitudes of absorptivity and emissivity for common building materials. Source: Lawrence Berkeley National Laboratory.

Permeability

Permeability is commonly defined as the ability of a surface material to allow fluids such as rainwater to move through it.The majority of conventional pavement designs undergo compaction during construction to significantly limit the transport of water through them.The more porous a pavement is, generally, the more permeable it is.

Permeability is also an important factor when considering surface energy fluxes. Permeable areas such as exposed soil and grass landscaping are often cooler during the day because of their ability to transform incident solar radiation into latent heat (Taha 1997). Latent heat is the energy that drives evaporation at the surface of leaves and moist soils. Latent heat does not raise the temperature of the fluid but is responsible for the phase transition from liquid to a vapor. Non-permeable and dry pavements lack this ability, thereby increasing the thermal energy that becomes stored in the material.

UHI Mitigation Strategies

Urban-heat-island mitigation strategies can be grouped into three categories:

• Roofs
• Paving
• Urban Forestry

As mentioned previously, pavements and building roofs form more than half of the urban surface in the Phoenix metropolitan area. By providing cool alternatives for these two surface material categories, decision makers can have a significant effect on their communities.Trees are also an important asset in mitigating adverse urban air temperatures. While trees are not usually thought of as a technology, it is important that cities assess their tree populations, or lack thereof. The following three sections will delve into each of these key mitigation strategies and provide lists of commercially available and affordable alternatives to conventional materials and designs.

ROOFING

Buildings make up a significant portion of land cover, and cooling their interiors is often the greatest source of energy demand in an urban area. In the US, over one-sixth of the total electricity consumed is for air conditioning alone. Nearly 15% of Phoenix’s land cover is comprised of buildings, from flat roofs of multi-story skyscrapers in the central business district to the pitched roofs of residential neighborhoods (Bhardwaj 2006).The surfaces of traditional roof systems using modified bitumen and dark asphalt shingles can reach temperatures of 150ºF (65.5ºC) to 180ºF (82ºC) during the sweltering Arizona summers. These extreme temperatures can have major economic and environmental impacts on a metropolitan area

The large temperature swings that these roofing materials undergo can cause premature aging, resulting in cracking and curling that require regular maintenance or replacement. In addition, their elevated temperatures affect the solar heat gain of the interior itself, forcing the mechanical cooling equipment to run longer to maintain a comfortable indoor environment. Finally, the elevated surfaces transfer heat to the air passing over the roof, thereby contributing to the urban-heat island effect.

The good news is that these elevated roof temperatures can be reduced dramatically using readily available and extensively proven roofing alternatives.These roof systems, referred to here as cool roofs, can cut peak summer roof temperatures by 60ºF (33ºC), will have longer operational lifetimes than conventional roofs, and can result in huge energy savings for building owners. This section of the guidebook will focus on different cool roofing technologies that are currently available and in use around the country. We begin by defining and quantifying the different types of buildings and roof types in Phoenix and other major urban areas. This is followed by a review of the various cool roofing solutions, along with relative costs, applications, material properties, and benefits. Finally, suggestions for implementing cool roofing in existing and future building construction and retrofits in the Phoenix region are provided.

Figure 2-13. Roofing in Phoenix, Arizona. Photo courtesy of National Center of Excellence, Arizona State University.

Roofing in the Valley of the Sun

Phoenix and its surrounding communities are similar in design to other modern metropolitan areas built after the advent of the automobile, with a relatively small urban core surrounded by an expansive area of low-rise (one or two-story) buildings (see Figure 2-13). Buildings of similar design and function can be grouped and categorized as either residential, commercial, office, industrial, or public buildings. While nearly 15% of Phoenix’s total land area is covered by buildings, this percentage can vary greatly by neighborhood and is changing rapidly as local cities expand and ‘infill’ of new buildings in older areas is done. Surface classification of Houston, Texas, revealed that nearly 50% of its building surface areas were residential. In this study, we assumed the same percentage applies to Phoenix due to the large number of single-family homes built in the Valley over the last 10 years. The US Census Bureau recorded 11,403 new permits for single-family homes (out of 11,836 total residential building permits) in Maricopa County in 2006 alone.This equates to 2.14 billion in total construction dollars in the Valley each year.

CommonRoofing Applications and Materials

Roof designs can be described as steep or low sloped depending upon the pitch of the roof. Steep slope indicates an elevation change of more than four inches per foot; low slope roofs are those with less pitch. Zero slope or flat roofs fall under the low slope category. In 2001 the National Roofing Contractors Association’s (NRCA) Annual Market Survey showed that 63% of all roofing in the U.S. was low slope, as shown in Figure 2-14. Of the low sloped roofs installed, 62% involved re-roofing, with 25%

Figure 2-14. Roofing sales in the United States by type, and breakdown of all low- slope roofing activities in 2001. Source: NRCA (2002).

and 15% for new construction and maintenance, respectively. With the rapid housing development in Phoenix in the last five years, it is expected that new construction may have a larger percentage of the market than these national figures present. Re- roofing and new roof construction projects are perfect opportunities to apply energy efficient roofing materials and designs.

Many products are available for low slope roofs. Roofing materials used for single family residential buildings historically have consisted of asphalt shingles, but recent trends in Arizona favor concrete tiles as shown in Figure 2-15.

These results are from the NRCA’s 2004 survey of the roof construction field. Figure 2-17 indicates that steep slope buildings use predominately architectural metal or fiberglass asphalt shingles. A brief description of each of these common roofing materials and information on their thermal performance are provided on the following page.

Figure 2-15. Concrete-tiled roofs in the Valley of the Sun. Photos courtesy of National Center of Excellence, Arizona State University.

Figure 2-16. Percent of new construction and reroofing by material type in the US for low-slope roofs 2004. *Built- up membranes using modified bitumen cap sheets are considered modified-bitumen roof systems.

Source: NRCA (2005).

Figure 2-17. Percent new construction and reproofing by material type in the US for steep-slope roofs in 2004.

*Built-up membranes using modified bitumen cap sheets are considered modified-bitumen roof systems.

Data Source: NRCA (2005).

Asphalt Shingles

Asphalt shingles are the most popular type of residential roof material in consideration of cost (as low as $0.80 per square foot installed), ease of installation and the availability of a wide range of colors (Figure 2-18). There are two types of asphalt shingles – glass fiber and organic. Organic shingles consist of paper saturated with asphalt and coated with adhesive asphalt in which ceramic granules are embedded. Organic shingles are heavier and more durable than glass fiber shingles due to 40% more asphalt content.

Glass fiber shingles are reinforced with a glass fiber mat, which is coated with asphalt and mineral fillers to create a waterproof barrier. Ceramic granules are embedded into adhesive asphalt on one side of the mat. The roofing granules are typically 1 mm diameter grains of crushed granite, coated with an inorganic silicate material.The coatings help to give the granules their desired color

The granules of both type of shingles provide the color and give protection from the sun’s ultra violet (UV) rays, otherwise the asphalt would deteriorate very quickly. Glass fiber shingles are by far the most common roof material in the U.S.The average lifespan of asphalt shingles depends upon the climate. In Phoenix, for example, asphalt shingles rated for 20 years may actually last less than 14 fourteen years because of the intense summer sun (Figure 2-18).

Figure 2-18. Common asphalt shingles up close. Photo courtesy of National Center of Excellence, Arizona State University.

EPDM

Ethylene Propylene Diene Monomer (EPDM) is a terpolymer product, consisting of three distinct monomers. EPDM is a single-ply (layered) thermoset (heat cured) material. Thermosetting can occur at the manufacturing plant (vulcanization) and delivered in rolls, or the material can come unvulcanized in a bucket and be applied to the roof, with the natural weather conditions finishing the curing process (Figure 2-19 and Figure 2-20).

EPDM membranes range from 0.030-inch (0.8-mm) thick to 0.100-in (2.5-mm) thick, and have been used in the US since the 960’s. EPDM is cheaper, easier to install, and less messy than older roofing methods. The sheets can be fastened to the roof using water or solvent-based adhesives, either using mechanical fasteners or loose-laid. Sheets are then covered with a ballast of round river rock (application weight 1,000-12,000 pounds per 100 sq ft) or concrete pavers (20 lbs per sq ft).

Figure 2-19. A fully adhered EPDM roof surface. Source: Kozlowski Co. (http://www.kozlowskico.com/)

Figure 2-20. Image of a ballasted, loose EPDM roof. Source: NRCA

Figure 2-21. Modified bitumen on commercial, low-slope buildings.Photos courtesy of National Center of Excellence, Arizona State University.

Figure 2-22. (a) Example of a modified-bitumen roll.;

(b) Application of modified bitumen roll. Source: www.derbigumus.com.

Modified Bitumen

Modified Bitumen (MB) uses asphalt with specific modifiers mixed in to give it plastic or rubber-like properties. Common modifiers include atactic polypropylene (APP) and styrene butadiene styrene (SBS). MB comes in meter wide rolls. Once the rolls are placed, a torch or hot bitumen is used to rapidly heat the material to bond it to the surface. Following the melting and adhesion process, the BM sheets are typically covered with mineral granules such as aluminum, copper, or an aggregate such as gravel or slag to protect them from UV degradation. Figure 2-21, and Figure 2-22 illustrate different MB roofs.

Built-Up Roof (BUR)

Built-up roof (BUR) is one of the oldest and most reliable roofing methods, dating back to the 1840s. BUR is comprised of layers of roof felts laminated together with a waterproofing bitumen such as asphalt, coal tar, or lap cement. The layers can be made of any combination of saturated felt, coated felt, polyester felt, or like fabrics. The top layer is usually covered by asphalt, some type of aggregate, emulsion, or granule surfaced cap sheet. The service life of BUR can vary greatly due to factors like climate, foot traffic, materials used, construction quality, and roof slope. Under ideal conditions, a three ply BUR can last 15 years and a five ply may last 25 years.

Architectural Metal

Metal roofing has become increasing popular over the last decade due to its long life, relatively light weight, recyclability, and variety of forms and colors. Most metal roofs are made of steel. Stainless steel, aluminum, copper, and zinc alloys can also be used, but are very expensive. A steel roof is typically protected from rusting or corrosion with a zinc coating or epoxy primer and then a baked-on acrylic. Highly durable paints and its extensive formability enable metal roofing to resemble many other kinds of roofing materials, such as shingles and clay tiles. Metal systems are best suited and most popular for steep sloped roofs of residential and commercial buildings because of their aesthetic appeal and low maintenance. Properly constructed metal roofing systems are rated to last for over fifty years before full replacement is required.

Figure 2-23. Metal panels on a steep-slope commercial structure can have high surface temperatures during the day. Photos courtesy of National Center of Excellence, Arizona State University.

Thermal Performance of Conventional Roofing Materials

To better understand the thermal performance of the materials that are commonly being used on roofs in Arizona and nationally, researchers at the Oakridge and Lawrence Berkeley National Laboratories conducted extensive research into the properties of common roofing materials as part of a decade-long project for the U.S. Department of Energy and the U.S. Environmental Protection Agency.They summarized their findings and presented average values for the following four categories:

1)  Solar Reflectance – the fraction of incident solar energy that is reflected by a surface.The values were measured in accordance with ASTM Standards E903 and E892 using a spectrophotometer.

2)  Infrared Emittance – a surface property ranging from 0 to 1 that indicates the ability of a hot material to shed heat in the form of radiation

3) Temperature Rise – the maximum roof temperature rise above ambient air temperature is calculated using the equation on the following page.

(1-R)I0-h(T ir – Tsky)

T               h +h

Where..

R = albedo (reflectance)

I = solar flux = 1kW per square meter of roof (assumed)

h= heattransfer coefficientfor radiative cooling = 6.1Wm ºC ^–

Where    = thermal emittance of the surface Tair = ambient air temperature

Tsky = sky temperature, assumed to be 10ºC lower than ambient So,Tair – Tsky = 10ºC

h = convection heat transfer coefficient = 12.4 Wm ºC (assumed) (Berdahl 2000)

Figure 2-24. Temperature response of roofs, pavements, and walls during an average summer day in Phoenix. Photos courtesy of National Center of Excellence, Arizona State University

4)  Solar Reflective Index (SRI) – a measure of the surface’s ability to reflect solar heat. Each material is compared to a standard black (albedo 0.05, emittance 0.90) which represents an SRI = 0, and where a standard white (albedo 0.80, emittance 0.90) is equivalent to SRI = 100. It is calculated that a standard black will have a temperature rise of 90ºF (50ºC) in full sun, while under the same conditions, standard white has a temperature rise of only 14.6ºF (8ºC).The maximum calculated surface temperature is then used to estimate the SRI as interpolated between black and white. Using this procedure for estimating SRI, some very hot materials will have negative SRI values and ultra-cool materials will have SRIs greater than 100.

According to research conducted at Lawrence Berkeley’s National Lab (LBNL), the solar reflectance of commercial asphalt shingles is very low (i.e. absorbs heat). Table 2-1 shows that even the premium white shingles only reflect about 30% of sun’s energy. Paul Berdahl, the author of the LBNL study, believes that the low reflectance is the result of several factors including the limited pigment applied to the granules. It is also believed that the roughness of the shingle surface increases the solar absorption as light does not reflect uniformly when striking a non-planar surface. In the case of some of these products, a large portion of the black asphalt is still exposed and absorbs nearly 95% of the incident energy. All of these factors cause the surface of asphalt shingles to heat up to temperatures that are over 60ºF (33ºC) warmer than the ambient air (i.e. low SRI).

Table 2-1. Solar reflectance and thermal performance of asphalt shingles. SOurce: LBNL, 2000.

Table 2-2. General Solar performance characteristics of Roofing Membranes. Source: LBNL, 2000

The thermal performance of several types of common roof membranes is provided in Table 2-2. including single ply materials EPDM and Modified Bitumen and the multiple ply Built Up Roof systems.The solar reflectance of these surfaces depends on the type and color of the base polymer and the granule materials applied to the top surface. It is clear that the surface using bitumen based materials performed the worst due to the dark color of the material.T-EPDE performed the best, primarily because of the bright white color of the rubber membrane.

Metal roofs made from galvanized steel, aluminum, or copper usually have good reflectance properties; however, they can reach high daytime temperatures due to their low emittance. This problem is often mitigated by applying thin polymer coatings over the surface during manufacturing.Table 2-3 provides examples of typical values for bare galvanized steel, aluminum, and two metal surfaces that have been treated with white polymer coatings.

Table 2-3. Solar reflectance and thermal performance of metal roofing. Source: LBNL, 2000

A wide variety of roofing tile colors are being used in new developments in the southwestern US. Many of the more popular styles mimic the deep oranges and reds of the clay tiles found in Spain and Italy.

Table 2-4 shows that even though these tiles can be highly emissive, their limited reflectivity results in peak temperatures of 60 to 70ºF above that of ambient air.

Table 2-4. Solar reflectance characteristics of roof tiles. Source: LBNL, 2000

Figure 2-25. Spectral characteristics of common building materials. Source: Florida Solar Energy Center

Principles of Cool Roofing

Figure 2-26. Surface temperatures and corresponding albedos of different roofing materials. Source: Lawrence Berkeley National Lab

Cool roofs to maximize one or more of the following basic principles (Figure 2-29):

1)   REFLECT as much solar energy as possible.The less energy that penetrates the surface, the lower the surface temperature will be.

Figure 2-27. Principles of cool roofs and walls. Illustration: J. Carlson, National Center of Excellence, Arizona State University (2007).

2)   EMIT absorbed energy as quickly as possible.The closer the thermal emittance is to 1, the better the surface will release heat. Because air is virtually transparent to long wave radiation, energy emitted into the night sky in the form of radiation will not be transferred to the ambient air above the surface.This can have a positive influence on the urban heat island effect

3)   EVAPORATE moisture to cool the air and roof surfaces. Evapotranspiration at the surface of vegetation, soil, and water bodies converts incident solar radiation energy from the sun into latent heat as it transforms from a liquid to a vapor.

Question:What determines whether a roof is a ‘cool roof ’ or not?

There are several public and government entities that have asked this question. They established the following criteria for what constitutes a ‘cool roof:

EPA’s Energy Star® program has established an initial albedo for low-slope roofing

of 0.65, for steep slope roofing of 0.25, and an aged (three-year) albedo for low slope roofing of 0.50 and steep-slope roofing of 0.15.

Website: http://www.energystar.gov/index.cfm?c=roof_prods.pr_roof_product

Figure 2-28. Energy Star® Logo

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) have included specifications for cool roofs into the standard ASHRAE 90.1- 2004 They have established an albedo of 0.70 and emittance of 0.75.

Website: http://www.ashrae.org/

GeorgiaWhite Roof Legislation: The Georgia White Roof Amendment has adopted the criteria established by ASHRAE 90.1. Cool Communities program in Atlanta.

Website: http://www.coolcommunities.org

California’s Cool Roof Program: The State of California has developed a Cool Roofs Program with established criteria of Initial Solar Reflectance and Emittance for low slope roofing of 0.65 or greater and 0.80 or greater, respectively; or a Minimum SRI of 75 using ASTM1980. Steep roof criteria to meet EPA Energy Star and high profiled tiles are to have initial albedo of 0.40 or greater and emittance of 0.80 or greater, or an SRI 41 using ASTM 1980. Web site: http://www.consumerenergycenter.org/coolroof

LEED® Program: U.S. Green Building Council’s Leadership in Energy & Environmental Design (LEED) program offers credits in the category of “Sustainable Site/Urban Heat Island Effect.” One credit is achievable if the building uses a roof with both high solar reflectance and high emissivity.The requirement states: “Use Energy Star Roof compliant, high reflectance and high emissivity roofing (initial albedo of at least 0.65, three year aged albedo of at least 0.50 when tested in accordance with ASTM E 903, and emittance of at least 0.90 when tested in accordance with ASTM E 408) for a minimum of 75% of the roof surface; OR, install a green roof for at least 50% of the roof area.”

Web site: http://www.usgbc.org/LEED/LEED_main.asp

Question:How is the reflectivity and emittance of a roof or product measured?

There are standardized test methods for determining the solar reflectance and emittance of a product in the field or laboratory. The test methods are available from the American Standard for Testing and Materials (ASTM). The test methods for solar reflectance are ASTM E 903, ASTM E 1175, and ASTM E 1918.To get a rough measurement of reflectivity of large surfaces in the field, the standard ASTM 1918 can be used. Thermal emissivity is measured using ASTM E 408, ASTM C 835, and ASTM C 1371. Calculating solar reflectance index (SRI) is described in ASTM 1980.

Question:How can I be sure that a roofing product will meet the cool roof requirements without measuring it?

The Cool Roof Rating Council (CRRC) is an independent and unbiased organization that has developed protocols and procedures for testing products for Solar Reflectance and Emittance. Any product that has gone through the structured and rigorous testing requirements defined by the CRRC will have the CRRC label (see Figure 2-29) on the product packaging.The CRRC label alone may not indicate that the product is a ‘cool roofing’ product.The EnergyStar® label verifies that the radiative properties measured by the CRRC for this product meet the cool roofing requirements as defined by the EnergyStar® requirements. The CRRC also serves as a library for data from tests performed by CRRC-accredited laboratories on the wide range of materials submitted by manufacturers. Find out more at http://coolroofs.org.

Figure 2-29. The Cool Roof Rating Council Label.

Cool Roofing Technologies

Cool roofing products have been used to reduce energy consumption for several decades, and new products are being developed all the time. The products that have been most successful are those that easily adapt to use with the most common roof types. Other, less conventional products may be even more effective, but due to lack of contractor experience, higher initial cost, and lower availability, they have not been as rapidly adopted by the roofing industry. There are five categories of cool roofing technologies for use in both new construction and re-roofing applications. This section describes each technology and explains when it is best used, what’s ‘cool’ about it, and its cost compared to other roofing materials.

Cool Liquid-Applied Coatings

Liquid coatings are the most versatile cool roof technology as they can be applied to the top surface of the roof covering or membrane of either new or existing roofs. Titanium dioxide and zinc oxide are mixed into acrylic polymer to create durable, bright white coatings, and this pure white coating can achieve initial reflectance values of 75-80% and emittance of 0.90. For those not desiring a bright white look, other colored pigments can be added, but any additional color will result in a decrease in reflectivity depending on the hue. These coatings generally have a thickness of 15-20 mils (mil = 0.001 in), and can be applied to almost any roof surface regardless of slope and material – built-up roofs, spray applied polyurethane foam, modified bitumen, or metal. Figure 2-30 below compares the maximum surface temperature of a low slope roof before and after treatment with a commercially available cool roofing coating product.These liquid applied coatings offer affordability and ease of application for improving the performance of existing roof materials, and there are a wide variety commercially available. Check for the Energy Star® Certified Labe when looking for products that meet the minimum Solar Reflective Index values.

Figure 2-30. Cool roofing on a commercial low sloped roof.The surface temperature was reduced by 85ºF after the roof was treated with a liquid applied cool roofing product. Images courtesy of Hydro-Stop, Inc.

Figure2-31.Liquid-applied cool-roof

coating (product Mirror SealTM) on a low-slope, residential roof in Guadalupe, Arizona. Photo courtesy of National Center of Excellence, Arizona State University.

Figure 2-32. Walls also present an opportunity to use reflective coatings.This example shows how a simple layer of reflective paint (represented by a dark purple) can dramatically affect the surface temperature of a brick wall. Photos courtesy of National Center of Excellence, Arizona State University.

New liquid applied cool wall coatings are also becoming available from large paint manufacturers.The paints come in a variety of colors while still reflecting infrared radiation.The temperature of a wall can be greatly reduced with the simple application of a reflective coating.

Cool Prefabricated Membranes

Many of the single ply membrane materials already in use, such as Ethylene Propylene Diene Monomer Rubber (EPDM) Polyvinyl Chloride (PVC), Copolymer Alloys and Thermoplastic PolyOlefin (TPO), are naturally white and opaque. These membranes are typically over 45 mil thick and can be rolled out and attached to roofs, providing an initial reflectance of 0.75 to 0.85 and an infrared emittance of 0.80. With any highly reflective surface, it is vital that the roof be adequately sloped to drain precipitation and remove dust from the surfaces during rain events.

Other, darker membranes, such as modified bitumen and prefabricated asphalt rubber sheets, can be made more reflective by adding other materials to the surface during manufacture. Generally, metallic foils, mineral granules, and other proprietary materials can be embedded on the top surface to achieve improved reflectivity. While there is a limit to the effectiveness of coated mineral granules, typically only achieving reflectance of 25%, a metallic foil-embedded fabric can improve reflectance values to 85%, and a white coating applied to the flakes can achieve an emittance of 0.80.

Figure 2-33. Cool-roof, PVC, single-ply membrane applied to a roof.Photo courtesy of Honolulu Roofing Company.

Cool Metal Panel Roof Systems

Metal roofs are prefabricated, allowing for reflective, high-emittance treatments to be added during the manufacturing process. The metal sheets can be formed and installed in a variety of configurations depending upon the desired style and slope of the roof. Special reflective coatings are usually baked on to ensure surface durability. Innovations in the metal treatment process have developed colored surface treatments that reflect more energy in the invisible near-infrared range than in the visible spectrum This results in a colored metal roofing system that stays cooler than conventional surfaces of the same color. These reflective panels can achieve solar reflectance of 0.15 to 0.70. The additional benefit of using steel is that it can last over fifty years, costs nearly the same as tile, is less messy than liquid applied roofing products, and is 98% recyclable after deconstruction.

Figure 2-34. A cool metal roof. Photo courtesy of the BASF Company

Emerging Products for Tiles and Shingles

New products are continually emerging in the cool roof industry. Most of these products are suitable for steep slope roof applications. Concrete and clay tile products, coated or tinted with light colored pigments with reflectance values greater than 0.40, are among these new products (Figure 2-35). While asphalt shingles are still the dominant roofing material for steep sloped residential construction, new metallic coated shingles are starting to become more available. The limited use of these products for steep sloped residential roofs is a result of several factors: limited awareness of homeowners, lack of government incentives, and, until recently, the lack of a LEED Certification for Homes, all resulting in limited demand. This trend is likely to change as homeowners become more aware of climate change and energy use.

Figure 2-35. Reflective roof tiles.Source Sacramento Bee, Sacramento, California

Vegetated/Green/Brown Roof Systems

Vegetated roof systems, also referred to as green roofs, date back to ancient times. The combined cooling effect of evapotranspiration, the insulating ability of earthen materials, and the aesthetic appeal make vegetated roof systems an increasingly popular solution for managing storm water and mitigating UHI effects in densely built urban areas. The term “brown roofs” applies to vegetated roof systems in arid climates where vegetation is quite different in appearance from the lusher foliage found on green roofs in wetter areas such as the Midwest or Northwestern U.S.

A typical vegetated roof includes the following components (starting from the structural roof surface and moving upward):

Waterproofing/roofing membrane – made of any one of the roof membranes discussed above (liquid applied, polymeric rubber; hot applied, rubberized asphalt; prefabricated, single ply membrane; or multiple ply, modified bitumen membrane)

Insulation medium– typically an extruded, polystyrene insulation

Supporting structure – metal structure to support the load of growing medium, vegetation, and sometimes foot traffic

Waterproofing membrane – to prevent water from reaching the roof after passing through the growing medium

Drainage medium – a prefabricated, polymeric drainage panel or gravel fill material

Filtration medium – this could be any combination of root-barrier geotextiles, drainage mats, aeration products, and water retention mediums

Growing medium – may be traditional planting soil or engineered lightweight growing mediums.

Vegetation – grasses, shrubs, cacti, bushes, or even trees, depending upon whether the roof is an intensive or extensive system

Figure 2-36. Cross- section of green roof assembly.

Source: US EPA

Extensive vs. Intensive Green Roof Systems

When designing a green roof it is important to consider climate conditions, level of maintenance required, and water availability. Roofs that employ durable, self-propagating, and small native plants can often be constructed with thin growing medium layers (4-6”), which after the initial growing stage can thrive on the rainfall in the area. These designs are referred to extensive greens roofs, and typically require less maintenance and structural support due to the reduced water needs and weight of the growing medium.

Figure 2-37. Modular, extensive green roof being constructed on a sloped residential home in Pinon, Arizona. Source: www.greenroofs.com.

Figure 2-38. Example of plant types used in extensive green roofs. Photo courtesy of National Center of Excellence, Arizona State University.

Intensive green roofs are quite different.These systems require at least twice the growing medium layer depth (6-12” depth), constant pruning and watering, and are only suitable for low sloped roofs. However, intensive green roofs can support a greater diversity of plants, offer more shade for roof visitors, and provide valuable habitat for nesting birds and other urban wildlife. Most intensive green roofs are designed to simulate parks and encourage visitor interaction and enjoyment. In some cases, intensive green roofs can function as urban farms, growing edible plants for the pleasure and consumption of building occupants.

Figure 2-39. An intensive green roof on Chicago’s City Hall.The infrared image on the right shows the dramatic temperature difference between a normal built-up roof and a green roof under identical conditions. The air temperature was around 85oF. Photos courtesy of National Center of Excellence at Arizona State University and Department of the Environment, City of Chicago

Vegetated roofs have additional benefits beyond reducing the surface and air temperature around buildings. They can also improve water quality and reduce the rate of stormwater runoff, thereby limiting the risks of flooding around a building perimeter. The growing medium and filtration in vegetated roof system captures and filters the rainwater before releasing the unneeded portion to either irrigation storage tanks or to the surface below. A four inch deep green roof can retain as much as an inch of rainfall before it begins to release unused rainwater through the drainage medium. During this process, pollutants are broken down by microorganisms in the soil and heavy metals are retained.The rainwater passing through the layered system slows the discharge, which can prevent sudden surges into ground level retention areas, allowing infiltration to occur slowly and preventing overflow and flooding.

In addition to these environmental benefits, green roofs are considered attractive areas where people can enjoy interaction with vegetation. Green roofs can be designed with walking and sitting areas and can improve the marketability of a property. Studies have also shown that the color, sound, and appearance of vegetation and wildlife can reduce stress and improve worker productivity. These benefits can be realized when building occupants view a green roof from a location above or at the same evel as the roof

Figure 2-39. Plot of cumulative runoff over time using various types of roofing materials. Source: Whole Building Design Guide, www.wbdg.org.

Comparing Cool Roof Options

is a complete analysis of comparing the application, attributes, costs, and typical lifespan of many cool roofing product options.

Table 2-5. Comparison of cool roofing options.

Economic Benefits of Cool Roofing

The ability of cool roofs to reduce urban temperatures is clear, but building owners may need more incentive to implement these technologies. Cool roofs will actually pay for themselves over a relatively short period of time. Cool roofing retrofits are proven to benefit building owners directly through energy savings and reduced maintenance costs. This section takes a closer look at the benefits in detail and shows that cool roofing makes economic and environmental sense for building owners, tenants, and the community as a whole.

Energy Savings and Peak Demand

Heat transfer through the roof of a building can increase the air temperature inside, resulting in an increased demand for cooling. Electrical energy demand for cooling makes up 11% of the total electricity consumed in the United States, and this percentage is even greater in hot, arid climates such as Phoenix. Research studies of individual buildings equipped with sensor networks were monitored before and after implementing cool roofing technologies. These studies produced by Lawrence Berkeley National Laboratory, the Florida Solar Energy Center, and others, showed energy savings of 20-30% when cool roofs were implemented. In terms of air temperature around a building, a decrease of 3-7ºF can lead to a 10% reduction in air conditioning requirements. A study in Houston, Texas showed that cool roofing technologies, if implemented on just office and retail buildings, could result in $9-18 million savings annually (Konopacki and Akbari, 2002). An even greater energy savings could be realized by the Phoenix region if cool roofing technologies were implemented in similar facilities. To learn more about how much energy can be saved for a particular building, go to EnergyStar®’s cool roof energy savings calculator at: http://roofcalc.cadmusdev.com/default.aspx.

This calculator uses the general design and location of a building to compare potential energy savings using different types of conventional and cool roofing technologies.

Peak energy demand in the Phoenix region occurs during the hottest part of summer days.This is when cool roofing could be most beneficial. By maintaining roof temperatures closer to ambient air conditions, energy use within the individual building is reduced.This reduction in cooling requirements can help reduce regional peak energy demand during the afternoon. Replicating this energy reduction over the entire Phoenix area would add up to huge savings for the City as energy is charged at the premium rate during peak hours. Cool roof strategies result in savings for the building owner, but also reduce the need for additional energy generation facilities to increase capacity, reducing air quality impacts, and save tax payers money.

Occupant Comfort

Cool roofs can limit the temperature swings within buildings that cause discomfort for occupants. Many facilities such as warehouses, storage areas, and older buildings have limited air conditioning and/or insulation. Cool roofing technologies can have their greatest effect on these types of buildings and improve the productivity of workers.

In addition to increasing comfort inside a building, reduced roof temperatures can reduce the local air temperature that surrounds a building. Buildings behave like heat islands, and reduction of roof temperatures can have a positive affect on the ambient air outside of the building.

Maintenance Costs

Lowered roof surface temperatures can affect the lifetime of the HVAC equipment and of the roof itself. By reducing cooling demand, cool roofs reduce the number of operating cycles of the cooling HVAC equipment. While this is difficult to quantify, it is likely that the fewer hours an air conditioning system is in operation, the less often the equipment will need repairs and the longer it will last..

Solar radiation, especially ultraviolet radiation, and high temperatures are the leading causes of roof material failure. As the daily temperature cycles, incident radiation degrades the surfaces, causing them to become brittle and crack as shown in Figure 2-40. By lowering the amplitude of these temperature cycles cool roof coatings can extend the life of roofing materials by several years. In the case of green roofs, the system completely isolates the roofing membrane from the weathering elements and the temperature is held relatively constant under the protection of the mass of the green roof, both during the summer and winter months.

Figure 2-40. Examples of deteriorating asphalt shingle roofs on residential homes in Phoenix. Photos courtesy of National Center of Excellence, Arizona State University.

RoofingAction Plan

The cool roofing technologies described in the previous sections are commercially available and have proven their benefits over the last decade. They are not standard practice in the Phoenix region, possibly because of limited public and government awareness of them. This section of the report proposes actions and strategies for implementing cool roofing in the Phoenix

region.These strategies are based on similar cool roofing plans that have been successful in California, Georgia, Florida, and Texas, demonstrating that local governments can plan successfully to address this key component of UHI mitigation. In order to be effective, region wide cool roofing implementation plans must:

• Target buildings that have the highest potential for utilizing existing cool roofing technologies;

• Provide information on cool roofing to the key decision makers, including building owners, contractors, and public officials;

• Establish new municipal codes and regulations that specify cool roofing requirements and adopt existing energy code provisions;

• Provide economic incentives for cool roofing;

• Create visible demonstration projects through public partnerships and leadership; and

• Increase public awareness.

This section provides detailed examples of each of these components. Incorporating these components into city action plans will have immediate impact on energy consumption and UHI formation in the Valley. Phoenix and its surrounding neighbors have a great opportunity to become leaders in UHI mitigation and provide a role model for other urban centers located in hot, arid regions.

Target Surfaces

An effective development plan must focus its attention on specific targets. A target must possess the greatest potential for positive change. In the case of roofing it is important to select roofing types that are:

• a large percentage of the total number of roofs

• frequently being constructed or re-roofed

• receptive to cost effective and commercially available cool roofing solutions

• under the jurisdiction of building codes and municipal guidelines

Roofing surfaces in the Phoenix region account for 15% or more of the total developed area.The roofs are divided into two categories: steep sloped roofing and flat or low slope roofs. As discussed previously, cool roofing solutions are commercially available for both sloped and flat roofs. However, it is clear that flat roofs are more suited to the majority of cool roofing technologies. And in terms of contractor experience and availability, there are a significant number of cool roof technologies already being used on flat roofs in the Phoenix region. Many of these white reflective roofs were installed over the last two decades to reduce cooling demands of buildings.Yet, there are still many surfaces that are not using cool roofing products which could benefit from incentives and public awareness campaigns.

The majority of roof surface area in Phoenix is on residential homes. Ninety percent of these are sloped; only 10% of residential buildings, mostly multi-family units, have flat roofs. Most flat roofs are on commercial, retail, public, and office buildings comprising about 40% of the total roofing area in the Phoenix region.The average useful life of a roof material ranges from ten to thirty years. In Phoenix, however, flat roofs are expected to last for only ten years before requiring replacement or significant repair. Residential sloped roofs usually last longer, depending on the quality of construction and materials. Asphalt shingles can require replacing every 10 years, while tile roofs can last twenty or more years without routine maintenance. Metal roofs that are adequately coated with anti-rusting agents can have lifetimes of more than 30 or 40 years.

Given the availability of suitable cool roofing technologies, the relatively frequent re-roofing requirements, and potential energy savings, low sloped roofs present the best opportunity for implementing cool roofing technologies in the Phoenix region. Low slope roofs are therefore the main target for initial implementation of a cool roofing strategy. As cool roofing technologies for sloped roofs become available for residential applications, it is essential that homes with sloped roofs are added to the plan.With the rate of re-roofing projects in the Valley, within ten years nearly two -thirds of all flat roofing in the Valley could be cool roofing if the recommendations in this guide are implemented. According to studies of similar regions, this would increase the average roofing albedo of the Valley by nearly 70%. Table 2-6 shows the relative percentages of roof area, their recorded average albedo, and the projected albedos after a ten year plan to use cool roofing on all new and re-roofing projects in the Houston area

Table 2-6. Projected roof and albedo change over a 10-year period in Houston,Texas.

Providing Information to Building Owners and Managers

Building owners and managers are the most important decision makers when it comes to roofing choices. New guidelines are needed that include information on common practices, commercially available materials and suppliers, and technical support for the installation of cool roof options. While this guidebook provides an introduction to the variety of materials and the benefits of cool roofing, product summaries, and links to local suppliers, more detailed technical support from independent consultants and roofing specialists is necessary to implement cool roofing plans successfully. In addition to written materials, business and professional organizations should conduct workshops, seminars, and product demonstrations for building owners, managers, and roofing companies.This would ensure that all stakeholders and decision makers are adequately informed about the benefits and availability of cool roofing technologies.

Changing Codes

Municipal codes are established to maintain quality, safety, functionality, and consistency of buildings. Incorporating cool roofing requirements into these codes would be the most effective way to ensure that they are implemented in construction. Changing building codes is not an easy process and requires the support of trade, business, and community leaders. Considerable time and effort is involved in changes to codes and this should be considered only when the community stakeholders are sufficiently informed about the benefits and methods for implementing cooling roofing.

Economic Incentives

The rate at which cool roofing is installed can be increased by providing economic incentives to end users. The State of California developed a project that offered incentives ranging from $0.15 to $25 per square foot of roofing for installing reflective roofing materials.They estimated that 20 megawatts of peak energy demand was offset for every 60 million square feet of cool roofing. Utilities can also offer incentives for demand -side management. In Austin,Texas, the local utility, Austin Energy, provides a similar rebate of $0.10 per square foot of cool roofing constructed. Other incentives could include property tax deductions as part of a state energy program where the local jurisdiction could be reimbursed by the State to make up for lost tax revenue.

Widespread Use of Energy Code Provisions: ASHRAE 90.1

The Energy Standard for Buildings, Except Low-Rise Residential Buildings (ASHRAE 90.1), produced by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE), has provisions that allow the reduction of insulation within roof assembly when cool roofing is used. The roof must have a reflectance of 0.70 and a thermal emittance of 0.75. Potential insulation reductions of 14-23% are possible under this energy standard, depending upon the climate conditions in which the building is located. Architects, builders, engineers, developers, and building owners need to be reminded that this provision exists and that they should take advantage of it. Several cool roofing technologies cost nearly the same as standard roofing material and offer opportunities to save in other areas of building construction under well established energy standards such as this one.

Creating Visible Public Partnerships and Leadership

The best way to publicize the availability and utility of cool roofs is to conduct demonstration projects on highly visible public buildings. Buildings belonging to school districts, community colleges, and public universities; transportation centers; and hospitals are potential candidates. Taking a leadership role and setting an example can bring positive attention to these institutions and help promote knowledge and awareness of cool roofing to the general public.

Increasing Public Awareness

Public awareness of cool roofing technologies is essential for change. Citizens must be knowledgeable about changes in building codes, homeowner’s association guidelines, and other restrictions that may have an impact on them. In addition, economic incentives such as tax credits or rebates have to be clearly defined and understood by building owners in order to be used effectively. One strategy to increase awareness is to publish case studies, news stories, and video documentaries about cool roof projects in the Phoenix area. The benefits of each project, cost savings, and interviews with the building owners are important components to include. Consistent, persuasive public information is vital to promote the adoption of cool roofing practices and other urban heat island mitigation strategies.

StepsTowardImplementation

• Form a Cool Roof Steering Committee of various agencies and stakeholders to oversee the implementation of heat island mitigation measures for cool roofing actions.

• Work with the City of Phoenix to set goals and implement cool roofing projects, including the identification of cool roofing opportunities in City owned buildings. Similar actions are needed with school districts, school buildings, and other local governments.

• Work with the Arizona Department of Environmental Quality (ADEQ) to develop a strategy for including cool roofing in the State’s air quality plan.

• Work with appropriate officials to ensure that the state energy code includes explicit provisions for reflective roofing and green roofing technologies.

• Working with the ADEQ and EPA, develop specific, credible methods of mitigating the heat island effect to help ensure compliance with the Clean Air Act and Clean Water Act.

• Work with the Maricopa Association of Governments (MAG), other planning organizations, and cities within Maricopa County to incorporate heat island mitigation measures such as cool roofing into community planning and development activities.

• Establish a roofing baseline for measuring progress in achieving cool roofing goals that helps establish a means of verifying air quality credit.

• Work with the Steering Committee to design and launch a cool roofing education, training, and outreach program for state and local agencies, building owners, building mangers, and roofing industry companies and organizations.

Adapted from HARC (2004)

PAVEMENTS

The economic vitality and quality of life within an urban area are often related to the quality of its transportation system. Nearly half of the developed area in the Phoenix region is dedicated to transportation and is paved with dark, dense, and impervious materials that are the most significant contributors to urban heat island formation. Paved surfaces include the networks of highways, roads, parking lots, driveways, and sidewalks that provide for the movement of people, goods, and services and are vital to the economic success of the region. According to the Bureau of Transportation Statistics (BTS), the United States spends about 11% of its annual budget on transportation and these systems account for nearly 16% of U.S. Gross Domestic Product

Figure 2-41. Transitioning surfaces from desert to engineered surfaces such as parking lots.

(BTS, 2006). Recent advances in pavement design have resulted in “cool paving” materials and designs that can significantly reduce heat absorption and retention of surfaces. This section of the guidebook focuses on cool paving technologies that are currently available for new construction, maintenance, and reconstruction projects throughout the region. Here we define and quantify each pavement type for the Phoenix region, review cool paving solutions and their relative costs and benefits, and suggest how to incorporate cool paving in current and future development projects.

Figure 2-42. ASTER satellite image of surface temperature in the Phoenix

metropolitan area at night. The warmest 20% is highlighted in red. Image courtesy of Arizona State University.

PavingApplications

Paved surfaces can be categorized by their functional characteristics. These include location, number and size of vehicles that traverse the pavement, and the distance and speeds that will be traveled upon it. For the purposes of this guidebook pavement applications are grouped into seven categories: Highways, Arterials, Collectors, Local Roads, Parking Lots, Sidewalks, and Driveways. Engineering requirements can vary greatly among these categories, and performance requirements will dictate which cool paving solution is most appropriate for each application. Defining categories also helps decision makers target the pavements that are likely to be replaced or reconstructed most frequently. Figure 2-43 highlights the spatial relationships among the four different types of road networks.

Figure 2-43. Four basic roads categories in a typical urban area. Source: Google Earth.

Highways

Highways are the conduits that carry vehicular traffic across regions. They can range from rural, two lane roads to multi- lane pavements in major metropolitan areas. They must be designed to support nearly constant loads, ranging in size from motorcycles to large commercial shipping vehicles with six or more axles that exert over 25 tons of force on the pavement.

Speed limits on highways are the fastest in an urban area, up to 75 mph. To support these loads, highways are often made of engineered materials several feet thick. The surface typically consists of rigid or flexible pavement that is supported by layers of base and sub-base materials. Figure 2-44 shows a typical multi-lane highway near Phoenix, Arizona.

Figure 2-44. Multi-lane highway in Phoenix, Arizona. Photo courtesy of National Center of Excellence, Arizona State University.

Arterials

Arterials are roads that connect directly to major population centers.They link to highways and serve as the major distributors of urban traffic within a city. Arterials can be two to six lanes across and are typically made of flexible pavements with substantial base support materials. These roads can stretch the entire length of metropolitan areas, connecting multiple urban centers. Arterials vary greatly in capacity and traffic volume. Some two lane arterials are traveled by 10,000 vehicles a day, while six lane arterials often have 75,000 vehicles per day. Arterials have lower speed limits (30-45 mph) than highways and are integrated with traffic controls systems such as stoplights at major intersections. Figure 2-45 shows an arterial street in Phoenix.

Figure 2-45. An arterial street and adjoining sidewalk in Phoenix. Photo courtesy of National Center of Excellence, Arizona State University.

Collectors

Collectors link arterials to provide a balance between mobility and direct access to land within residential, industrial, and commercial areas.They typically have fewer than four lanes made of flexible pavement, with sidewalks located on either side. Speed limits range from 25-35 mph, and the roads can handle from 5,000-10,000 vehicles, depending upon the number of lanes.

Local Roads

Local roads are the roads that run through residential neighborhoods.These streets are typically constructed of full depth, flexible pavement and can have rounded curbs and sidewalks on both sides. Speeds are typically between 20 and 30 mph and the roads usually serve fewer than 5,000 vehicles per day.

Figure 2-46. Parking lot outside of a major commercial facility in Arizona. Photo courtesy of National Center of Excellence, Arizona State University.

Parking Lots

Vehicle parking lots are typically constructed of flexible pavement several inches thick. Parking lot speed limits are usually 5 to 15 mph, and the number of vehicle spaces can vary greatly depending upon the type of facility the lot serves. Figure 2-46 includes a typical parking lot; this one is located at a shopping mall in Tempe, Arizona.

Most commercial parking lots are constructed of 4 to 6 inches of flexible pavement, such as hot mix asphalt, over a crushed aggregate base. Figure 2-47 shows the cross section of a parking lot located in Tempe, Arizona.

Figure 2-47. Cross-section of an asphalt parking lot located in Tempe, Arizona. Photo courtesy of National Center of Excellence, Arizona State University.

Sidewalks

Sidewalks are paved surfaces for pedestrian and bicycle traffic.They can be found along major arterials, connectors, and local roads, or in any location where a permanent path is desired. In most cases sidewalks are made of a thin layer of concrete or block pavers.They can often reach temperature of 150ºF (65ºC) during the day as shown in Figure 2-48.

Figure 2-48. Visible and infrared images of pedestrians walking over pavements with temperatures of over 150ºF. Images were taken in July 2006 with a peak air temperature of 100ºF. Photos courtesy of National Center of Excellence, Arizona State University.

Driveways

Driveways provide vehicular access to buildings or parking facilities. Traffic volumes can vary greatly and structural design is dependant on the size of the vehicles to be accommodated. A commercial driveway leading to a loading dock will be much thicker than a residential driveway connected to a house.

Paving in the Phoenix Region

Phoenix and its surrounding cities are one of the most pavement rich areas in the country and rapid growth adds many more miles of new roads, highways, and parking lots every year. Landcover studies performed in other cities have shown that nearly half of all pavements in urban regions are designated for parking. For example, in Houston nearly 217 square miles of pavement is for parking, while 125 square miles is roads (Rose et al. 2003). Parking lots cover 15% of the total land area for the entire Houston region. Preliminary findings of landcover studies at ASU show that parking lots in Phoenix account for closer to 18% of the total land cover.That is more area than all of the building roofs combined. Research is currently underway at ASU to accurately quantify types and surface area of pavements in the Phoenix region

Eighty-four percent of all roads in the US are constructed of asphalt concrete (AC).The second most common paving material s Portland cement concrete (PCC). In Phoenix, the majority of streets are made of asphalt concrete and the highways are typically constructed of PCC. Over the last decade, rubberized asphalt has become widely used for major arterials and as a highway overlay on top of PCC. Rubberized asphalt is simply that, crumb rubber (mostly from used tires) mixed with conventional asphalt concrete. The result is a flexible pavement that is on average four decibels quieter than asphalt or concrete pavements. The Arizona Department of Transportation (ADOT) first used rubberized asphalt in 1964, and in 1989, Phoenix began its use and continues to use it more than any other city in the world. According to ADOT, the benefits of using rubberized asphalt are that it fills in cracks in the existing pavement during repairs, it is more durable and skid-resistant, and it reduces traffic noise and provides a smooth, quiet ride. However, the albedo of rubberized asphalt is especially low. Conventional and rubberized asphalt albedo can range from 0.20 to as low as 0.04 when brand new. Over time, with traffic wear and degradation caused by ultraviolet radiation, asphalt pavement becomes lighter. PCC, on the other hand, starts out with a 0.40 albedo and over time it loses its reflectivity, becoming darker (albedo = 0.25) due to tire deposits and grime build up.The lower albedo of both of these conventional paving materials can result in surface temperatures that far exceed the ambient air temperature. Figure 2-49 shows an example of the difference between surface temperatures of asphalt and concrete in Rio Verde, Arizona on a 95ºF afternoon.

Figure 2-49. (a) Visible and infrared image of concrete parking next to new asphalt sealed road located at Rio Verde,Arizona, during June 2006 (ambient air temperature 90ºF); (b) Hand held thermometers verify this temperature difference on the ground. Photos courtesy of National Center of Excellence,Arizona State University.

Figure 2-50. Example of pavement material variations on the south airfield at Sky Harbor International Airport

in Phoenix.Asphalt cement concrete can vary from 0.05 to 0.15 albedo, depending on its age.

Source: Sanborn

The low thermal performance of both of these conventional materials has contributed to urban heat island formation in Phoenix. Completely replacing all pavements with new material is not economically feasible. Asphalt is the most inexpensive paving option in the country, accounting for its domination in the paving materials market. Both asphalt concrete and Portland cement concrete are appreciated for their strength, durability, and longevity under the demanding loads and harsh environments to which roads are subjected. Luckily, new modifications to these existing paving materials can greatly improve their thermal performance while still taking advantage of their well established ability to meet structural and durability requirements.The cool paving materials and surface treatments presented here are rooted in the conventional materials of asphalt and concrete. For this reason, they can be easily adopted in pavement projects and construction without requiring a lot of redesign by engineers, planners, and contractors.

PrinciplesofCoolPavingTechnologies

Cool pavements are pavements that absorb less solar energy than conventional paving materials under identical environmental conditions. Although there is no industry standard established yet for what constitutes a cool pavement, there are several key elements that indicate the potential for a surface to absorb less energy. These four elements are essential to cool pavement materials and designs.

Reduce Direct Solar Exposure

Perhaps the simplest but most effective means of reducing the amount of solar energy absorbed by pavements is to prevent the sun from reaching it in the first place. This can be accomplished in several ways, dependent upon the pavement application and function. Consideration of the location of the sun during different seasons is very important to maximize shading. Certain paved surfaces such as parking lots, sidewalks, and driveways are easier to shade than roads and highways, for obvious reasons.

Parking shade structures are commonly used to shade automobiles; however, they are also beneficial for reducing the heat

Figure 2-52. Shade parking canopy. Photos courtesy of National Center of Excellence, Arizona State University.

Figure 2-53. Solar shading canopies reduce temperatures, increase pavement life, and produce power for lighting and building.This lot, located in San Diego, California, provides parking for 186 vehicles while generating 235 kilowatts of electrical power. Photo courtesy of Kyocera Solar, Inc.

absorbed by pavements. Structures such as metal awnings, stretched fabric, and tree canopies block direct thermal rays of the sun. Metal structures are most effective if they are designed with gaps that allow hot air to rise and pass through them. While metal canopies can often reach high temperatures during the day, their thin structure retains less energy and their large sky view helps to release the energy quickly after sunset. A study conducted at ASU showed that photovoltaic paneling systems can provide shade while generating electrical power for onsite uses such as lighting at night. (Golden and Carlson 2006).

When funding permits, constructing parking areas below ground is highly recommended.This completely isolates the parking area from the sun’s energy while also increasing the amount of area above ground that can be used for vegetated landscape walking areas or additional building space.

Figure 2-53. Example of underground parking in a commercial shopping center. Photo courtesy of Tunnerl-Spangler-Walsh & Associates.

When choosing vegetated shading like vine canopies and trees, it is important to choose species that will require little maintenance (trimming, watering) while providing adequate shading during the summer months.The following section on urban forestry provides more information on native species and their effectiveness for shading in the Phoenix bioclimatic region

The US Green Building Council’s LEEDTM    rating system recognizes shade as an effective means of mitigating the urban

heat island effect in parking lots. LEED TM    credits can be awarded for constructing 50% of the parking surfaces underground,

shading with structures, or covering by growing tree canopy within five years of   construction completion) (LEEDT                                                                                                                                                                                                                                                                                            NC Version 2.2 Reference).

Figure 2-54. Pavement temperatures versus albedo. Source : Gui et al. (2006).

Increase Surface Reflectance and Emittance

If direct sun exposure is unavoidable, the next best opportunity to limit the heat gain of pavements is by reflecting it. Albedo is the ratio of solar energy reflected by a surface to the amount striking the surface. Increasing the albedo of surface pavements has been shown to reduce the surface temperature and heat retention of pavement more than any other material property. In fact, a 10% increase in albedo of a pavement reduced the surface temperature by 7.2ºF (4ºC) (Pomerantz et al., 2000). A decrease in surface temperature can also greatly reduce the temperature gradient within a pavement. This gradient differential causes stresses within the pavement layers that can result in cracking and greatly reduces the pavement life. Solar reflectance has never been included in pavement requirements before, but is recommended.

Very few material have even close to 100% solar reflectivity (albedo=1); therefore, all materials absorb some energy. A portion of the absorbed energy is emitted as radiation to cooler surfaces and the sky while the rest is transferred to the ambient air through convection. Concrete, asphalt, soil, and rock are high emitters, with emittance values of 0.90 and higher.

A common misconception about high albedo pavement surfaces is that glare from the surface will affect driver visibility during the day and at night. This is not the case, as pavements like concrete are diffusive, reflecting light equally in all directions. This is the opposite of a metallic surface, which is specular and reflects light at angles. Only when pavement surfaces are wet is glare a problem, which has little to do with the albedo. Glare on wet surfaces can be reduced by increasing porosity on asphalt pavements and by tining concrete surfaces. Studies comparing reflective surfaces at night show high albedo actually increases safety and visibility for drivers by reflecting more of the headlight glare towards pedestrians or other objects in the road.

Figure 2-55. A high albedo surface under direct sunlight, showing diffuse reflection.

Increase Porosity

Porosity is a measure of air in a material. Surface materials with higher porosity will have lower thermal conductivities and volumetric heat capacities because air is a poor heat conductor and has very low density. An increase in porosity can significantly reduce the amount of energy that can be stored in a surface. Like soil and decomposed granite landscaping, the surface of porous materials can get hot during the day, but the heat is only stored in the top few inches. After sunset, the energy stored in this top layer is released rapidly due to the surface characteristics of porous materials. The surface of some types of porous pavement is very rough, and those cavities help cool the surface by allowing more surface area to radiate, transfering heat to air that passes across it.. A secondary benefit of porosity is retention of storm water.The more porous a material, the more likely the air

Figure 2-56. Insert plot of density versus pavement maximum and minimum temperatures. Source: Gui et. al, (2006).

spaces will interconnect. This interconnection creates channels that allow water and air to pass through the structure, making it permeable. Water can then be retained on site to benefit the vegetation and trees that surround a parking lot. One downside of surface roughness is that reflectivity is reduced, as smooth surfaces reflect more effectively.

Increase Evapotranspiration

Surface pavements that retain moisture stay cool by means of evapotranspiration. Similar to vegetated surfaces and soil, if a moist surface is heated by the sun, part of its thermal energy is expended in converting liquid into vapor. As this vapor leaves the pavement surface, it takes away heat and cools it similarly to the way skin sweats. Only a few pavement types do this effectively and they will be discussed below.

Cool Paving Materials

The cool paving materials described in this section maximize one or more of the three beneficial characteristics described above: increase albedo, increase porosity, or increase evapotranspiration. While none of the materials is extremely effective at all three, they are the best options currently available. With further research and investment in alternative products, this list will grow and change.

Pavements are comprised of two primary components, a binder and aggregates. Binder is the glue that holds the pavement together, either made of asphalt, Portland cement concrete, or emulsified polymers. Specific binders are chosen for different climate conditions. For instance, an asphalt binder used in the cold regions of Canada performs very differently from those used in climates like Arizona. The aggregate is usually crushed rock, which provides the strength, durability, and friction of the pavement.The type of rock used typically depends on whatever is available in the local area. Aggregate size can range from over one inch in diameter to fine sand, depending on the type of pavement and its application.The albedo of the pavement depends on the albedo of the binder and aggregates. In the case of asphalt, nearly 75% of an asphalt pavement is dependant on the albedo of the aggregate that is exposed at the surface (Pomerantz et al. 2000). Surface properties of pavements change over time due to the effects of weather and maintenance methods. Asphalt gets lighter over time, while concrete becomes darker.

Portland Cement Concrete

Particles that form a bond when mixed with water are referred to as hydraulic cements. The most common of these in the construction industry is Portland cement. Portland cement is made by mixing calcareous (lime coated) materials with argillaceous (clay) materials (Brantley and Brantley 1996). The raw materials of lime, silica, aluminum oxide and iron oxide are mixed in specific proportions.The mixture is then sent to a kiln, where temperatures close to 2700ºF (1482ºC) drive a chemical process that produces hard pellets of a material referred to as clinker which are ground into Portland cement powder.

Portland cement, when mixed with fine and coarse aggregate, air, and water is the basis of Portland cement concrete (PCC).

Figure 2-57. Portland cement concrete parking lot in Tempe, Arizona.Photo courtesy of National Center of Excellence, Arizona State University.

PCC is initially very plastic, perfect for casting or molding, which solidifies by a chemical reaction (Brantley and Brantley 1996). Portland concrete provides engineers with a low cost, easy to place, strong, and durable material.

New roads made of PCC are usually eight inches thick and can have lifetimes of over 35 years. PCC surfaces similar to the parking lot shown in Figure 2-57 typically have an initial reflectance of 0.35 to 0.40 when new, but over time, dirt, grease, and tire residues can lower its albedo to less than 0.25. By using lighter colored cement, aggregate, and sand, PCC can attain initial albedos of 0.40 to 0.80

White Cement

White cement is made using the same process as PCC, but kaolin is substituted for ordinary clay. (The iron oxide in clay is responsible for the gray color of PCC.) Because solar reflectance is not usually specified in engineering requirements, white cement use is uncommon and currently nearly twice the price of normal cement. Because albedos of 0.80 are possible with the use of white cement, it is desirable that cement suppliers find new methods or additives for increasing the albedo of their products.

Figure 2-58. Albedos of white and grey cement with identical aggregate proportions. Source: Levinson and Akbari (2001).

WhiteTopping

White topping is an industry term for a 4-to-8-inch layer of conventional Portland cement concrete laid over new or existing asphalt pavement.The name is misleading because the surface is gray, not white, in color. Because it is made of cement concrete, the surface radiative properties are the same as those of cement, with albedo ranging from 0.25 to 0.40.

Ultra thin white topping is a fiber reinforced cement concrete layer only 2-to-4-inches thick. It is particularly useful for dealing with intersection crosswalks that have elevated surface temperatures impacting pedestrian traffic. Because of high surface temperatures and continuous loads from braking vehicles, asphalt pavements at intersections suffer from rutting, shoving, and cracking. White topping creates a cooler surface and ambient temperature, increases pavement strength, and reduces life cycle costs.

Figure 2-59. A thin white topping project in Phoenix: (a) grinding down the existing asphalt base, and (b) curing the final surface. Photos courtesy of National Center of Excellence, Arizona State University.

Interlocking Block Pavers

Block pavers are made of precast concrete and come in a variety of shapes, designs, and colors. The albedo of these pavers varies greatly, but the lighter the color, the higher the albedo. The strength of block pavers is derived from their interlocking design. Each block is support by the pavers surrounding it, and the load is distributed horizontally. Block pavers are typically used in low traffic areas such as parking lots, turn lanes, and driveways. Some designs are made to be permeable with open joints that allow water to pass through while still maintaining tight wall-to-wall contact. Some cities use block pavers to fill in utility cuts because they can be dug up and replaced in a relatively short period of time and are considered more aesthetically pleasing than conventional repair materials.

Figure 2-60. High albedo, interlocking block pavers. Photo courtesy of LCRA Service Center, Austin,Texas.

Asphalt Cement Concrete (ACC)

Asphalt is a black or dark brown residue from the petroleum distillation process. Consisting of hydrocarbons and their derivatives, asphalt is used for many applications that require durable, weather resistant characteristics. One such application is asphalt cement, which is used in the construction of flexible, high grade pavements. Asphalt cement, when used as a binder mixed with aggregates such as gravel, sand, and crushed stone, is referred to as asphalt cement concrete (ACC). Since the turn of the century, ACC has been the most commonly used paving material for roads, parking lots, and highways.

The majority of ACC used for roads and parking lots is “hot mix asphalt” (HMA), produced by mixing aggregates and asphalt cement at elevated temperatures in either a batch or drum mix asphalt plant (US Army Corps of Engineers 2000). HMA is typically divided into three different mix types; dense graded, gap graded, and open graded.These names correspond to the size gradation of the aggregates in the mix

Figure 2-61. Cross section of three aggregate types found in hot mix asphalt. Source: National Asphalt Pavement Association.

Newly constructed asphalt can be one of the hottest surfaces in an urban setting, often reaching temperatures of 160ºF (72ºC) during summer days, due to its very dark, non-reflective surface (albedo=0.04). As asphalt ages, its albedo increases; however, it rarely exceeds 0.15 before being resealed with a dark asphalt sealant. Asphalt concrete is not considered a cool paving material, but adjustments in its mix design could greatly improve its thermal performance.

Figure 2-62. New and old asphalt surfaces in the Valley. Courtesy of National Center of Excellence, Arizona State University.

CoolAsphalt Concrete

Cool asphalt paving is constructed using lighter colored aggregates and sand. Changing the color of the binder is difficult and costly, but changing the aggregate is relatively easy. And because nearly 75% of an asphalt surface is made of exposed aggregate, a 30-40% increase in the aggregate albedo will result in a pavement surface that is 10-30% more reflective. As the asphalt binder ages, the surface will become lighter. Because the aggregates that contribute to surface reflectance are only at the surface, only the last lift (layer) of asphalt needs to incorporate the lighter colored aggregates. This reduces the supply problem for lighter colored aggregates in areas where they are less available or more costly.

Figure 2-63. A road made of asphalt concrete with reflective aggregates. Courtesy of the Asphalt Pavement Alliance.

CoolAsphalt Resurfacing and Coatings

Aged or damaged asphalt pavements are usually maintained with chip seal or slurry seal. These thin layer (< 0.5 inches) treatments help to rejuvenate roads and parking lots and are the best options for increasing asphalt surface reflectivity.

Gritting

Gritting is a type of chip sealing that spreads small, uniform aggregate over a freshly laid layer of hot, emulsified asphalt. It is used mainly on low traffic roads to increase skid resistance and the useful life of pavement. By using highly reflective aggregates it is possible to raise the pavement surface albedo significantly. The top layer of the gritted surface is exposed shortly after construction due to normal traffic wear and weathering effects. Although the aggregate is usually coated before it is laid down, it is possible to apply uncoated aggregate to the surface. This will produce immediate results, although the adhesion of the aggregate may be reduced if not compacted immediately after placement. Gritting is usually applied to older surfaces but it can also be used on new overlays to increase the albedo of the conventional pavement underneath.

Figure 2-64. Gritting requires a spreading truck to deposit reflective aggregate to hot asphalt emulsion. Source: Asphalt Pavement Alliance.

Slurry Seal

Slurry seal consists of a mixture of emulsified asphalt, aggregate, water, and specified additives. Slurry seals are applied over existing pavements to reduce oxidation, seal surface cracks, and stop raveling and loss of materials from the underlying pavement. Slurry seal also makes surfaces impermeable to air and water and can improve skid resistance by increasing the surface roughness. The aggregates used in slurry seals are very small, and if made of a high albedo material, can dramatically increase the surface reflectivity. The only limitation to slurry seals for cool pavement purposes is that they are well mixed to thoroughly coat the aggregate, creating a smooth, dark final surface. With time and wear the aggregate will be exposed, making the increased reflectivity a delayed result. Gritting offers a more immediate benefit over slurry seals because their aggregates are exposed directly during construction.

Figure 2-65. New technologies such as shot-blasting are being developed to lighten asphalt pavement immediately after construction.This technique abraded the surface binder

Photo courtesy of the Asphalt Pavement Alliance

Tinted Asphalt Binder

Originally developed for decorative purposes, light colored seal coats have a major potential for increasing the albedo of new and existing asphalt pavements for roads and parking lots.Traditionally, seal coats were applied to existing parking lots to improve the appearance, limit ultraviolet degradation, and reduce moisture damage. However, light colored seal coats also result in lower surface temperatures, which increase the life of the pavement underneath.

Figure 3-73. Example of a light colored synthetic binder using reflective aggregate. Photo courtesy of the Asphalt Pavement Alliance.

Reflective asphalt coatings are not yet widely available. Several pilot projects may be required in the Phoenix area before contractors begin to make this product commonly available and economically competitive with conventional surface treatments

Crumb Rubber Friction Course (CRFC)

Recycled crumb rubber added to asphalt friction coarse pavements results in a unique flexible pavement material widely used in urban regions to reduce highway noise by up to 6 decibels. A crumb rubber friction course is placed in a 1-to-2-inch thick overlay of standard 12-14 inch structural Portland cement concrete pavement . These kinds of pavement designs have initially proven to reduce surface temperatures at night more than conventional Portland cement concrete pavements (Belshe 2006). This phenomenon is attributed to the porosity of the top friction course in comparison to conventional PCC mix.There are up to 8% air voids in CRFC pavement, and combined with the higher convection generated by automobiles traveling at high speeds on freeways, the pavement’s porosity helps to reduce pavement temperature at night. However, the lower albedo of the black rubber tire and asphalt mix tends to elevate daytime temperatures in comparison to PCC. Additionally, an asphalt friction course may not function appropriately in some slower speed applications as it has less resistance to deformation due to its lower viscosity compared to traditional hot-mix asphalt. It can be used on arterial streets but is not recommended for parking lots or residential streets.

Figure 2-67. Despite its low albedo, crumb-rubber friction course overlays may stay at the same temperatures as Portland-cement concrete in areas of high traffic volume due to convection at the surface. Areas without traffic, such as the highway shoulder in this image, still reach comparatively warmer temperatures during the day. Images courtesy of National Center of Excellence, Arizona State University.

Open Grid and Permeable Pavements

Open grid and permeable pavements are unique alternatives to conventional PCC and ACC designs for parking lots and low traffic roads.There are a number of benefits associated with both types of pavements. Open grid pavements have large openings (50% of the total area) which can be filled with material such as soil or gravel. In some instances the soil is vegetated with grass. Open grid pavements are suited for low speed, low volume areas such as parking lots, long term parking areas, and fire truck access areas near buildings. Open grid systems provide an alternative to conventional pavement that is cooler, more natural looking, and permeable, yet strong and durable enough to support vehicles. A variety of the open grid pavements are shown in Figure 2-68. The USGBC’s LEEDTM Rating systems recognizes open grid pavements for their ability to help mitigate Urban Heat

Islands. In LEEDTM   Sustainable Site Credit 7.1 building designers can achieve one point for using an open grid system for over

50% of the project’s parking lot area.

Permeable concrete pavements include Portland Cement Pervious Concrete (PCPC) and Porous Asphalt Concrete (PAC) Often referred to as ‘no-fines’ concretes, permeable concrete pavements use less binder and uniform aggregate (rock) sizes to create a network of interconnected voids that allow for water and air to readily penetrate the surface. These pavements are an ideal solution for non-roof storm water management. If designed and constructed correctly, PCPC and PAC pavements can serve as retention basins, eliminating all or part of the additional land typically required for storm water retention areas on the property. Pollutants such as hydrocarbons and heavy metals are washed into the pavement and infiltrates the subgrade where natural microbial activity in the soil filter and degrade them thereby improving groundwater recharge rates and quality. The minimum required permeability for subgrade soils under permeable pavement is 0.5in/hour. In areas where of clayey soil it is recommended to provide a back up drainage area in case of heavy rainfalls. The air voids in permeable concrete pavements also help to reduce the heat transfer and energy stored by these materials, however, the overall benefit to UHI reduction is not fully understood yet.  Most testing of this material has explored its ability to reduce storm water runoff and its ability to percolate

Figure 2-68. Open grid pavements come in a variety of designs and provide a cooler alternative for parking lots and other hardscapes.

Figure 2-69. Examples of an open grid parking areas comprised of stabilized granite: (a) East Valley Transit Facility, and (b) a residential complex in Tempe, Arizona. Photos courtesy of National Center of Excellence, Arizona State University.

water to the soil below the pavement. A recent study at ASU tested several pervious concrete pavers and found that their temperatures ranged from 5.4ºF to 9ºF (3°-5°C) cooler than impervious concrete of equal thickness and albedo. With moisture present, pervious concrete was 18º-27ºF (10°-15°C) cooler during the day than impervious concrete (Asaeda 2001). Additional research is underway to quantify this reduction under typical Phoenix region climate conditions in several pilot permeable parking lots. The observed reduction in surface temperatures at night is believed to be the combined result of several factors, including evapotranspiration at the surface, high percentage of air voids and surface roughness increasing heat loss through convection.

Figure 2-70. Pervious concrete parking lot outside of the Nelson Fine Arts Center at Arizona State University.

Photo courtesy of National Center of Excellence, Arizona State University.

Along with a reduction in heat storage, permeable pavements can help reduce microclimates by improving the health of parking lot shade trees. Trees planted in locations adjacent to impervious concrete often suffer high mortality because their roots are deprived of moisture and oxygen, elevated soil temperatures, and the tree root balls are compressed. Preliminary findings suggest that these problems can be mitigated with permeable concrete pavements. Using permeable pavements around the base of trees can increase the longevity and canopy size of trees that provide vital shade for hardscapes, parked vehicles and pedestrians. When used in combination with high albedo pavements, using permeable concrete pavements can be a great design strategy for improving the microclimate and stormwater management of parking lots. An example of this hybrid type design is shown in Figure 2-71.

Figure 2-71. A sample design for integrating tree shade with permeable and cool pavements in parking lots.

Illustration courtesy of National Center of Excellence and College of Design, Arizona State University.

While PCPC and PAC are highly encouraged to meet the stormwater requirements for LEED they are not recognized as pavement strategies for UHI mitigation by the USGBC. However, with more research results and modification to the designs they may be accepted for this credit in the future.Table 2-7 compares the key cool pavement technologies in terms of application use, solar reflectivity, cost per square foot, and expected useful life.

Comparing Cool Paving Options

While cool asphalt concrete is the cheapest of all paving solutions in terms of upfront costs, installed cost does not consider the additional expense required to maintain and replace the pavement at the end of its useful lifetime. Cement concrete can last up to 35 years and asphalt concrete is only rated for ten years in most situations. Long term costing can level the playing field for materials with high initial costs but significantly longer anticipated operational lives.

Table 2-7. Cool paving technology applications, use, benefits, cost, and life expectancy. Source: Houston Advanced Research Center, 2004.

Environmental and Economic Benefits of Cool Paving

Cool paving technologies can help to reduce air temperatures within cities by reducing the amount of solar energy absorbed by transportation infrastructure. Other benefits of cool paving may not be as apparent. Direct economic and environmental benefits include increased pavement life, greater nighttime visibility, and improved stormwater management. Indirect benefits include decreased smog formation, reduced energy and water demand, and fewer heat related illnesses.

Reduced Smog Formation

Smog in cities is formed when volatile organic compounds (VOC) from gasoline automobile exhaust are subjected to ultraviolet rays from the sun. As with all chemical reactions, the rate of reaction and formation of smog is directly related to the air temperature in which it occurs. And because conventional paving heats the near surface air at the same height as tailpipe exhaust, smog formation is significantly increased. Studies conducted in Los Angeles indicate that air temperatures at the surface level correlate with smog concentrations and incidence of illnesses related to air pollution (Akbari 1991).

Durability and Increased Lifetime of Pavements

The leading cause of pavement degradation in Phoenix is thermal stress. When pavement surface temperatures heat and cool throughout a daily cycle, the pavement is stressed between the top and bottom surfaces.This daily cyclical stress can eventually crack and warp the pavement. The time it takes for a surface to crack is directly related to the magnitude of the temperature swings to which it is subjected. It is not uncommon to observe surface temperatures of 85ºF (30ºC) for low albedo pavement at 5:00 a.m. rising to 160ºF (70ºC) at 1:00 p.m., and then falling back to 85ºF (30ºC) the following morning.

Surface temperature swings of 75ºF (42ºC) result in major stresses that take their toll over time. The constant heating of pavement surfaces and the penetration of UV radiation degrades the oils and resins in the binder, causing the pavement to become brittle and crack or unravel. Finally, at 160ºF (70ºC), asphalt binder becomes soft and the pavement will actually deform under heavy traffic loads caused by braking or turning, resulting in permanent deformations such as rutting or shoving. When this type of failure occurs, the pavement becomes unsafe and needs to be replaced. In some intersections within Phoenix, pavement lanes are replaced every three years due to rutting and shoving.

By lowering surface temperatures of asphalt concrete with the cool asphalt techniques described above, the lifetime of these surfaces can be increased by several years, thus reducing the amount of money required for maintenance, repair, and removal of thermally stressed pavements. This savings alone can offset the upfront costs associated with alternative pavement designs (Pomerantz et al. 2000).

Nighttime Safety

High albedo pavements are meant to reflect solar energy. An added benefit is that they generally reflect visible light from artificial light sources such as street lamps and sidewalk lampposts. By reflecting more visible light, these surfaces increase the amount of light in an area, improving nighttime visibility in urban areas and on the road. Studies indicate that pedestrian and driver safety is increased at night in areas with high albedo surfaces. The reflected light from a high albedo pavement provides greater illumination of a pedestrian or object in the road than does the light of street lamps and automobile headlights over a dark surface

Some city planners have expressed concern that white pedestrian crosswalk striping in the road is not as visible to drivers when high albedo pavements are used.This concern is not valid because the crosswalk striping is not meant for drivers to see but rather for the pedestrian’s awareness (Ziedman 2005). Brightly colored yellow crosswalk signs perpendicular to the pavement surface inform drivers about crosswalk areas.

Lighting Demand

An additional benefit of higher albedo pavements at night is the decreased need for energy for road and sidewalk lighting. Increasing the amount of light reflected from driving and walking surfaces allows low energy lighting systems like light emitting diodes (LED) to be used and the spacing between lights can be increased, requiring fewer light fixtures for the same area. One study showed that a road with asphalt paving required 39 light fixtures per mile to meet required roadway lighting levels, but when the same road was repaved with a more reflective concrete, only 27 light fixtures were needed per mile to meet the requirement. This decrease in lighting of 31% equated to a financial savings of $24,000 per mile on construction, $576 per mile per year on maintenance, and $600 per mile per year on energy bills (Stark, 1984). Unfortunately, transportation designers do not take into consideration the type of road material being used for a project when determining how many light fixtures are required per mile along roadways, but typically use worst case scenarios associated with new asphalt for lighting calculation purposes.This is a huge cost savings opportunity, but will require a change in current design practices.

Stormwater Runoff

When it rains, natural surfaces slow the movement of water and much of it permeates the soil, benefiting vegetation and recharging aquifers. In highly urbanized areas, much of the land is covered with impermeable surfaces, and water that falls on these surfaces is either channeled into subgrade retention basins, sent through sewers to wastewater treatment facilities, or flows into nearby streams and bodies of water. Urban storm water contains automobile residues, landscaping pesticides, suspended solids, and other pollutants. These contaminates become concentrated in storm water collection areas and take a heavy toll on biological systems and municipal wastewater treatment facilities. Permeable pavement technologies help to capture and retain this stormwater runoff, preventing pollutants from leaving parking lots and driveways and concentrating in retention basins or sewers. This captured rainwater filters through soils, recharging underground aquifers, and improves the health of adjacent vegetation.These benefits are in addition to the evapotranspiration process that cools the surface due to stored moisture within the pavement.

PavingActionPlan

There are several ways to reduce the contribution of pavements to UHI formation within the Phoenix region. City governments must set forth a plan to address this key component of UHI mitigation. Many urban centers in the U.S., including Houston, Austin, Philadelphia, Sacramento, and several other California cities, have already begun to adopt cool paving practices. Of all of the metropolitan areas in the United States, Phoenix and its surrounding areas would benefit most from direct and immediate action to address the UHI effect. In order to be effective, regionwide cool paving implementation plans must:

• Target the surfaces of greatest potential benefit for installation of cool pavements during the next ten years.

• Educate key decision makers, including building owners and contractors, about local government requirements.

• Establish new codes and regulations for construction and maintenance procedures that incorporate cool paving strategies.

Provide incentives to adopt these new paving techniques and strategies. Phoenix has the potential to become the leader in proactive UHI mitigation in the nation.The region could serve as an example of best practices for urban centers that are developing in hot, arid regions around the world.

Target Surfaces

It is important that city administrators focus their attention on the pavement surfaces that present immediate opportunity for change. Many surfaces within an urban area, such as residential streets, sidewalks, and driveways, do not change very often. However, surfaces like older parking areas are resurfaced frequently, every five to ten years.The rapidly growing Phoenix region adds new pavements in residential and commercial areas every year. These new construction projects are great opportunities to immediately adopt cool paving for both streets and parking lots. Highways are also resurfaced continually and their shoulder sections present an opportunity to use high albedo treatments, as they are rarely under traffic loads.

Parking Lots:Resurfacing and New Construction

The first component of a cool paving implementation plan should address parking lots. Nearly 50% of all paved surfaces in the Phoenix region are parking lots, and they are resurfaced often, are subjected to medium traffic loads, and are more easily shaded than roads or highways. Constructing new or resurfacing parking lots with cool paving materials will have a significant effect on the UHI formation in the region.The benefits of high albedo will also improve the useful life of the lots and reduce the maintenance costs associated with thermal stresses

Road Expansion: New Streets in Residential and Commercial Areas

New road construction in the Phoenix region is another great opportunity to implement cool paving. Residential and commercial streets are rarely resurfaced and can remain unchanged for 15 to 35 years depending on the traffic volume. New road development in Phoenix will continue to flourish in the region, adding over 10% of the current roadway surface area in the next 10 years.This growth presents an unprecedented opportunity for cool paving implementation over the next decade.

Highways:Resurfacing and Shoulders

Highways seem to always be under construction in the Phoenix region. The harsh desert conditions and increasingly heavy traffic volumes necessitates resurfacing these pavements every 10-15 years. Most highway surfaces are now being covered with inch Crumb Rubber Friction Coarse described earlier.The rubberized asphalt creates a very low albedo (0.04) surface when brand new. By using white aggregate cool asphalt techniques, these CRFC high-performance roads can stay cool while serving as an insulation layer over the large concrete mass underneath.

Resurfacing highway shoulders may present an even greater opportunity for UHI mitigation than resurfacing the lanes. Highway shoulders, nearly the width of an additional lane on each side of the highway, are continually exposed to solar radiation and are not cooled by traffic movement, causing them to become the hottest pavement surfaces in an urban area. Because the shoulders are only used in emergency situations, their engineering performance and durability can be much lower than that of the lanes The highway shoulders can be constructed of white cement, cool asphalt, or resurfaced with a cool sealcoat to take advantage of an additional opportunity to reduce the urban heat island effect.

The Power to Make it Happen

Informing key decision makers (legislators, city officials, architects, engineers, planners, building owners, and cool paving suppliers) about cool paving options, their benefits and costs, is essential to successful implementation of a UHI mitigation plan. State officials responsible for implementing the Federal Clean Air Act and Clean Water Act need to be made aware that cool paving, along with other UHI mitigation strategies, can help them attain compliance. These same officials could develop a regulatory framework that recognize cool paving and provides incentives or credits for using cool paving throughout the region

Education and information distribution is also needed at the local level. Community leaders and city officials need to become knowledgeable about the impacts of and options available for cool paving in their areas. Local governments can take an active role in creating change by following these suggestions:

• Sponsor pilot and demonstration projects.

• Adopt cool paving as part of public works options for addressing air and water quality issues.

• Add solar reflectivity to performance standards for paving materials.

• Add cool paving to maintenance plans for pavements.

Adapted from Hitchcock (2004)

Trade and professional organizations in the Phoenix region can distribute information on the options, benefits, and costs of cool paving technologies to their members. These organizations can develop online information specific to their industries, including cool paving construction techniques, issues, and case studies. Cool paving workshops, certification courses, and demonstration projects will help increase awareness and create a base network of professionals who are familiar with cool paving designs and construction techniques.

Incentives and Regulations

Use of new paving technologies is often discouraged by their higher initial cost over conventional materials. Private property owners usually are concerned only about short term costs, and using cool paving materials can cut into their immediate return on investment. Governments should take a life cycle cost approach to paving projects by incorporating operational lifetime, maintenance costs, and environmental regulation compliance. Economic incentives can be an effective way to overcome the barriers to implementing cool paving technologies. Some incentive programs that have been implemented in other cities are:

Incentive payments, in the form of direct rebates, given to building owners and developers based on the square footage of temperature reduction of materials used for the roads and parking lots

Small property tax advantage for new or resurfaced parking lots that use cool paving;

• Reduction of sales tax on installation of reflective paving;

• Reduction of utility related fees where it can be demonstrated that cool paving reduces energy consumption or provides water management benefits; and

Pervious pavements counted as retention basins, reducing the amount of land required to meet storm water regulations.

Adapted from Hitchcock (2004)

Adjustments to building regulations may also be used to encourage cool paving. Green building rating systems such as the US Green Building Council’s LEED Certification already incorporate and award points based on cool paving technologies and materials for parking lots. These points are part of the Sustainable Sites Credit section, and one of the lead drivers in the rapid adoption of cool paving technologies in new commercial construction projects nationwide.

URBAN FORESTRY

Planting vegetation is one of the simplest and most cost effective ways to cool the Phoenix region. Trees, shrubs, and vines naturally cool the air, shade surfaces from direct sunlight, improve air quality, and enhance the aesthetics of urban areas.The direct energy savings from the shade provided for individual buildings is surprisingly high, and the collective cooling effect of an urban forest can have an even greater influence on energy savings for the entire community.

While the cooling benefits of urban forests are the main focus of this section, it is difficult to ignore the many other benefits of vegetation, including increased property value, noise abatement, storm water management, and soil stabilization. Another advantage of investing in trees is that these benefits will only increase with time as the trees mature. That’s definitely one thing you can’t say about roofing, pavements, and HVAC technologies.

Many people assume that increasing vegetation in the desert strains the region’s limited water resources. This is a very important point, so a regional tree planting plan should include only species that are native or can adapt to the local climate conditions. New grey water and rain water collection practices can offset the potable water used for landscape watering. The reduction in energy use that urban forests can provide significantly outweighs the amount of water required to support them.

While Phoenix has many mature landscaped neighborhoods that date back to the mid-twentieth century, new developments are quite different and comparably bare. As native desert is transformed into master planned communities, there are opportunities to conserve the native vegetation. By limiting the destruction of mature desert trees during initial site preparation, communities can conserve the character of the desert and limit the impact of development on wildlife diversity.

This section of the guidebook focuses on urban forestry in the Phoenix region, assessing current forestry practices and discussing the benefits of vegetation, including the economic benefits. Strategies are presented for reforestation and conservation and suggestions are provided to help governments, private companies, and citizens implement effective urban forestry programs n their communities

Trees and Vegetation in the Phoenix Region

An urban forest is defined as the whole community of trees and other vegetation found within city limits, a collective greenscape that provides environmental, economic, and social benefits for today and into the future. There has never been an inventory of the total number of trees in the Phoenix region. Studies using remote sensing satellites to measure the amount of vegetation in the region indicate that vegetation accounts for about 13% of the total land cover in Phoenix. Older neighborhoods with flood irrigation often have yards full of thick grass and large, broad-leafed, deciduous trees. This mesic landscaping resembles the yards found in the Midwest, where many of the early settlers in Phoenix originated. In the 1950s, water resources seemed bountiful and using lush landscaping to keep cool was perfectly acceptable for large, single-level homes. Most of the trees and vegetation were not drought tolerant and required large amounts of water and maintenance to survive the harsh Arizona summers.

As the city grew, flood irrigation was no longer used and new master planned communities began to use sprinkler systems to water grass yards. Since the 1990s, residential landscaping practices have increasingly incorporated native and drought tolerant plants. Decomposed granite, aloe, yucca, cacti, mesquite, and palo verde trees have become popular, low maintenance options for new homeowners in the suburbs. Many yards are designed with a mix of both desert and lush landscaping, resembling green golf courses surrounded by desert. This style is referred to as ‘oasis’ landscaping. The majority landscaping practices have been based on aesthetic considerations rather than on those of energy and water conservation, or urban heat island mitigation

Benefits of Forestry in Urban Areas

The benefits of vegetation are quite remarkable given the low cost and ease of planting. While the UHI mitigation effect of vegetation is dependent on factors such as density, shape, dimensions, and placement, benefits can be realized from almost any tree

Trees, shrubs, vines, and groundcover plants affect urban climate and energy use in two ways. Direct effects modify the way a building interacts with its surroundings, and include the shading and shielding effect of vegetation surrounding a building. Direct effects occur on a building-by-building basis, and vary greatly depending on the location, size, and density of the trees. Indirect effects are those that change the surrounding environmental conditions, such as air temperature or humidity.The cooling effect of trees on ambient air temperature is an example of an indirect effect of trees. Indirect effects of trees are felt beyond the nearest building and can be aggregated over a large area, benefiting an entire neighborhood or even city.

Figure2-72.The benefits of urban forestry. Source: National Center of Excellence, Arizona State University.

Shading Urban Surfaces

Trees can be very effective in blocking the sun’s energy from reaching building facades and pavements.The amount of shading is dependant on species, which defines tree shape and density of foliage. For example, a broad leafed tree can block 95% of incoming radiation, but a deciduous tree will generally block less than 50% over the course of a year. It is important to understand which species will perform the best over time and during different seasons.

Shade from trees reduces cooling energy demand because it:

• prevents direct solar radiation from entering through windows;
• prevents walls, windows, and roofs from getting hot and transferring heat inside; and
• keeps the soil around a building cool, providing a “heat sink” for the building.

In fact, the shading from vegetation is more effective than Venetian blinds, tinting, or reflective coatings on glass for keeping building interiors cool. A study in Florida estimated that trees and shrubs planted near a residential home can reduce air condi- tioning costs by 40% (Parker 1983).The study showed that the most effective locations for trees were in front of windows and near the air conditioner. A 10% increase in air conditioner efficiency was observed when the unit was shaded.

Figure 2-73. Example of street shaded by a thick tree canopy. Photos courtesy of National Center of Excellence, Arizona State University.

While shading in the summer is extremely beneficial, shading during the winter can increase the heating demand in a home when shade prevents the sun from warming the building. A deciduous tree that loses its leaves in the winter will often allow 65% of the solar energy through to the house, which reduces this impact. Despite this fact, and given the mild winters of the Phoenix region, the benefits of shading in the summer far outweigh its drawbacks, as evidenced in Table 2-8.

Table 2-8 Simulated annual energy savings from trees for various metropolitan areas. All savings are in $/100 m2. Source:Taha et al. (1996)

Table 2-8. Simulated annual energy savings from trees for various metropolitan areas. All savings are in $/100. Source:Taha et al. (1996)

Figure 2-74. Combined indirect and direct effects on energy savings, using trees around a poorly nsulated residence.The results indicate that trees provide significantly greater economic benefit in Phoenix than in most other cities in the US. Data source:Taha et al. (1996).

Another affect of trees around a building is on wind speeds. While reducing winter wind speed is a proven benefit for colder regions, it has a negative effect during the summer. Winds that typically help to cool buildings during the summer are reduced by trees. However, the shading benefits are still more influential on energy use in a desert region, overall.

To fully appreciate the benefits of the direct effect of trees, it is important to consider both the positive and negative impacts that shading and wind shielding have on energy consumption in buildings. While actual energy savings depend on the design and efficiency of the buildings in question, in a study that used computer simulations to estimate the net effects for an older home (pre -1973) located in different climatic conditions, results showed energy savings for both cooling and heating in Phoenix. Phoenix may benefit more from trees than any other major city in the US.That finding alone is incentive to make trees a regular part of good energy policy in Phoenix.

Figure 2-75. Predicted temperature reductions for City of Phoenix from tree-coverage increases of 10% (equivalent to one tree added per house) and 25% (three trees per house). Source: Huang et al. (1987).

Cooling the Air

The most important indirect effect of trees is their ability to cool the air around them.This cooling phenomenon is the result of evapotranspiration, the process by which plants release

moisture as water vapor. Evapotranspiration uses up energy from solar radiation or warm air thus decreasing air temperature. Some large trees are known to transpire as much as 100 gallons a day

a cooling effect equivalent to running five air conditioners for 20 hours. A cooling effect of this magnitude can only be realized in a hot, arid climate, but not in humid climates where there is already a great deal of moisture in the air.

Evapotranspiration and shading are a powerful combination and can reduce air temperatures by 9ºF (5ºC) or more. In areas with mature trees, air temperatures during the day can be 3-6ºF (2-3.3ºC) lower than nearby, newer neighborhoods with less vegetation. Studies have shown that the cool air leaving tree canopies can rise to heights five times the height of the trees.The complex nature of heat and fluid transfer in urban areas makes modeling the effects of evapotranspiration difficult. Simulations developed at the LBNL and at ASU have been used to predict the temperature effects of changing the relative percentages and types of land cover in the Phoenix area (Bhardwaj 2006).The simulations predict that increasing the tree cover in Phoenix by 25% would result in a 10ºF decrease in daytime temperatures (Huang et al. 1987). Figure 2-75 shows the results from this simulation for a 24-hour period.

ImprovingAir Quality

Trees can improve the air quality in several, not so obvious ways. As trees have direct and indirect effects on energy use in buildings, so are there direct and indirect ways that trees help to improve air quality.The following list summarizes how trees improve air quality within urban environments.

Trees absorb green house gases such as carbon dioxide (CO2) for metabolic needs, and release oxygen (O2) as waste.

Particulate matter attaches to tree leaves through a process called dry deposition.This removes nitrogen oxides (NOx), sulfur oxides (SOx), particulate matter (PM), and ozone (O ) from the air.

Trees lower air temperature which in turn slows the chemical formation rate of ozone. Ozone is a major component of smog and is comprised of several ingredients:

• NOx – produced by high temperature vehicles and power plants
• VOCs – volatile organic compounds which evaporate from fuels

• Solar radiation – activates reactions; therefore, smog is a daytime phenomenon and can reach its peak in the afternoon when the solar flux is most pronounced.
• High temperatures – increases formation rate; the lower the temperature within urban areas, the less ozone is formed.

Trees reduce energy and electricity demand in buildings and cities.This in turn reduces emissions from power plants during peak hours. Fewer emissions mean less ozone and smog formation.

It is important to point out that VOCs are also a natural emission (biogenic) of photosynthesis and other metabolic reac- tions in plants. Forests are actually major sources of VOCs; however, these releases are neither as toxic to humans nor as difficult to break down. Isoprene and monoterpenes are two types of VOCs that contribute to ozone formation. Isoprenes are produced during the day, but in hot temperatures their release is greatly reduced. Most researchers agree that the beneficial effects of trees for reducing urban temperature outweigh the negative effects of VOC release.

Providing Natural Storm-Water Management

Vegetation is naturally designed to intercept falling raindrops and slow the descent of rainwater to the ground.This has a major influence on runoff, flooding, and erosion during times of intense rainfall. In areas dominated by impervious concrete, asphalt, and rooftops where this moderating effect is not present, fast flowing runoff can cut through unprotected soils, caus- ing soil erosion and water pollution in streams and waterways.The American Forestry Association estimates that a city with 30% tree coverage has over four times the amount of leaf surface area than the surface area of all paved and building surfaces combined.This can result in a significant reduction in peak flood flows, and thus reduce the need for constructed floodways and storm sewers, resulting in savings on construction costs for the city.

MentalandPhysicalBenefitsofVegetation

The link access to nature, positive human emotions, and feelings of relaxation have long been described by poets and naturalists. Recent studies have been able to empirically document these subjective assumptions through academic surveys and physiological monitoring systems. One study found that images of natural colors and landscapes produce more relaxed brainwave signals and positive survey responses than did images of urban settings (Ulrich 1981). Other studies have shown that workplaces that provide open outdoor spaces and areas where trees and vegetation are in view of employees show an increase in productivity and job satisfaction.

Trees can also reduce noise levels in urban areas.Their leaves, twigs, and branches break up and absorb the high frequency city sounds that can cause irritation for residents. A line of trees 100 feet long and 50 feet tall can reduce highway noise by about 50% (6 -10 decibels).The sound of leaves rustling in the wind and birds singing can also have a soothing effect on the observer

In addition to benefits to humans, trees and vegetation provide homes, protection, and food for urban wildlife.They can help restore or maintain the natural biodiversity that existed prior to heavy urban development.

Urban areas can create character and a sense of pride by incorporating trees unique to their climate and region.Trees placed along traffic corridors can also improve the image of the city to visitors and reduce the stress of drivers during their daily commutes.The proven benefit of trees and vegetation to the mental and physical health of citizens is a very important and often overlooked aspect of trees in urban areas.

Urban Forestry Strategies

Phoenix region urban heat island is largely caused by its lack of vegetation. What once was an area of bountiful desert bris- tling with Sonoran Desert shrubs and shade trees is now a mix of concrete, asphalt, walls, and roofs, with manicured vegeta- tion sprinkled about. Estimates indicate that tree canopy accounts for less than 13% of land cover in the developed areas of Phoenix.This lack of vegetation exposes pavements to the intense sun and greatly reduces evapotranspiration rates that would otherwise help to balance the net energy of the urban surface.This section of the guidebook offers urban forestry strategies that are appropriate for the region and provide the greatest benefit for reducing energy use and cooling the region as a whole The components of a citywide urban forestry program can be grouped into two categories, reforestation and conservation.

REFORESTATION

Reforestation is the restocking of areas depleted of vegetation with native tree stock. Urban reforestation is simply the act of maximizing the native vegetation coverage within a developed area. In order to develop a successful urban reforestation program, it is important to include the following components:

• Quantify and Monitor – Establish a baseline for the total number of trees currently in an area and track the number of trees planted and destroyed each year.This will help set citywide goals and provide the data necessary to verify

plan progress.

• Target Specific Areas – Identify locations that would benefit the most from increased tree coverage.

• Select Appropriate Species – Use only plants that are native to the region and provide the desired shading effect. This will save on water and maintenance

• Optimize Placement – Place trees to produce the greatest savings in energy and water use.

• Build Upon Successful Landscaping Practices – Integrate urban reforestation strategies into existing landscaping practices and policies if the community already encourages low water use, native plants.

Current Landscaping Activities in the Phoenix Region

The Phoenix region has historically benefited from an abundance of water availability for landscaping and irrigation. Most of this water originates from hundreds of miles away and its delivery to Phoenix is made possible by a series of manmade water- ways and political agreements that were established in the mid-twentieth century. However, with the rapid influx of popula- tion, construction, and expansion of city boundaries, many of the Valley’s water resources are beginning to be strained. While Phoenix, by many estimates, will likely have plenty of water to meet the demand for the next 100 years, other cities in Arizona may not be so fortunate. Gilbert,Tucson, Casa Grande, and Flagstaff are among those that have limited water supplies and are beginning to rethink the way that water is used by their residents. Since the late 1990s, many of these cities have organized educational campaigns and developed ordinances that address landscaping.They often mandate that all new developments must use xeric (low water) landscaping, and that areas such as golf courses and manmade lakes must use reclaimed water from wastewater treatment plants. In areas that have existing mesic (water intensive) landscaping, residents are encouraged to use more efficient irrigation techniques. A reforestation plan would build upon these practices and require quantification, track- ing, and maintenance.

To date, there has not been a thorough inventory of the urban forest in the Phoenix area. An initial study would establish a baseline for the city and would improve the accuracy of models used for predicting the benefits of increased canopy coverage within the city. Once a baseline is established, future planting and destruction should be monitored. A report documenting the status of the urban forest in Phoenix should become part of the City’s annual Sustainability Report.

Target Locations

Every building owner and citizen can benefit from the planting of new trees. However, a reforestation plan should target locations with the greatest potential for success and overall impact on the Valley.

Residential Property — Homes are by far the largest single land use category in the Phoenix region. If each homeowner planted one or more trees, the area’s urban forest would increase by over a million trees. Families are also likely to care for their own personal landscaping, which would reduce the financial burden of cities. Home owners also have the most to gain in terms of energy savings and property value increases. Strategies should seek to get homeowners and residential developers engaged and committed to future urban reforestation activities.

Commercial and Office Developments — Commercial properties make up the second largest land use category and offer a great opportunity for planting trees. Some property owners may reject the idea, while others will embrace it.Tenants usually prefer attractive landscaping and may be willing to pay more for space with a large tree population.

Public Properties — Government offices, schools, highways, bus stops, streets, and other easements are among the many forms of public properties. Working with the Arizona Department of Transportation, cities can specify that trees be included along major streets and highways. Long term strategies are needed to ensure the success and expansion of tree planting on public grounds.

Encouraging tree planting will be most effective if each type of location is targeted with unique methods and strategies. Dif- ferent incentives, ordinances, and educational efforts may be effective depending on the type of property to be landscaped

Tree Planting in a Hot, Arid Climate Region

Planting trees in a hot, arid climate region can have an immediate positive effect on the urban climate.The cooling effect of vegetation can actually create microclimates in which urbanized areas are cooler during the day than the surrounding desert areas.This is commonly referred to as the “oasis effect.”The Phoenix region has small pockets and corridors that experience this phenomenon. Those areas are usually heavily watered parks, golf courses or greenbelts, and comprise a small percent- age of the entire developed area.These “oasis” areas do experience cooler air temperatures day and night but require large amounts of water, a resource that our region cannot afford to waste. In addition to their water hungry habits, golf courses require continual maintenance and do not directly help to reduce energy demand in buildings.

Planting trees and other vegetation in a hot, arid climate requires knowledge of the appropriate species and optimal planting locations that maximize benefits while minimizing maintenance.

Selecting the Best Plants for the Phoenix Region

A healthy urban forest must be diverse and consist of plant species that are native or adapted to the regional climate and ecosystems. Water is a limited resource in nearly all areas of the United States and especially in the Southwest. Water can be the primary expense of maintaining a landscape. In fact, the savings in air conditioning costs that large, deciduous trees and grass yards provide can be counteracted by expensive summer water bills.Through the careful selection of plants, the amount of moisture needed to support an urban forest can be greatly reduced. Plants convert minerals and water into nutrients through photosynthesis.This requires plants to absorb water through their roots and transfer it throughout their systems When leaves get hot, they transpire moisture through their leaves. Plants native to hot dry regions have evolved methods to reduce water loss from their leaves. Some of these plants use small leaves to prevent moisture loss, while others have leaves that are covered with a waxy or felt-like coating. Additional differences in the cellular and internal structure configurations help drought tolerant plants to survive in harsh desert environs

Xeriscaping is a landscaping practice that minimizes the amount of water required to support plant life. Xeriscaping (derived by combining the Greek work for “dry,” xeri, with “landscape”) has become popular among gardeners, landscapers, and urban planners seeking sustainable approaches to planting in a desert climate. Water conservation is important to the long term sus- tainability of the Phoenix region, and xeriscaping programs have been developed in many cities to encourage property own- ers to landscape with drought tolerant plants. Some might believe that xeriscaping greatly restricts the variety and freedom needed to create attractive and interesting landscapes, but the opposite is true.There are thousands of drought tolerant trees, shrubs, vines, and groundcovers that require little water while providing beauty and diversity in the landscape., In his book, Landscaping with Native Plants of the Southwest, George Oxford Miller recommends the following plants for dry climates.

Please refer to the book for more details about and pictures of these and other native desert plants

TREES

Acacia farnesiana, huisache Acacia greggii, catclaw acacia

Arbutus arizonica, Arizona madrone

Celtis laevigata var: reticulate, netleaf hackberry Cercis canadensis var. mexicana, Mexican redbud Chilopsis linearis, desert willow

Cupressusarizonica, Arizona cypress Ebenopsis ebano, Texas ebony Fraxinus cuspidate, fragrant ash Fraxinus greggii, Gregg ash

Fraxinus velutina, Arizona ash Juglans major, Arizona walnut Juglans microcarpa, little walnut Juniperus species, junipers

Leucaena retusa, goldenball leadtree Olneya tesota, desert ironwood Parkinsonia florida, blue palo verde

Parkinsonia hybrid, Desert Museum palo verde

Parkinsonia microphylla, foothills palo verde Pinus edulis, New Mexico pinyon pine Prosopis glandulosa, mesquite

Prosopis velutina,velvet mesquite

Prunus serotina var. rufula and var. virens, southwestern black cherry Quercus arizonica, Arizona white oak

Quercus emoryi, Emory oak Quercus grisea, gray oak

Quercus hypoleucoides, silverleaf oak Quercus oblongifolia, Mexican blue oak Quercus pungens, sandpaper oak Quercus turbinella, shrub live oak

Rhus lanceolata, prairie flameleaf sumac Robinia neomexicana, New Mexico locust

Sambucusnigrasubsp.canadensis,Mexican elder Sapindus saponana, soapberry

Ungnadia speciosa, Mexican buckeye

SHRUBS

Acacia constricta, white-thorn acacia Agave species, century plants Aloysis gratissima, bee brush Amorphia fruticosa, false indigo

Anisacanthus quadrifidus var. wrightii, flame anisacanthus Anisacanthus thurberi, desert honeysuckle

Artemisia filifolia, sand sagebrush Artemisia tridentata, big sagebrush Baccharis sarothroides, desert broom Bouvardia ternifolia, scarlet bouvardia Buddleja marrubifolia, woolly butterflybush Caesalpinia gilliesii, desert bird of paradise Calliandra conferta, fairy duster Ceanothus greggii, desert ceanothus

Celtis pallida, desert hackberry

Cercocarpus montanus, mountain mahogany Choisya dumosa, starleaf Mexican orange Chrysactinia mexicana, damianita

Dalea Formosa, feather dalea Dalea frutescens, black dalea Dasylirion species, sotols Dononaea viscosa, hopbush

Echinocereus species, hedgehog cacti Encelia farinosa, brittle bush Ephedra species, joint firs

Ericameria laricifolia, larchleaf goldenweed Ericameria nauseosa, chamisa

Fallugia paradoxa, Apache plume Fendlera rupicola, cliff fendlerbush Ferocactus species, barrel cacti

Foresteria pubescens var. pubescens, desert olive

Fouquieria splendens, ocotillo Garrya wrightii, silktassel Hesperaloe parviflora, red yucca Justicia californica, chuparosa Justicia canadicans, jacobinia Krascheninnikovia lanata, winterfat Larrea tridentata, creosote bush

Leucophyllum frutescens, Texas ranger Lycium species, wolfberry

Mahonia species, barberries Mamillaria vivipara, pincushion cactus Mimosa dysocarpa, velvet pod mimosa Nolina species, beargrass

Opuntia species, cholla or prickly pear Pachycereus schottii, senita cactus Parthenium argentatum, guayule Parthenium incanum, mariola Psorothamnus scoparius, broom dalea Purshia stansburiana, Mexican cliffrose Rhus microphylla, little-leaf sumac Rhus virens, evergreen sumac

Salvia greggii, autumn sage Senna wislizeni, shrubby senna Simmondsia chinesis, jojoba

Sophorasecundiflora,Texasmountain laurel Stenocereus therberi, organ-pipe cactus Tecoma stans, yellow trumpet flower Vauquelinia californica, Arizona rosewood Viguiera stenoloba, skeleton-leaf goldeneye Yucca species

VINES

Campsis radicans, trumpet creeper Clematis ligusticifolia, western virgin’s bower Maurandya antirrhiniflora, snapdragon vine Parthenocissus quinquefolia, thicket creeper

GROUNDCOVERS

Artemisia ludoviciana, white sagebrush Dalea greggii, Gregg dalea

Glandularia goodingii, Goodding’s verbena Muhlenbergia rigens, deer grass

Phyla species, frogfruit Sedum species, stonecrop

Shading for Buildings and Occupants

The building envelope, consisting of the roof, walls, doors, and windows, provides a buffer between the outdoors and the interior environment.Vegetation can act as an additional buffer, reducing the energy required to maintain comfortable temper- atures within a climate controlled building.Trees, shrubs, vines, and groundcovers form a protective shell around these surfaces, preventing direct sunlight and reflected heat from reaching the building’s façade and transferring heat through the wall.The shade and increased humidity from plants also reduce air temperature during the summer and provide protection from cold winds in winter

The natural cycle of deciduous trees make them a perfect choice for both summer and winter energy savings. During the spring and summer when the sun’s intensity is at its peak, the leaves of trees are fully spread, capturing the sun’s energy and converting it into nourishing food for growth and reproduction.These leaves often block over 80% of incoming energy.This results in natural shading that also allows rising warm air to pass into the ambient air, maintaining a cool, dark area underneath the tree. In winter, plants begin to slow their metabolism in preparation for shorter days and limited sunlight. Deciduous trees practice the survival mechanism of shedding their leaves when the temperature drops.The once deep leaf shade becomes

a series of branches, allowing the winter sun to penetrate and warm the building.This natural cycle is automatic, providing a benefit year round. Even evergreens can be a benefit year round, providing shade in the summer and blocking chilly winds in the winter

Figure 2-76. Looking up from under a mesquite tree during summer. Photo courtesy of National Center of Excellence, Arizona State University.

Placing a tree in the correct location will greatly improve its ability to decrease energy demand.The first priority is to shade windows to prevent direct sunlight from entering the building. Forty percent of building solar heat gain is through windows, and conventional blinds on the inside do not prevent this. By placing a tree, tall shrub, vine covered trellis, or arbor in front of windows, building owners can block direct sunlight while providing privacy and allowing in soft light. Using vegetation in front of windows will also help to cool the air coming in when windows are open.

The exterior walls on a building are vulnerable to heat penetration no matter how well they are insulated.This added heat forces the air conditioning system to compensate, resulting in increased utility bills and decreased equipment lifetime.The summer sun attacks the east wall in the morning, the south wall nearly all day, and the west wall in the afternoon. Walls can be shaded by trees planted about 15-20 feet away.The optimal location for trees is on the west side of a building.To shade exte- riors while still allowing air circulation around the building, be sure to choose trees that do not have low hanging limbs. Native trees such as the walnut, ironwood, New Mexico locust, and huisache are recommended by George Miller as substitutes for the traditional ashes, maples, and oaks. Of course, a mature tree will provide greater benefit than a young one. For this reason it is important to emphasize the need to conserve existing trees. If more light is desired, a tree such as the desert willow, mes- quite, or palo verde let light through while blocking the majority of solar radiation. Walls can also be shielded by vines climbing on trellises or arbors clinging directly to a masonry wall.There is some risk of the vines penetrating roof shingles or mortar, which can cause deterioration and expensive damage to the building exterior. A trellis or arbor with climbing vines set off of the wall acts to block the sun’s rays while creating an air space that resists the transfer of heat to the building.

The roof of a building, if shaded by a large tree, can reduce the interior building temperature by eight to ten degrees. Often, air conditioning units are placed on roofs or alongside houses in direct sunlight. Providing shade for an air conditioning unit can increase its efficiency dramatically.

Figure 2-77. Examples of vines, trees, and groundcover helping to prevent solar heat gain in buildings.

Courtesy of National Center of Excellence at Arizona State University

Paved driveways, patios, and rock gardens reflect the sun’s rays and emit heat energy, which can heat building facades and make outdoor areas around a building uncomfortable. Small shrubs and groundcover help to prevent the heating of landscape rock, similar to what occurs in the natural desert. Patios and driveways should be shaded with tall shrubs, arbors, or shade trees to mitigate build up of stored heat. Air temperature above different groundcovers can be up to fifteen degrees cooler than air temperature at the same height above rock or paved surfaces (Miller 2007).

The Arizona State Energy Code and local government landscape ordinances should be changed to encourage use of trees and other shading devices to reduce energy use in buildings and mitigate the urban heat island. For example, Los Angeles’ Landscape Ordinance No. 170, 978 states that, “A minimum of one tree, or equivalent, shall be required per each 25 feet of exposure.”

Shading Pavements and Hardscapes

Exposed pavements and hardscapes absorb solar radiation during the day, reaching temperatures of over 160ºF in some cas- es.The heat energy is then released slowly to the night sky, resulting in elevated nighttime air temperatures, especially around extensively paved areas such as parking lots, airports, and highways. Shade trees can provide a first line of defense against the sun by protecting paved surfaces from direct sunlight.

Trees placed along roads and parking lots provide benefits that complement pavement structure.These benefits include capturing runoff and improving water quality through natural infiltration. Planting shade trees along sidewalks and within park- ing lots can improve the comfort level of those using the areas. Shade trees can also enhance the appearance of buildings and thus increase their desirability and property value

Optimal Planting Locations for Building Energy Use and UHI Mitigation

• Plant shade trees, tall shrubs, vine trellises, or arbors near the south, west, and southwestern corners of buildings.
• Shade windows to block direct sunlight from entering the building.
• Shade air conditioning units to improve efficiency.

• Use shrubs and groundcover plants to prevent solar energy from heating up landscaping rocks that can reflect or emit radiation and increase the thermal loads of buildings.
• Plant shade trees next to the street or between the sidewalk and the street

• Plant trees in parking lots to shade pavements and cars.

CONSERVATION

Conservation forestry refers to the protection of existing trees in and around developed areas. Millions of dollars could be saved every year if fewer trees and native vegetation were destroyed during development and land transactions. Phoenix does not have a tree conservation program, although many cities have tree ordinances to protect street trees, historic trees and even some trees on private property. While these are very important conservation measures, the majority of vegetation loss in the Phoenix region occurs at its fringes where new developments replaces native desert and agricultural land. A com- mon practice in Maricopa County is to completely clear and grade land prior to development.This also occurs when land is improved for sale. Developers will argue that this type of practice is more economical and the savings are passed on to the future property owner. While this may be true in terms of dollars, the hidden economic and environmental costs resulting from the loss of vegetation, permeability, biodiversity, and connection to the natural environment should be considered. Recent trends in luxury home communities in northern Scottsdale indicate that owners appreciate the natural beauty of the Sonoran Desert and will pay more to live in communities that are integrated with native desert. When vegetation loss or cannot be avoided, ordinances must require that reforestation efforts replace a large percentage of plants following the clearing and development process.

Education also plays an important role in forest conservation. Governmental planning departments, professional trade orga- nizations, and conservation groups can provide instructional seminars and literature to land clearing contractors and develop- ers about low impact methods that minimize the destruction of native desert vegetation during land development.

Making Urban Forestry a Priority in the Valley

Many cities around the country, including Sacramento, Chicago, Houston, San Francisco, and Austin, have adopted aggres- sive, citywide reforestation plans to ensure the future of trees and vegetation in their cities. It is time that the government and citizens of the Phoenix region begin to consider the importance of trees in urban areas

A successful urban reforestation plan requires the involvement and cooperation of several groups within the community. Newly planted trees must be properly maintained and watered for the first two to three years in order for the tree to survive to become self sufficient. City and county governments are typically unable to take on major new tree maintenance programs due to competing budgetary priorities. Similarly, local botanical, nonprofit organizations can offer only limited volunteer time and funding to provide the necessary care and maintenance.That is why it very important to find ways to involve businesses and homeowners. Property owners must be made aware of the many financial benefits of tree planting, including increased property values, decreased energy use, increased outdoor shade, and the general enjoyment of their property.The value of trees varies according to personal preferences; however, the environmental and economic values may be the most persuasive for motivating increased urban reforestation in the region. A study conducted by American Forests in 2001 developed a rough estimate of the economic value of trees.The Houston Advanced Research Center used the estimate to project the return on investment per tree.They estimated an 11.4% return on investment for their reforestation plan. While this estimate may uncer- tain, it is safe to assume that the energy savings benefit per tree would be greater in the Phoenix region

The Center for Urban Forest Research, a part of the USDA Forest Service, conducted a similar analysis of the benefits of trees in the Southwest.They published their findings in the “Desert Southwest Community Tree Guide.”The results of their quantitative study show that the combined average economic benefit increases as a tree matures.

Table 2-9. Estimated annual economic benefit per tree in the southwest US. Based on the combined savings from pollution, erosion control, shading, and air cooling effects of trees, as presented by the USDA Center for Urban Forest Research. Source: McPherson 2004

Partnerships, Initiatives, and Education

Planting millions of new trees in an urbanized region requires a considerable amount of effort and coordination of resources. To accomplish the actions and strategies discussed earlier will require a multitude of new partnerships, initiatives, and educa- tion efforts

New partnerships between public and private organizations can result in new business growth that contributes to the eco- nomic health of the region. One example of this type of partnership involves the supply of appropriate trees.The quantity of trees that would be needed for a massive urban forestry program may far exceed the capacity of existing nurseries to provide. An entrepreneurial approach to this supply chain dilemma could be the solution to such a shortage of trees, or an integrated effort within the network of Maricopa County nurseries could solve the problem.

Sources of funding could also come from public organizations such as water, electricity, gas, and municipal utilities. As part of energy conservation programs and peak load reduction, utilities such as APS and SRP could offer incentives or offsets for building owners who plant additional trees in strategic locations on their properties to reduce cooling demand and shade pavements

Regional tree initiatives led by advocacy groups, nonprofit organizations, local foundations, and governmental organizations are also needed.These advocates could promote tree planting and maintenance activities to the top of their local government agendas, devise new ways to achieve tree anting goals, and create educational and outreach events. Experienced organizations could assist by providing leadership and coordination for managing private and public funds.

Educational programs, materials, and events will be needed to involve the community and to develop generational con- nections between children, their parents, and grandparents. Some reforestation plans suggest developing regional seedling distribution programs for elementary schools to teach children about tree planting, tree care, and other basics that will follow them throughout their lives.

StepsTowards Implementation

• Create an inventory of all trees in the Phoenix region, characterized by land use, location, type, and age, if possible.

• Change the energy code to include specific provisions for shade trees.

• Encourage expanded public policies for trees.

• Lower tree prices and increase availability of native and desert adapted trees within the region.

• Institute a Regional Trees Initiative that includes tree advocates, homeowners, businesses, and schoolchildren.

• Implement a targeted program for office and retail development.

• Expand landscape set -asides for local, state, and federal roadway projects.

• Institute tree incentives and programs for parking area improvements.

• Expand private and public support for existing tree organizations.

• Create a Regional Tree Conservation Partnership of major public conservation agencies, aimed at outlying and developing areas and tree conservation on private lands.

• Target education, training, and awareness programs to large tract property owners, construction contractors, and land clearing companies and staff.

• Enlist regional leadership, particularly in outlying counties, from among elected officials and community leaders, to support tree protection and conservation.

• Create and fund a public-private partnership to expand the tree market in the region and tree planting activities in the private sector.

Adapted from HARC (2004)

Further Information about Urban Forestry in the Phoenix Region

Phoenix Urban Forestry, City of Phoenix Parks and Recreation Department.,

802 W Encanto Blvd., Phoenix, AZ 85007. (602) 495-3763; www.phoenix.gov/FORESTRY/#URBAN

Arizona Community Tree Council, John Eisenhower, President,

110 W Washington St., #100, Phoenix, AZ 85007. (602)-542-6191; www.aztrees.org

Arizona State Land Department Ron Romatzke, Urban Forester,

616 W Adams, Phoenix, AZ 85007. (602) 542-2518; www.land.state.az.us/programs/natural

University of Arizona Cooperative Extension Service,

4341 E Broadway, Phoenix, AZ 85040. (602) 470-8086; ag.arizona.edu/maricopa/garden/

The National Arbor Day Foundation,

00 Arbor Ave., Nebraska City, NE 68410. www.arborday.org Treetures 1-800-863-7175; www.treetures.com

National Tree Trust,

120 G St., NW, Suite 770, Washington, D.C. 20005. 1-800-846-8733

International Society of Arboriculture, P.O. Box 3129, Champaign, IL 61826-3129. www.isa-arbor.com

U.S. Environmental Protection Agency (EPA) on Urban Heat Island

http://www.epa.gov/heatisland/

National Center of Excellence on SMART Innovations for Urban Climate + Energy

Arizona State University http://asusmart.com/urbanclimate.php

Cool Roof Rating Council (CRRC)

http://www.coolroofs.org/

Lawrence Berkeley National Laboratory (LBNL) Urban Heat Island Group

http://eetd.lbl.gov/HeatIsland/

NASA Earth Observatory:The Earth’s Big Cities, Urban Heat Islands

http://eobglossary.gsfc.nasa.gov/Study/GreenRoof/index.htm

American Concrete Paving Association (ACPA)

http://www.cement.org http://www.pavement.com/chaplinks/chapters/chapmap.html).

National Asphalt Paving Association http://www.hotmix.org http://www.hotmix.org/view_article. php?ID=63

Asphalt Paving Alliance

http://www.asphaltalliance.com/

The Portland Cement Association

http://www.pavement.com

FHWA’s Office of Pavement Technology

http://www.fhwa.dot.gov/pavement/ about.htm

FHWA’s Office of Planning, Environment, and Realty

http://www.fhwa.dot.gov/hep/index.htm

AASHTO Center for Environmental Excellence

Home

Consortium for the Study of Rapidly Urbanizing Regions, Arizona State University

http://ces.asu.edu/csrur/index.htm

Houston Advanced Research Council (HARC)

http://www.harc.edu/harc/Projects/CoolHouston/HeatIsland

References

Akbari, H., Rose, L. and Taha, H. (1999). “Characterizing the Fabric of the Urban Environment: A case study of Sacramento, California.” Lawrence Berkeley National Laboratory, US Department of Energy. LBNL-44688.

Asaeda T.,Vu,T.C., Wake, A. (1996) “Heat storage of pavement and its effect on the lower atmosphere. ” Atmospheric Env., 30 (3): 413

Belshe, M., Kaloush, K., Golden, J., Phelan, P. (2007). “AR-ACFC Overlays as a Pavement Preservation Strategy for PCCP”. Jour- nal of the Transportation Research Board, CD-ROM, Washington, D.C., January 2007 – National Academies Press.

Bhardwaj, R., Phelan, P.E., Golden, J., Kaloush, K. (2006). An Urban Energy Balance for the Phoenix, Arizona, USA Metropolitan Area. Proceedings of 2006 ASME International Mechanical Engineering Congress and Exposition. November 5-10, 2006, Chi- cago, Illinois, USA

Brantley, L. and Brantley, R. (1996). Construction Materials. In Frederick, M., Loftin, M., and Ricketts, J., editors, Standard Hand- book for Civil Engineers. McGraw-Hill. New York. 5.2, 5.9, 5.6

Brazel, A., Selover, N.,Vose, R. & Heiser, G. (2000). “The Tale of Two Climates-Baltimore and Phoenix Urban LTER Sites.” Climate Res., 15, 123-135

Brazel, A. J., Gober, P., Lee, S., Grossman-Clarke, S., Zehnder, J. and Hedquist, B. (2007) Dynamics and determinants of urban heat island change (1990-2004) with Phoenix, Arizona USA. Climate Research 33:2 , pp. 171-182.

Bureau of Transportation Statistics (2006).

California Department of Transportation 2003. “I-15 Devore Project.” <http://www.dot.ca.gov/dist8/i15devore/ project%20photos/I-15Devore_project_photos.htm> (November 15th, 2005)

Carlson, J. (2006). Quantifying the diurnal thermal variability of urban surface pavements in a hot climate region.Thesis (M.S.) Arizona State University

Çengel,Y. (2003). Heat Transfer; A Practical Approach, Second Edition. McGraw Hill, Boston, pp. 563-569.

Celestian, S. and Martin, C. (2003). “Leaf physiology of four landscape trees in response to commercial parking lot location.” Central Arizona Phoenix – Long Term Ecological Research. NSF.

Florida Solar Energy Center, < http://www.fsec.ucf.edu/> Accessed August, 2007.

Golden, J. (2004). “The Built Environment Induced Urban-Heat-Island Effect in Rapidly Urbanizing Arid Regions – A Sustainable Urban Engineering Complexity.” Environmental Sciences, 2003/2004,Vol. 1, No. 4, pp. 321–349

Golden, J., Carlson, J., Kaloush, K., Phelan, P. (2007). “A comparative study of the thermal and radiative impacts of photovoltaic canopies on pavement surface temperatures.” Solar Energy, 81 (7) 872-883

Gui, J., Phelan, P., Kaloush, K., Golden, J. (2007). “Impact of Pavement Thermophysical Properties on Surface Temperatures.” ASCE Journal of Materials in Civil Engineering.,Volume 19, Issue 8, pp. 683-690

Hitchcock, D. (2004). “Cool Houston! A Plan for Cooling the Region.” Houston Advanced Research Center (HARC),The Woodlands,Texas

Houston Advanced Research Center (HARC) < http://www.harc.edu/>

Huang,Y.J., H. Akbari, and H.G.Taha, and A.H. Rosenfeld. (1986). “The Potential of Vegetation in Reducing Summer Cooling Loads in Residential Buildings.” LBL Report 21291, Berkeley, CA: Lawrence Berkeley Laboratory

Incropera, F. and D. DeWitt, (1996). Fundamental of Heat and Mass Transfer; Fourth Edition. John Wiley and Sons. LBNL (Lawrence Berkeley National Laboratory). Urban Heat Island Group. <http://eetd.lbl.gov/HeatIsland/>

Levinson, R. and H. Akbari,(2001) “Effects of Composition and Exposure on the Solar Reflectance of Portland Cement Con- crete,” Heat Island Group, Lawrence Berkeley National Laboratory.

Konopaki, S., Akbari, H., (2002). Energy savings for heat-island reduction strategies in Chicago and Houston. LBNL-49638

McPherson, G., Simpson, J., Peper, P., Maco, S., Xiao, Q., & Mulrean, E., (2004). Desert Southwest Community Trees Guide: “Ben- efits, Costs, and Strategic Planting.” Center for Urban Forest Research.

McMichael, A.J., Butler, C., & Ahern, M.J. (2002). “Environment as a global public good for health.” In R. Beaglehole, N. Drager, &

R. Smith (Eds.), Global public goods for health, World Health Organization and United Nations Development Programme Col- laboration. Oxford: Oxford University Press.

Miller, G. O. (2007) Landscaping with native plants of the Southwest.Voyageur Press.

NRCA (2005). National Roofing Contractors Association <http://www.nrca.net/> November 2007

Parker, J. H. (1983). Landscaping to Reduce the Energy Used in Cooling Buildings. Journal of Forestry 81(2):82-83

Pomerantz, M., Pon, B., Akbari, H., S.C. Chang (2000) The Effect of Pavement Temperatures on Air Temperatures in Large Cities. LBNL-43442

Roberts, S.,T.R. Oke, J.A Voogt, C.S.B., Grimmond, and A. Lemonsu (2003). “Energy Storage in a European City Center.” Fifth International Conference on Urban Climate, September, 2003 – geo.uni.lodz.pl

Rose, S.L., Akbari, H., and H.Taha. (2003). “Characterizing the Fabric of Urban Environment: A case study of Metropolitan Houston,Texas”. Lawrence Berkeley National Laboratory report LBNL-51448.

Rosenfeld, A., H. Akbari, S. Bretz, B. Fishman, D. Kurn, D. Sailor, & H.Taha (1995). “Mitigation of urban heat islands: materials, utility programs, updates.” Energy and Buildings, 22 (3), pp. 255-265

Rosenfeld, A.H. Akbari, J.J. Romm, M. Pomerantz, “Cool Communities: Strategies for Heat Island Mitigation and Smog Reduction,” Energy and Buildings 28 (1998) pp. 51-62

Sailor, D., L. Kalkstein and E. Wong (2002) The Potential of Urban Heat Island Mitigation to Alleviate Heat-Related Mortality:

Methodological Overview and Preliminary Modeling Results for Philidelphia, Fourth Symposium on the Urban Environment May 20, 2002.

Seattle Municipal Civic Center Master Plan 1999. Solar Access Study < http://www.seattle.gov/fleetsfacilities/civiccenter/master- plan/default.htm> Accessed: October 2007

Somayaji, S. (2001). Civil Engineering Materials, Second Edition. Prentice Hall. New Jersey. pp. 52, 383, 449.

Stefanov, W., Ramsey, M. and Christensen, P. (2001). Monitoring urban land cover change: An expert system approach to land cover classification of semiarid to arid urban centers. Remote Sensing of Environment. 77, 173-185

Taha, H. 1996. Modeling the impacts of increased urban vegetation on the ozone air quality in the South Coast Air Basin. Atms. Environ., 30, 3434-3430

Taha, H. (1997). “Urban climates and heat islands; albedo, evapotranspiration, and anthropogenic heat”. Energy and the Environ- ment, 25 (2), pp. 99-103

Ulrich, R.S. 1981. “Natural Versus Urban Scenes: Some: Psychophysiological Effects.” Environment and Behavior. 13:53-556

US Environmental Protection Agency “Cooling our Communities: A Guidebook on Tree Planting and Light-Colored Surfacing,”, January 1992, 22P-2001

US Army Corps of Engineers, (2000). Hot-Mix Asphalt Paving. Library of Congress catalog card number LC 00-135314. Fed- eral Aviation Administration, AC 150/5370-14A, pp. 3, 5, 125.

Ziedman, K. (2005) “Roadway Reflectivity and Visibility.” Report prepared for Granit Rock Company, Watsonville, CA.

Chapter 3:

Design for Climate and Energy

Chapter 3: Design Strategies for Climate and Energy

Chapter 3 Table of Contents

Introduction • 133

Types of Buildings • 134

Evaluating the Environmental Impact of Buildings • 135 Fundamentals of Sustainable Building Design • 135

TechnicalStrategies • 140

Site Selection and Design • 141 Passive Solar Design • 148

Mechanical and Electrical Systems • 156

BuildingLighting,Equipment,EnergyManagement,andUtilities•161Water Management and Conservation • 165

Materials and Product Selection • 167 Additional Resources • 172 References • 172

3

Introduction

Buildings and their support systems are the centerpiece of urban life.They shelter us from the harsh natural elements, provide access to water and food, power our appliances, provide light after the sun goes down, collect and dispose of our wastes, and offer privacy and sense of personal safety. We sleep, eat, bathe, work and play within them. Their location determines the length of our daily commutes, and depending on their organization and functional diversity, they can either induce or hinder human interaction and a sense of community.Their facades create a city’s visual character and serve as major landmarks for visitors and tourists.They also depend on us for regular maintenance; forming a unique relationship between humans and the built environment.

The average American spends over 90% of their lives indoors and yet we are often unaware of the energy and resources used in the construction and operation of buildings. Buildings form a large portion of the total environmental impact in the United States. Even though they only contribute to 12% of land use, buildings demand a significant amount of natural resources, generate solid and liquid wastes and are responsible for nearly half of the atmospheric emissions released in the United States. Their contribution to the economy is also very important. According to the Department of Energy’s Building Energy Databook the construction market for commercial, residential and industrial buildings comprises 14.2% of the $10 trillion U.S. GDP.

There are many different types of buildings in an urban area, each having different program requirements and energy use patterns.

A building’s energy consumption is the largest portion of its environmental impact (Levin 1997). 42% of the U.S. energy consumption and 68% of its electricity is consumed in buildings every year (WBDG 2005). Over the past two decades many improvements to energy efficiency have been incorporated into new buildings. However, according to the US energy information agency, a large majority of the existing buildings that are more than a decade old do not meet current energy efficiency construction standards (EIA 1991). It is necessary to perform energy analysis of existing buildings to determine if energy retrofits or improvements are necessary. Investing to improve the energy efficiency of buildings can provide immediate and relatively predictable cost savings resulting from lower energy bills (Krarti 2000). This section of the guidebook will take a closer look at many of the strategies that can be incorporated into new and existing structures that can reduce energy, water and material use in buildings with particular attention to solutions for the Phoenix regional climate.

Types of Buildings

Buildings are generally grouped into three major categories; residential, commercial and industrial.The categories are based on the predominate activities that occur within them.

Residentia

Residential buildings are structures in which humans live and are often referred to as houses. Housing can support the needs of a single family or provide shelter and living space for thousands of people. They can range in size from one- room wood-framed, masonry, or adobe dwellings to multi- million dollar sky scrapers. Three story residential buildings are considered low-rise while anything larger is classified as high-rise. The majority of housing in the Phoenix area is low-rise though recent trends have seen a growing number of high-rise residential structures as the population growth continues to drive demand

Residential permits per 10,000 residents in the Phoenix and Arizona from 1996 to 2006. Source: National Association of Home Builders

Commercial

Commercial buildings provide shelter for business establishments and other organizations that provide services. This includes traditional service businesses, such as retail and wholesale stores, hotels, restaurants, offices and hospitals. It also includes institutional facilities such as public schools, correctional facilities, and religious and fraternal organizations. Commercial buildings are generally

owned by corporations or investments institutions and have the greatest potential for adopting and benefiting from high-

performance strategies. The majority of LEEDTM   certified

buildings in the U.S. are commercial buildings.The graph below indicates office and mercantile buildings consume the greatest amount of primary energy of all the commercial buildings.

Primary energy consumption by major commercial building type in the U.S. in 2003. Source: Energy Information Agency.

ndustria

Industrial buildings are those that provide for the goods- producing industries including manufacturing, agriculture, mining, forestry, fisheries, and construction. Industrial buildings generally consume more energy, water and raw materials than most buildings due to the demands of large industrial equipment such as motors, presses, conveyors, ovens, compressors and pumps. Industrial buildings also have unusual schedules sometimes having several worker shifts a day requiring the building systems to operate nearly 24 hours a day.

Evaluating the Environmental Impact of Buildings

The recent sustainable development movement has been gaining strength and evolving for nearly two decades.This has resulted in significant shift in the planning and delivery of buildings that include alternatives to the energy and resource hungry methods of past generations. A major turning point in the United States was the founding of the U.S. Green Building Council (USGBC) n 993 which brought about a newfound commitment to high-performance building practices within government and the building industry. For five years the USGBC task force developed a standard to evaluate a building’s resource efficiency and environmental impact.This standard, released in 1998, was aptly named Leadership in Energy and Environmental Design (LEED), and helped to remove ambiguity in the loosely interpreted concepts associated with sustainability and green building at the time. LEEDTM gained wide acceptance in both the private and public sectors causing an exponential shift in the construction industry in U.S. Since 1998, the number of LEEDT   certified new buildings has doubled every year resulting in 121 buildings in 2004 and over 694 in 2006. At this rate, within 10 years, the majority of new construction will be in high-performance and green buildings. While these numbers represent LEEDT for New Construction (LEED-NC), the USGBC has also released LEEDTM standards that address Existing Buildings (EB), Commercial Interiors (CI), a building’s Core and Shell (CS), Homes (H) and most recently Neighborhood Development (ND).    Although other building assessment standards do exist, LEEDT is now the most widely accepted standard and

The Arizona Biodesign Institute at Arizona State University’s Tempe Campus is the first building in Arizona to achieve LEEDTM Platinum Certification for new construction predominates the U.S. Other countries including Spain, Canada, and China are considering adopting LEED-based approaches to green building.The wide acceptance of LEEDTM can be attributed to the consensus based method employed by its authors when developing the standard often involving the collective minds of hundreds of design and construction professionals from all sectors of the building industry.

This section provides a general overview of sustainable design as it applies to buildings. There is no intention to circumvent the LEED M Rating System as they offer a level of detail that is out of the scope of this guidebook. It is our intention to provide a concise and general introduction to buildings types, core principles and benefits of high-performance buildings, the accepted design strategies for achieving improved performance and several additional resources for further reading. Particular attention is given to the strategies that are of most importance to the Phoenix region, including passive solar design, building envelope and water use and conservation

Fundamentals of Sustainable Building Design

Principles

Design, can been summarized as “the intentional shaping of matter, energy, and process to meet a perceived end or desire” (S. Ryn and S. Cowan 1995). Following the Industrial Revolution, the built environment has lacked the diversity and creativity of the natural landscape that which is replaces. The buildings were built with the sole purpose of functioning to meet a human centered need and often conforming to simple models and templates that were replicated regardless of the climatic and cultural differences between locations. Human-designed and engineered landscapes consisting of unrecyclable and toxic products produced by wasteful industrial processes replaced the natural landscape that once existed.This human-centric design paradigm greatly improved the quality of life for many however it neglected the fragility of natural resources and the associated impacts to human and ecological systems resulting in many of the environmental problems that our society faces today. The concept of ‘ecological design’ also referred to as ‘green’ design seeks to amend this disconnect between urban design and nature. Instead of urban designs that destroy the native landscape, designers would develop solutions that allow human-created structures to coexist in a symbiotic way with the native landscape. This can be achieved through designs that mimic the behavior of natural systems and are harmless in their production, use and disposal. This design ideal faces many barriers due to the legacy of infrastructure, products and process that have been created and ingrained into society over the past century

Sustainable Design broadens the scope of ‘green’ design and extends it to address the Triple Bottom Line: environmental impacts, social consequences and economic performance.The Conseil International du Batiment (CIB), an international construction research agency, defined the goal of sustainable design and construction in 1994 as “creating and operating a healthy built environment based on resource efficiency and ecological design.” CIB developed these Seven Principles of Sustainable Design and Construction;

1. Reduce Resource Consumption

2. Reuse Resources

3. Use Recyclable Resources

4. Protect Natural Systems

5. Eliminate Toxics

6. Apply Life-Cycle Costing

7. Focus on Quality

These principles were meant to inform decision making through each phase of the design and construction of projects They apply to the entire building life cycle from the initial planning phase to the design, construction and eventual disposal/ deconstruction of the built environment.Though simple, these principles apply to everything that is used to create and operate the built environment from the land, minerals, water, energy and ecosystems.

Benefits

Sustainable design and construction requires that all players from the building owner to the facility operator must be aware of these principles in order for the project to be successful. An often effective means of creating a successful project is to be sure that all key players in the building process are aware of the benefits of sustainable design and construction. The broad range of economic, environmental and social issues that sustainable design addresses enable just about everyone to find a benefit that they can agree with. Table 1 was developed by the Federal Energy Management Program (FEMP) to provide an overview of the potential benefits of Sustainable Design.

Table . Benefits of Sustainable Design (Source: Federal Energy Management Program, 2003)

Barriers

Listed below are some of the most significant barriers are often faced for accomplishing authentic ‘green’ design in State agencies. Following the description of each barrier is a list of suggested actions for overcoming the barrier.

ARCHITECTS AND ENGINEERS LACK KNOWLEDGE AND TRAINING IN GREEN DESIGN, AND THERE IS A STEEP LEARNING CURVE.

• Obtain training in green design through workshops and conferences offered by groups like the U.S Green Building Council.
• Participate in LEEDTM training workshops and encourage design staff to become LEEDTM Accredited Professionals
• Obtain knowledge about green design by reading various publications such as Environmental Building News and Environmental Design and Construction magazine and using green design tools such as the Green Building Advisor and GreenSpec6.
• Encourage and reward professionals who develop expertise in high performance building design.
• Prioritize green design and select design team members with appropriate experience and commitment

N-HOUSE DESIGN STAFF IS ALREADY OVERWORKED AND THERE IS NO TIME TO LEARN ABOUT OR IMPLEMENT GREEN DESIGN.

• Obtain a top-level commitment to green design which requires “finding the time” to make green design a priority.
• Move in-house staff in the direction of green design, incrementally, as workload permits
• Hire consultants to provide green design services which in-house staff does not have time for.
• Find ways to ease workload to allow for organizational growth and change.
• Add staff hired to work specifically on introducing green design into projects and implementing a culture change within the department.

FAST TRACK PROJECTS MAKE IT IMPOSSIBLE TO FIND THE TIME TO IMPLEMENT GREEN DESIGN.

• Find ways of slowing the pace of projects so that an integrated design process may occur – otherwise, designs will be less than optimal and potential life cycle savings will be lost.
• Hire consultants to provide green design services which in-house staff does not have time for.

FUNDING IS INSUFFICIENT TO COVER THE INCREMENTAL COST OF GREEN DESIGN.

• Seek dedicated green design funding for expensive green design measures from organizations.
• Seek design synergisms to reduce or eliminate increases in project first cost.
• Incorporate green technologies and design elements into building retrofit projects and finance them as part of larger energy conservation performance contracts.
• Use creative financing like that used in performance contracting to pay for green design premium costs in new construction.

GREEN DESIGN OR SPECIFIC GREEN MEASURES ARE PERCEIVED AS TOO RISKY FROM A COST, OPERATION, OR MAINTENANCE PERSPECTIVE.

• Recognize that well-managed green building designs are often delivered at no or low additional first cost.
• Make sure expectations and performance targets are realistic and relate them to the level of sophistication of operating staff and other resources.
• Bring operators on board during design and train them during commissioning

CAPITAL AND OPERATING BUDGETS ARE DISCONNECTED, MAKING IT DIFFICULT OR MPOSSIBLE TO USE FUTURE OPERATING SAVINGS STREAMS TO OFFSET ADDITIONAL PREMIUM “FIRST COSTS” FOR GREEN DESIGN AND HIGHER EFFICIENCY.

• Ensure all projects are examined from a life-cycle costing perspective.
• Develop budgetary mechanisms to bring extra funds to cover the costs of energy efficient or green design measures that pay for themselves and will reduce the life cycle costs of the building.
• Consider revolving funds which use energy savings as a mechanism for funding premium costs of green design.

CAPITAL PROJECTS ARE CONCEIVED, MANAGED, AND BUDGETED IN ISOLATION FROM OTHER PROJECTS, MAKING IT DIFFICULT TO OBTAIN THE ECONOMIES AND SYNERGIES OF INTEGRATED DESIGN.

• Establish mechanisms to ensure comprehensive asset management which requires capital project planning on a “whole building” and “whole campus” basis.
• Review capital asset management reports prior to funding new projects to ensure integrated design opportunities are optimized.

The Design Process

The design processes and strategies presented in the guidebook are intended to serve as a valuable resource for assisting government personnel, consultants and the general public in implementing sustainable design concepts into city construction and renovation projects. It serves not to replace the existing works such as LEED Rating System developed by the of the US Green Building Council but rather to augment these management systems by providing a concise summary of key concepts and up to date information pertaining to materials and technologies that are locally applicable in the Southwest Desert Region

TeamDevelopment

High-performance, sustainable, building design is accomplished through an integrated collaborative approach amongst many design disciplines. Linking the experience and expertise of professionals in landscaping, hydrology, civil, electrical, mechanical, architectural, interior design and plumbing from the onset of the project to its completion is vital to its success. Implementing a team approach can result in creating effective design solutions that achieve multiple benefits that would have otherwise been over looked.

There are several computer building energy modeling software tools such as the Department of Energy’s DOE 2.1E, eQuest,TM   Energy Plus, and Virtual Environment        that can be used to accurately predict the benefits of various design scenarios and combinations. These models need to be used early in the design process to be most effective. By inputting detailed building design information, climate data and mechanical system information different outcomes can be assessed and optimized for the most cost-effective combination of strategies of each particular project.

Often the most important step of any high performance design is to form an enthusiastic team of all stakeholders of the final project.With a team in place and in full communication, agreed upon project goals and a means of achieving them can be established.

Technical Strategies

The following strategies listed in this section cover the entire building process from site selection, building design, selection of materials and building operation. The strategies are purposefully concise in order to provide a quick overview of a large body of knowledge. Many of the strategies were taken from different design guidelines and adapted for use by a more general audience The strategies have been grouped into four main categories;

SITESELECTIONANDDESIGN PASSIVE SOLAR DESIGN

MECHANICAL AND ELECTRICAL SYSTEMS WATER MANAGEMENT AND CONSERVATION

• BUILDING LIGHTING, EQUIPMENT, ENERGY, MANAGEMENT, AND UTILITIES MATERIAL AND PRODUCT SELECTION

How to Use This Section

This part of the Guidebook has been developed as an easy-to-use reference guide. Each section contains multiple numbered subsections that provide a bulleted checklist of the more significant components of appropriate building design relating to desert climate and energy use. Where available, links to Phoenix regional resources are also provided. These will generally include overviews and contacts of local or state government programs relating to the topic.

Site Selection and Design

Buildings and outdoor living spaces are greatly affected by the physical features of the site, as well as the local microclimate that surrounds it. By taking advantage of the inherent site features a building or outdoor area can greatly be enhanced for optimal human comfort without a significant dependence on mechanical or electrical systems. If planned according to the strategies presented here, heating and cooling loads can be minimized, resulting in significant decreases in energy consumption and operational costs. In most cases small changes in the project’s orientation, configuration made during the initial planning stages can make a huge difference later on.The following design strategies will aid project teams when they are developing different site designs for their project.

SELECTING APPROPRIATE SITES

. AVOID DEVELOPMENT OF INAPPROPRIATE SITES AND REDUCE THE ENVIRONMENTAL IMPACTS FROM THE LOCATION OF A BUILDING ON A SITE.

Select sites without sensitive natural features and restricted land uses. Avoid prime farmland, wetlands, parkland, land in a floodplain, endangered species habitats, etc.

• Consider reuse of existing building space whenever possible.

1. 2.     DIRECT DEVELOPMENT TO URBAN AREAS. USE URBAN AREAS WITH EXISTING INFRASTRUCTURE, PROTECT GREENFIELDS AND PRESERVE HABITAT AND NATURAL RESOURCES.

• Give preference to urban and urbanized sites during the site selection process.

Site the building near mass transit whenever possible, minimizing transportation impacts.

Centrally locate sites to encourage walking and/or the use of bikes.

Joint use of facilities.Program for building use by community or other appropriate organizations. Consider integrating building function with a variety of uses, to improve community integration, increase security, and achieve other benefits

1. 3.     CONSIDER BROWNFIELD REDEVELOPMENT. REHABILITATE PREVIOUSLY UTILIZED AND/OR DAMAGED SITES WITH SUSPECTED OR CONFIRMED ENVIRONMENTAL CONTAMINATION, THEREBY REDUCING PRESSURE ON DEVELOPED LAND.

Give preference to brownfields sites during the site selection process.

• Develop and implement a site remediation plan using strategies such as pump-and-treat, bioreactors, land farming and in-situ remediation

Additional Resources

City of Phoenix Brownfield Program (602) 256-5669

http://phoenix.gov/BROWNFLD/brownfld.html

Arizona Department of Environmental Quality Brownfield Program: (602) 771-4401

http://www.azdeq.gov/environ/waste/cleanup/brownfields.html

Chase Field in Phoenix is home of the Arizona Diamondbacks and exemplifies a highly successful Brownfield redevelopment project.

SUSTAINABLESITE ANALYSIS AND DEVELOPMENT

1. 4.     EVALUATE THE SITE TO DETERMINE HOW BEST TO CONSERVE AND RESTORE ECOLOGICAL HABITATS AND SUPPORT BUILDING ENERGY AND RESOURCE EFFICIENCY.

Inventory and analyze microclimate characteristics, surface and underground hydrology, flora and fauna biodiversity, existing air quality and ground level wind patterns and man-made landscapes.

Map habitat corridors and stimulate healthy microclimates. Explore opportunities to connect surrounding open space with proposed green space on the site.

Map sun and shade patterns associated with new construction. Design landscaping features to take advantage of sun/shade for plants.

Examine opportunities to minimize disruption to existing hydrological features such as creeks, streams ponds, lakes and/or wetlands.

Test soil and groundwater to determine pollution levels, depth to water table, soil-bearing capacity, and what types of fertilizers or soil amendments may be required for planting.

Examine opportunities to restore the surface cover of impacted areas where existing topsoil is fertile and contains nutrients that support plant life, filters contaminants, and neutralizes and binds many air and water pollutants

Map natural hazard zones with exposure to high winds and storms, floods, unstable soils, steep slopes, earthquake fault lines, former (buried) water features, etc.

• Design building, parking, and roadways to complement existing site contours by limiting cut and infill.

Building orientation with respect to the sun’s seasonal patterns is one of the most important aspects of energy efficient design.

SITE DESIGN

1. 5.     CREATE IMPORTANT BUILDING AND SITE SYNERGIES

Complement the building with site features that minimize negative environmental impacts and restore natural systems. Organize building mass, orientation and outdoor spaces to provide efficient access, service, and recreational areas with multiple functions in addition to visual value. For example, rooftops can be used as gardens and for water collection; outdoor water features can be used for ambient evaporative cooling and as recreational space where people can gather. Use earth forms, plantings, drainage, water detention systems, and soils to support the functions of the building and site (e.g., screening, windbreaks, etc.).

Coordinate landscape design with building envelope. Orient building, windows, and outdoor spaces to take advantage of light, airflows, and interesting views.

Use deciduous shade trees and exterior structures such as arbors and trellises, louvers, overhangs and light shelves to reduce cooling load of the building.

Strategically placed vegetation can significantly reduce energy demand during the summer and winter months.

1. 6.     REDUCE POLLUTION AND LAND DEVELOPMENT IMPACTS FROM AUTOMOBILE USE BY ENCOURAGING ALTERNATIVE TRANSPORTATION.

Survey future building occupants to identify transportation needs and facilitate car-pooling.

Provide bus stop seating areas that are covered and wind-sheltered, or provide waiting areas within enclosed building lobby where appropriate.

Locating building near and provided for access to mass transit systems such as city bus lines is an important strategy for reducing regional energy.

1. 7.     PROMOTE BICYCLING FOR LOCAL TRANSPORTATION TO REDUCE POLLUTION AND LAND DEVELOPMENT IMPACTS FROM AUTOMOBILE USE.

Encourage bicycle or pedestrian access with site design features such as attractive landscape elements, walking and cycling paths, public squares, and public seating.

Provide bicycle amenities for building occupants, such as centrally located, secure bicycle racks and shower/changing facilities.

Work with the larger community to make bicycling safe and convenient.

1. 8.     PROVIDE CREATIVE PARKING SOLUTIONS TO REDUCE POLLUTION AND LAND DEVELOPMENT IMPACTS FROM AUTOMOBILE USE, ESPECIALLY SINGLE OCCUPANCY VEHICLES.

Provide preferred site parking for hybrid and alternative fuel vehicle owners, and vehicles used for carpools or vanpools. Minimize parking lot/garage size. Consider sharing parking facilities with adjacent buildings. Excess parking spaces encourage increased automobile use, contribute to urban heat island effects, and can increase pollution from stormwater runoff

1. 9.     PROTECT OR RESTORE OPEN SPACE, HABITATS AND BIODIVERSITY TO REDUCE SITE DISTURBANCE.

Limit “greenfield” site disturbance (including earthwork/clearing of vegetation) to no more than:

–   40 feet beyond the building perimeter (where the building perimeter includes adjacent paved areas and parking)

–   5 feet beyond primary roadway curbs, walkways and main utility branch trenches

–   25 feet beyond constructed areas with permeable surfaces.

On previously developed sites restore a minimum of 50% of the site area (excluding the building footprint) by replacing impervious surfaces with native or adaptive vegetation.

A well planned building design can meet the functional requirements while minimizes the total building footprint.

1. 0.  MINIMIZE THE AREA OF THE DEVELOPMENT FOOTPRINT IN ORDER TO REDUCE SITE DISTURBANCE. CONSERVE EXISTING NATURAL AREAS TO PROVIDE HABITAT AND PROMOTE BIODIVERSITY.

Design the building with a minimal footprint to minimize site disruption. Strategies include stacking the building program, tuck-under parking and sharing facilities with neighbors.

Designate an open space area adjacent to the building, equal to or greater than the size of the building footprint (for areas with no local zoning requirements).

Avoid negative impacts on adjacent facilities or open area properties. Typical impacts include reflected glare,

waste heat, light spill, noise from cooling towers, air handling equipment, and generators, as well as the shading of adjacent green space or buildings, and gusty winds at grade from wind tunnels created by new structures.

Cluster underground utilities running in conduits, such as telephone, cable, electric, water, wastewater.

Locate underground utilities in fire lanes as appropriate, to minimize site disturbance. (Separate sewer/water and high temperature piping as required.)

1. 1.  REDUCE OR ELIMINATE STORMWATER RUNOFF TO LIMIT DISRUPTION AND POLLUTION OF NATURAL WATER FLOWS.

Permeable pavements can reduce stormwater runoff from parking lots.

Maintain natural stormwater flows by designing the project site to promote infiltration

Specify garden roofs and pervious paving to minimize impervious surfaces. Pervious paving includes such materials as pervious concrete, porous asphalt, GravelPaveTM, and open grid pavements. More information on these materials can be found in the following chapter.

Reuse stormwater for non-potable uses such as landscape irrigation, and exterior site washing. Establish with the appropriate regulatory body that no adverse health effects would be associated with this water reuse. Underground cistern storage is preferable.

Prevent non-point source pollution by planting watershed buffers, allowing infiltration via porous surfaces, and minimizing paved parking areas.

Design roads and parking lots without curbs, or with curb cuts and openings, that drain to stormwater treatment and infiltration features

Minimize paved areas for sidewalks, roadways, and parking lots to the extent practicable to minimize stormwater runoff and also meet the needs of the building program.

1. 2.  TREAT STORMWATER ON SITE. LIMIT CONTAMINATION OF NATURAL WATER FLOWS BY ELIMINATING CONTAMINANTS AND INCREASING ON-SITE INFILTRATION.

Provide on-site stormwater treatment systems to remove suspended solids and phosphorus, and other contaminants. Consider natural treatment systems such as constructed wetlands, vegetated filter strips and bioswales to promote infiltration and “bio-remediate” the site’s stormwater flows. Such natural features remove gasoline, oil, grease, herbicides, fertilizers, etc., and reduce the need for constructed drainage channels and stormwater piping.

Provide grading and drainage via vegetated buffers to reduce the need for artificially constructed drainage channels and stormwater piping.

1. 3.  LANDSCAPE AND PAVE TO REDUCE “HEAT ISLAND EFFECT”

Provide shade within five years on at least 30% of the site’s non-roof impervious surfaces.

Utilize light colored paving (high-albedo materials) or open grid pavement for the site’s impervious surfaces, including parking lots, walkways, plazas, etc.

• Overhead photovoltaic covering offers another method to reduce the urban heat island effect while generating a renewable energy source.

The Joint City of Phoenix – SRP Pecos Park-n-Ride facility utilizes photovoltaic panels to generate a renewable energy source while mitigating the Urban Heat Island through shading of high thermal storage pavements.

1. 4.  UTILIZE SUSTAINABLE LANDSCAPE PRACTICES TO PROMOTE THE CONSERVATION AND RESTORATION OF EXISTING BIOLOGICAL AND WATER RESOURCES, INCLUDING SPECIES DIVERSITY, SOIL FERTILITY, AND AERATION.

Emphasize plant diversity. Select plants native or adapted to the region and microclimate. Consider those that grow together naturally, and are self-sustaining (i.e., can reseed and spread without much maintenance).Avoid invasive plant species and those that threaten local native ecosystems.

• Reduce the use of plant species that require frequent maintenance.

Avoid plants that require chemical treatment, especially pesticides. Use plant combinations and maintenance methods that do not require chemicals.

Avoid allergy-causing plantings adjacent to building openings such as air intakes, entries or operable windows. Use plants that contribute nitrogen to the soil (clover, honey locusts, black locusts, and legumes) to reduce dependence on fertilizers.

Promote large common root systems. Cluster rather than scatter site plantings to provide adequate root space for plants, especially street trees, and to help protect other plants from wind, sun, and reflected heat, and prevent erosion. Wherever possible, locate trees so that rooting zones of more than one tree can be combined.

Create larger planting islands.

Salvage native plants to be replanted on the site (or elsewhere) to preserve biodiversity.

1. 5.   REDUCE WATER USE FOR PLANT IRRIGATION

Use plants that do not require irrigation or that have water requirements that can be provided by natural precipitation patterns.

Reduce irrigation inefficiency by developing “planting zones” based on water use requirements. Clearly identify such areas on site plan drawings.

Consider drip irrigation where irrigation is necessary, or other water efficient irrigation systems. Avoid misting sprinklers, which waste water.

1. 6.  IMPROVE SOIL QUALITY.

Analyze planting soil to identify contamination and determine if remediation is needed.

Implement soil remediation measures as needed for the site such as introducing earthworms if they are sparse, adding organic matter and microorganisms to break down pollutants, and removing toxic materials Use mulch to conserve soil moisture, restore soil fertility, and reduce need for fertilizers.

Provide space and bins for composting landscape materials.

Passive Solar Design

Passive solar design refers to design techniques that maximize the beneficial aspects of solar energy while minimizing the negative effects. Passive solar design affects the building’s shape, orientation, glazing, thermal mass and many other static features of the building. This does not include the generation of electrical energy but it can include the using solar energy to heat water and drive the movement of air through natural, non-mechanical means.

SITING AND MASSING CONSIDERATIONS

1. 7.  OPTIMIZE SITE PLACEMENT AND BUILDING FORM TO REDUCE ENERGY LOADS.

Earth sheltered homes are able to achieve a greater energy performance.

Utilize topography. On hilly sites, utilize or modify existing topography to obtain the insulating effect of earth through berming, and other manipulations of the section.

Utilize/control wind on site Whenever possible, orient buildings to protect entrances and minimize infiltration from prevailing winter winds. During other seasons, take advantage of non-winter air movement by utilizing prevailing winds for natural ventilation

• Trees. Review location of existing and proposed deciduous and evergreen trees on site. Where feasible, locate buildings so that deciduous trees block summer sun to the south and west, and evergreens block winter wind
• Building Form/Massing. Maximize solar opportunities by elongating the building structure on its east-west axis. This orientation will allow use of sun-controlled natural daylight and winter solar gain, while minimizing summer heat gains and resulting cooling loads on the east and west facades of the building.
• Avoid use of large glass atria or large glazed surfaces that cannot be justified from a programmatic perspective or by operating savings returns (e.g., from passive solar heating).

INTERIOR LAYOUT/SPATIAL DESIGN

The layout of program spaces within buildings is often overlooked when considering energy use reduction. Well planned layouts can take advantage of passive solar heating and cooling. This in turn can result in the reduction in size of mechanical systems.The following strategies address the most important consideration in optimal spatial design within buildings.

1. 8.  ORGANIZE PROGRAMMED SPACES FOR MAXIMUM ENERGY AND RESOURCE EFFICIENCY AS WELL AS COMFORT.

Program the facility for efficient use of built areas (multi-functional spaces and appropriate net-to-gross). Avoid adding non-productive square footage to the building.

Group similar program functions to concentrate heating/cooling and simplify HVAC zoning loads.

Utilize public areas and circulation zones as thermal collectors and buffers. Such spaces tolerate a wider range of temperatures and greater temperature swings than continuously occupied spaces

Design building layout to utilize natural systems. Arrange occupied spaces for daylighting and natural ventilation whenever possible. Locate open occupied spaces adjacent to exterior windows and use borrowed light for interior offices. Utilize low partitions adjacent to window walls to enhance daylight penetration to interior areas

• Provide well-lit, pleasant, secure stairwells/staircases to encourage the use of stairs instead of elevators.

Combine water-use zones for plumbing to decrease heating and pumping requirements and reduce construction costs.

Open atriums utilize natural light and are conducive to interaction between building occupants.

1. 9.  UTILIZE PASSIVE SOLAR HEATING TO REDUCE FOSSIL FUEL ENERGY USE.

Design for direct solar gain for appropriate space types. Direct solar gain should be considered for all south-facing spaces where critical visual activities are not typically conducted, including public spaces such as atria, food courts,

circulation areas, etc

Utilize sunspaces where programmatically appropriate.

Consider mass walls Consider the use of interior south-facing opaque mass walls exposed to direct sunlight in the interior of a passive solar space or as a trombe wall to provide thermal storage during the day and passive heating at night.

Consider different design solutions for storing heat in the building structure or materials.

• Perform computer energy modeling to determine if a passive solar configuration saves energy in a cost-effective manner. Issues to be explored in this analysis include:

–   determining whether energy gains from passive solar heating will exceed energy loss due to additional fenestrations.

–   investigating the effect of south-facing glass with low U-value but high solar heat coefficient.

–   assessing the effectiveness of thermal mass.

PassiveCoolingandNaturalVentilation

1. 20.  EVALUATE THE POTENTIAL OF THERMAL MASS FOR BOTH EXISTING AND NEW BUILDINGS.

Moderate interior temperatures where appropriate through the use of sufficient thermal mass. Consider different design solutions for storing cooling in the building structure or materials.

Balance solar heat gain properties of glass by selecting high performance glass. Consider different types according to orientation and consider specifying appropriate solar heat gain coefficients and visible transmittances to reduce unwanted solar gain cooling loads.

Balance solar heat gain properties of glass with the effectiveness of other solar controls such as shading devices.

Use shading devices. Consider shading to let in natural light but exclude heat and glare and control contrast ratios. Shading strategies include vertical fins on east and west fenestration, overhangs or lightshelves on south fenestration, as well as arcades, trees, “brise-soleils,” and deep window insets.

1. 21.  NATURALLY VENTILATE THE FACILITY TO THE EXTENT POSSIBLE IN APPROPRIATE BUILDING TYPES, BUILDING ZONES AND/OR LOCATIONS.

Natural ventilation, unlike mechanically forced ventilation, uses the natural forces of wind and buoyancy to deliver fresh air into buildings. Fresh air is required in buildings to alleviate odors, to provide oxygen for respiration, and to increase thermal comfort. At interior air velocities of 160 feet per minute (fpm), the perceived interior temperature can be reduced by as much as 5°F.

Natural ventilation design utilizes natural wind patterns, air temperature differences and buoyancy to create currents within buildings.This example of a cooling tower is from the visitors center in Zion National Park, Utah.

Consider natural ventilation strategies in design of HVAC and exterior window and wall openings to reduce reliance on mechanical ventilation at least during swing seasons.Take local air quality and prevailing winds into consideration.

Design for cross ventilation. Develop other ventilation strategies where appropriate for the interior building space and

its function.These include cross ventilation through narrow floor plates, solar chimneys or other types of stack ventilation.

• Consider providing operable windows with appropriate HVAC interlocks or occupant annunciation systems to avoid HVAC operation and energy loss when windows are open.

Carefully balance the deficits of operable windows, which may compromise the efficiency and maintenance of central systems, with the psychological benefits of operable windows.

Consider fan-powered night ventilation in lieu of operable windows. Employ computer modeling to decide on the period for nighttime ventilation. In many situations, one or two hours of fan operation would be sufficient; longer run times may be ineffective and can waste energy. Night ventilation must be enthalpy-controlled, to avoid introducing excessive humidity in the building.

Utilize stack effect for cooling through high vent reliefs on stairwells, and other high outlets where smoke evacuation will not be compromised.

Additional References

How Natural Ventilation Works by Steven J. Hoff and Jay D. Harmon. Ames, IA: Department of Agricultural and Biosystems Engineering, Iowa State University, November 1994.

Inside Out Design Procedures for Passive Environmental Technologies by G.Z. Brown, B. Haglund, J. Loveland, J. Reynolds, and M. Ubbelohde. New York, NY: John Wiley & Sons, Inc., 1992. ISBN: 0471898740.

Passive Building Design: A Handbook of Natural Climatic Control by Narenda Bansal, Narenda, Gerd Hauser, and Gernot Minke. The Netherlands: Elsevier Science BV, 1994. ISBN: 044481745X.

Sky lights help bring natural light down to living spaces.

DAYLIGHT/SUN CONTROL

Nearly 40% of a buildings electric energy demand is due to the use of artificial lighting. Controlled daylighting should be incorporated into the building as the preferred source of illumination as often as possible.The optimal times for daylighting also correspond to the hours of peak energy use for cooling. Reducing the electric lighting can help mitigate peak loads during the day.The following techniques can greatly enhance the daylighting potential in new and existing buildings.

1. 22.  OPTIMIZE USE OF DAYLIGHT IN NEW AND RENOVATED FACILITIES.

Configure the fenestration system to achieve a minimum daylight factor of 2 percent (excluding all direct sunlight penetration) for most occupied spaces that are contiguous to an exterior wall, day lit atrium wall or roof, as a starting point in the design. Windows located below 30” and above 7’6” do not qualify for this calculation

Consider glare-protection strategies that minimize the time when interior-shading devices must be drawn (e.g., light shelves per 2.2.g.), and if vertical shading devices on the exterior are unacceptable for east and west orientations (e.g., due to first cost, views or aesthetics).

Achieve a line of sight to vision glazing for regularly occupied spaces, creating views and connecting indoors and outdoors. Exceptions would include copy rooms, storage areas, mechanical, laundry and other low occupancy support areas

Consider computer modeling of daylight spaces and design features to ensure that daylight spaces will be comfortable areas (with no glare) and that energy gains in terms of avoided electric lighting costs are greater than the energy costs from increased cooling loads.The heating load may decrease for south or even east-facing fenestration, or may be higher for other orientations. Enhance the favorable effect of glazed areas with glass selection, daylight harvesting systems

and coordination with HVAC controls. When evaluating additional energy loads caused by daylighting features, include the impact of additional square footage and increased surface area caused by spacious design elements like

atria. Seek design improvements to mitigate these loads so that daylighting and solar features reduce the energy load of the building, and do not add to it by creating additional space.

1. 23.  ORIENT BUILDING TO OPTIMIZE DAYLIGHT.

Create an elongated massing allowing for daylighting using north-facing and south-facing glass. An east-west elongated building with an appropriate overhang will permit effective daylighting while increasing winter solar gain through south glass, and reducing the direct penetration of summer sun.

Avoid exposed, eastern- and western-facing glass because of the large variation in light levels throughout the day and greater solar gains in the warmer months, resulting in increased cooling requirements. Eastern exposures are less problematic than the western ones in terms of heating and cooling costs.

Consider north facing glazing for occupants requiring more uniform levels of diffuse daylight.

1. 24.  SHAPE FORM TO GUIDE DAYLIGHT.

Incorporate courtyards or other daylight-enhancing techniques to bring light into interior spaces.

Evaluate such design elements to ensure that they do not add to building heating and cooling loads. Make design improvements as necessary to mitigate these loads.

Place and size glazing apertures appropriately. Maximize daylight through location and size of windows, roof monitors and skylights, and through use of glazing systems and shading devices appropriate to building orientation and space use.

Design to avoid glare by using top lighting such as monitors in the roof or ceiling plane that allow a greater quantity and more even distribution of daylight within spaces. Flat, bubble and low-slope skylights have a negative heat balance, but provide glare-free light with light-deflecting devices installed underneath them.

Consider high clerestory windows (often preferable to skylights) to provide deep daylight penetration especially for space types needing useable wall space.

Consider light pipe technology for top lighting in areas with relatively deep roof cavities to transmit natural light to deep interior spaces not reachable by other means.

Consider the use of interior and/or exterior light shelves, especially on south-facing windows, and on appropriate east or west facades for deeper daylight penetration. Light shelves avoid solar gain and glare of directbeam penetration and may eliminate need for use of mini-blinds on south facades. Some type of room darkening might be required in certain space types with audio-visual uses.

• Provide exterior shading devices (overhangs, vertical fins, projecting light shelves, etc.) where solar gain and direct light are undesirable

1. 25.  PROVIDE DAYLIGHTING CONTROLS

Design appropriate daylight harvesting controls. Review alternatives for reducing electric lighting use through daylight harvesting. Continuous daylight dimming has broad occupant acceptance, especially if, in individual spaces, it is coupled with a manual dimmer that allows for adjustment for maximum intensity of the artificial light from lamps. On/off or three-stage controls are appropriate for spaces with transitory occupancy (e.g., corridors) and where the glazed areas are large, so that the change from one light level to another rarely occurs. Manual dimming and switching lights on and off is typically done by occupants to enhance visual comfort rather than save energy

• Wire luminaries, where practicable, in parallel to the window walls, so they can be dimmed or turned off row by row

Additional Resources

AdvancedBuildingWeb Site

http://www.advancedbuildings.org/main_t_lighting_daylighting_controls.htm

Lighting Controls Association

http://www.aboutlightingcontrols.org/education/papers/daylighting.shtml

BUILDINGENVELOPE

A buildings exterior, commonly referred to as its envelope, separates the internal environment from the often harsh outdoor conditions. The envelope includes the walls, roof, foundations, doors, and windows of the building. Proper selection of these assemblies for these features will provide good thermal and moisture control while enhancing reductions in energy use. Natural energy can also be optimized by a well planned envelope the use of daylighting and passive solar techniques.

1. 26.  OPTIMIZE WINDOW FRAME PERFORMANCE.

Provide thermal break in metal window frames for best thermal performance and to minimize condensation.

• Consider security issues and water intrusion in glazing and design details
• Provide high performance, durable weather stripping to minimize infiltration.

Consider wood windows frames that provide a natural thermal break where appropriate in new construction (e.g. residential), and in window replacement on historic buildings.

Consider“pultruded”fiberglass window frames, which are insulated and are higher performance than wood or metal, for appropriate applications.

Energy efficient windows such as above depicted by Energy Star can provide substantial reductions on mechanical HVAC systems: Courtesy of Energy Star.gov

1. 27.  SELECT GLAZING FOR OPTIMAL PERFORMANCE

Select appropriate high performance energy characteristics. Consider U-value, solar heat gain coefficient, and visible light transmittance.

– Note: Each of these performance characteristics are testing and labeled on manufactured windows in accordance with standards of the National Fenestration Rating Council.

Optimize glazing by orientation using energy modeling. Glass on south, east and west facades should be highly protective against solar heat gain, except glazing that is protected by shading devices, or south-facing glazing being utilized for passive solar heating.

Consider specifying glazing with high visible light transmittance and high shading coefficients on north walls where glare is much less of a problem. Glass on north facades can be clear or lightly tinted.

Consider fritted, and spectrally selective glazing tuned to use and orientation on south, east or west elevations

Select appropriate color. Tinted glass for south, east, and west orientations should be in the blue/green family, which is ideal for daylit buildings since they have a high coolness index (visible light transmittance divided by solar

heat gain coefficient).

Additional Resources

American Council on Energy Efficient Economy

http://www.aceee.org/consumerguide/windows.htm

EfficientWindows Collaborative

http://www.efficientwindows.org/lowe.cfm

State of Arizona Energy Office

http://www.azcommerce.com/Energy/

1. 28.  PROVIDE EFFECTIVE INSULATION TO MINIMIZE HEATING, COOLING AND ENERGY USE LOADS.

Cellulose chips (left) and fiberglass (right) are two types of insulation commonly used.

Optimally insulate the building shell (walls, roof, basements/foundation). Utilize computer modeling to determine cost- effectiveness of adding insulation beyond code requirements.

Avoid thermal bridging in metal-framed assemblies through exterior wall, roof, and floor details and components

Avoid irregular exterior building shapes or soffits, which increase surface area, resulting in unwanted heat loss. Compensate for extra surface area with additional insulation

Additional Resources

NationalInsulationAssociation

http://www.eere.energy.gov/consumer/your_home/insulation_airsealing/index.cfm/mytopic=11510

1. 29.  CONTROL AIR AND MOISTURE IN THE BUILDING ENVELOPE.

Detail the building envelope to minimize infiltration and to prevent moisture build-up within the walls due to condensation. In humidified spaces that have masonry walls, do not place the insulation on the winter-cold surface of the concrete masonry wythe. If the insulation must be placed on the winter-cold surface of the masonry wythe, examine potential moisture condensation (dewpoint position).

• Ensure that all internal sources of humidity are properly ventilated.

1. 30.  REDUCE “HEAT-ISLANDS” FOR ALL BUILDINGS AND ROOF REPLACEMENTS.

Install new or replace existing roofs with high albedo roofs. Use highly reflective ENERGY STAR     compliant and

high emissivity roofing for the greatest amount of roof surface.                                        ^TM

• Consider installing new or replacing existing roofs with vegetated roofs. Review combinations of high albedo and vegetated.

Additional References

US EPA and DOE Energy Star Program:

http://www.energystar.gov/

Cool Roof Rating Council

http://www.coolroofs.org/

Mechanical and Electrical Systems

Mechanical and electrical systems are the life pulse of buildings. These systems provide the heating and cooling of water and air, the delivery and disposal of water and waste and provide access to power that drive appliances and artificial light. Providing these comforts of modern life demands considerable energy in the form of electrical and natural gas. With careful attention to design, these systems can work in concert with the building’s layout, orientation, envelope features, lighting strategies, electrical equipment, and site characteristics to reduce energy demand. Efficient design requires appropriate equipment sizing, efficient electrical device selection, and power distribution systems that incorporate renewable energy. There are several new strategies that can be utilized in existing and new design. These are generally categorized into two groups; those strategies that apply to the Mechanical Systems; energy sources, building processes, heating, ventilation and air conditioning (HVAC) systems, and those that focus on the Electrical Systems including power delivery systems, equipment loads and lighting.

ENERGY SOURCES

Best design practices must first address load reduction, then capitalize on solar heating, natural ventilation, daylight use, and other renewable strategies. Systems designers should explore renewable energy sources before resorting to conventional fossil fuel technologies.The benefits, in addition to the reduction of atmospheric pollution, include decreasing the State’s expenditures on imported fuel and power while augmenting investments in local jobs and materials related to renewable energy sources.

1. 31.  REDUCE USE OF CONVENTIONAL FUEL SOURCES.

Georgetown University Intercultural Center in Washington DC exemplifies a roof integrated PV system. Photo courtesy of Georgetown University

• Minimize heating, cooling, lighting and other energy loads.
• Minimize electric space or water heating.

Maximize use of passive solar heating and cooling in the design of new facilities and additions. Investigate passive solar technologies with the architect for heating portions of buildings such as lobbies, corridors, gymnasiums, cafeteria and other public areas. Consider the use of external shading of windows (particularly those on the south, west and east facades) to reduce summer solar gain.

Maximize day lighting in conjunction with reduction of electric lighting.

• Consider building-integrated photovoltaic systems.

Consider Ground Source Heat Pump (GSHP) systems where subsurface conditions allow and where cost effective and practical from a maintenance and operation perspective.

Consider ground cooling or cooling to a body of water as alternative to cooling towers, and ensure that this type of cooling will not have adverse environmental effects. In making the determination, consider

–   reduction in chemical treatment due to elimination of cooling tower

–   increase in cooling equipment efficiency  with associated reduction in emissions

–   increase in ground water or water body temperature, which is a problem if the increase is likely to be significant

–   whether the subsurface water or the surface water body is polluted.

Consider use of combined heat and power and distributed generation, e.g. micro turbines.

Encourage the use of purchased Green Power. Use grid-source, renewable energy technologies such as wind energy produced on grid-connected wind farms.

Investigate cleaner forms of hydrocarbon-based distributed generation systems, such as natural gas powered fuel cells and micro-turbines, particularly when waste heat is recovered.

HEATING, VENTILATING AND AIR CONDITIONING (HVAC) SYSTEMS

The following general approaches to use of Heating,Ventilating and Air Conditioning (HVAC) systems are recommended for new buildings, additions, and major rehabilitations of existing buildings to ensure an integrated approach to building and systems design for optimal energy efficiency and indoor air quality.

1. 32.  OPTIMIZE HVAC SYSTEMS THROUGH DESIGN INTEGRATION

Properly installed and maintained HVAC systems reduce operational costs and energy demand.

Design the architectural features (orientation, exposure, height, neighboring structures, present and future landscaping, performance of the building envelope, daylighting) in concert with selecting appropriate HVAC alternatives and sizing systems. Use acceptable computer modeling for all system choices.

Assess the interaction between the HVAC equipment and other related systems such as lighting, office equipment, fire protection, security, etc. in order to optimize design and energy efficiency.

Use separately zoned HVAC systems to serve areas with different users, loads, orientations, and hours of operation.

• Keep computer server rooms on separate cooling systems when rooms require continuous cooling.

Locate thermostats or other sensors to cover areas of similar load (similar occupancy and similar solar exposures).

Design for “diversity of use” assuming that not all spaces will be used at all times or with full occupancy or at full load.

Consider distributed air-handling mechanical rooms to reduce the size and complexity of ductwork systems. Special attention should be paid to noise control.

Evaluate the potential use of heat-wheels by performing a cost-effective analysis. Heat wheels area more energy efficient than glycol loops, but cost more and require additional space. Care should be taken to select systems appropriate for use in contaminated air streams such as laboratories

Evaluate heat recovery with glycol loops by performing a cost-effective analysis. Ideally, the glycol loops should have a summer bypass, so, during periods when the temperature differential is small (and sensible heat recovery is very inefficient), the heat recovery coil is bypassed; thus avoiding unnecessary increase in the fan energy.

Isolate building air intakes,placing them upwind and away from building exhaust air, loading dock, or parking lot vehicular exhaust air, as well as away from adjacent roadways, sewer vents, cooling tower spray, combustion gases, sanitary vents, trash storage areas and other sources of undesirable air contaminants.

Locate and design air intakes for the best air supply source for the HVAC system and in favorable direction for full airside economizer mode operation, as well as for minimizing snow intake in areas where this occurs.

Avoid use of ceiling plenums as return air ducts

Providelow-leak outside air dampers, which utilize separate dampers for minimum outside air and main outside air functions in order to accurately control minimum outside air intake quantities. Do not use main outside air damper to set minimum fresh air level

• Provide modulating dampers to ensure minimum outside air.
• Implement demand control ventilation.

Avoid rooftop units that preclude other roof top uses and add maintenance difficulty, which may result in inefficient operation. Always install air-handling units in accessible locations where they can be maintained.

COOLINGEQUIPMENTOPTIMIZATION

With building loads minimized, designers should select cooling systems and equipment based on meeting those loads at maximum efficiency.

1. 33.  MAXIMIZE COOLING EQUIPMENT EFFICIENCY

Select electric chillers that operate at high efficiency at full and anticipated part loads. Model overall chiller efficiency based on seasonal ton-hours at likely load profile (not just peak load). Consider variable speed drive chillers in this investigation.

Consider alternative cooling technologies, e.g. passive cooling and natural ventilation, natural gas-fired absorption or engine driven chillers with heat recovery or cogeneration, ground source heat pumps, etc.

Select high efficiency cooling towers, generally draw-through style. Provide variable speed drives on all cooling tower fans.

• Control the cooling tower operation with wetbulb reset instead of constant temperature.

Consider thermal energy storage (e.g. ice storage) as a means to avoid peak loads for cooling, especially if equipment sizes can be reduced. Example; district cooling using ice storage at Chase Field in Phoenix, Arizona. http://www.apses. com/content/northwind/press_releases/media20000516.asp

Consider water-cooled vs. air-cooled condensers on a systems efficiency basis. Also consider maintenance issues

(for cooling towers and cost of chemical treatment, water, and maintaining additional equipment). For water-cooled condensers, consider heat rejection to ground (open loop or standing column if water table is less that 50ft deep, or closed loop) or to adjacent water body.

Consider winter free-cooling from air economizers that can reduce district chilled water use and cost

Consider enthalpy heat recovery in conjunction with a reduction in the size of the chiller plant.

• Consider enthalpy-based economizers vs. sensible heat only.

Consider desiccant dehumidification. Address indoor air quality issues and operational lifecycle costs.

• Provide variable speed drives on chillers and chilled water pumps.

1. 34.  “RIGHT SIZE” COOLING EQUIPMENT

Avoid over sizing chillers or other cooling equipment more that recommended by ASHRAE.

Consider chillers of different sizes that could allow for more efficient part-load operation of the system, or chillers with variable speed drives.

Segregate spaces that need cooling from spaces that do not need it thus providing cooling only where required. Downsize cooling equipment accordingly.

• If an increase in cooling load is possible in the future, provide space in the central plant for another chiller, if and when it becomes necessary. Avoid purchasing and additional chiller now, since future chillers will be more energy efficient and more environmentally friendly. If you must purchase the additional capacity by significantly over sizing one of the chillers for the current facility, provide that chiller with variable speed drive.

DISTRIBUTION SYSTEM OPTIMIZATION

1. 35.  OPTIMIZE DISTRIBUTION SYSTEM

Use premium efficiency motors for fans and pumps to reduce operating costs and energy consumption.

Use variable air volume (VAV) systems to reduce operating energy cost of main air handling units unless analysis clearly indicates that an alternative system would be more cost-effective over the life cycle. Note that because of typical over sizing for AHU’s, a VAV system may even reduce that peak kW demand by the fan.

• Use variable speed drives to vary air and water volumes in order to reduce fan and pump energy requirements.
• Consider displacement-cooling methods to reduce cooling loads

Consider the use of under-floor air distribution systems in applications where this design produces efficiency, occupancy controllability, reliability, and renovation ease and cost benefits sufficient to justify added costs.

Design energy efficient ductwork, minimizing duct runs, duct velocity and duct resistance in order to reduce horsepower requirements and energy use.

• Locate ductwork to avoid exposure to building skin or outside temperatures.

Avoid three-way by-pass valves in order to reduce needless pumping.

Consider Direct Digital Controls to the VAV boxes, especially if the boxes have reheat coils. Minimize the reheat by increasing the air temperature when most boxes are in the reheat mode.

• Design for supply water temperature reset in heating and cooling loops.
• Find ways to insure high temperature deltas on chilled water loops.

Install flow or BTU meters to analyze distribution loads.

1. 36.  OPTIMIZE USE OF SENSORS

Consider providing a thermostat in every room (with digital readout and the ability for occupants to adjust temperature within a limited range consistent with temperature policy).

Locate sensors proximate to occupants for readings of temperature and carbon dioxide.

DOMESTICHOTWATER

1. 37.  OPTIMIZE HOT WATER SYSTEM

• Utilize low-flow water fixtures

Utilize energy efficient water heaters. Consider condensing water heaters to maximize efficiency. Consider retrofitting large, non-condensing DHW heaters with oxygen trim control.

• Do not oversize water heaters or hot water tanks

Utilize heat recovery methods when available, to provide service or domestic hot water.

Consider utilizing point-of-use water heaters for small loads and where hot water demand is spread out with a building.

• Consider solar water heating.

Consider alternatives to re-circulating hot water systems or employ and automatic control for re-circulating hot water systems to reduce temperature or cycle pumps off during hours of non-use.

Building Lighting, Equipment, Energy Management, and Utilities

Lighting design begins with daylighting. Why light interior spaces with electricity if better quality lighting can be provided by sunlight? Electric lighting should be designed to maximize savings from daylighting. Because lamp, ballast and light fixture efficiencies keep improving each year, it is possible to design high quality lighting systems with lower and lower wattage densities. More efficient plug load and hard-wired equipment is also now available, in part due to the Energy Star program. Building process utilities – like steam, compressed air, and purified water – can also be provided more efficiently. On-site co-generation of electricity can offer efficiency advantages. Electricity can also be provided from renewable sources with the purchase of grid- supplied “green power” or the on-site generation of electricity from building integrated photovoltaic solar electric panels.

ENERGY EFFICIENT LIGHTING

1. 38.  UTILIZE ENERGY EFFICIENT INTERIOR LIGHTING

Select the most energy efficient lamps, ballasts and fixtures to achieve low lighting densities (e.g. 1.0 watt per square foot or less in offices). Current lighting technology makes it possible to achieve footcandle thresholds with lighting wattage densities approaching 0.6 watts per square foot.

Use lamps with a high color-rendering index (CRI) for indoor use.The 841 series T-8 lamps are the current energy standard; these have a CRI of 82 and color temperature of 4100 K.

• Incandescent lights should not be used except when required in historic structures.

Use compact fluorescent lights in all “high hat” can-type fixture applications. High CRI, dimming, compact fluorescent lamps are available.

Compact fluorescent bulbs are part of a new generation of energy efficient lighting.

• Use T-5 lamps only where cost effective and where their higher lumen output can be utilized without creating glare. (T-5 fixtures may be appropriate for high bay lighting.)

Select fluorescent fixtures on the basis of efficiency. Consider reflectorizedfixtures (with fewer lamps) to maximize fixture efficiency. Consider high efficiency lenses to improve fixture efficiency. Avoid inefficient parabolic and paracube fixtures. Consider indirect or direct/indirect fixtures only if the watts per square foot efficiency is comparable to or lower than what would be achieved with direct fixtures

Utilize task lighting to permit reduced ambient lighting and lower lighting power density (watts per square foot).

• Select LED (light emitting diode) exit lights.
• Strictly minimize any decorative electric lighting.

1. 39.  USE LIGHTING CONTROLS TO REDUCE LIGHTING “BURN HOURS”/HOURS OF OPERATION.

• Provide multi-zone and multi-level switching for multiple use spaces.
• Incorporate time clock or energy management system controls, or infrared, ultrasonic or combination occupancy motion detectors in spaces where cost-effective.

Properly zone lighting circuits and switches to optimize energy efficient operation including perimeter zones using photocell control, dimming controls and daylight harvesting.

1. 40.  PROVIDE ENERGY EFFICIENT OUTDOOR LIGHTING

Use energy efficient high-pressure sodium fixtures to illuminate streets, parking lots, and walkways to achieve foot-candle thresholds

• Strictly minimize any outdoor decorative lighting.

Eliminate light trespass from building site by using energy efficient fixtures which direct light downward. Also consider cut- off luminaires, low-reflectance surfaces, etc., to prevent light trespass.

Meet IESNA standards Provide outdoor light levels and uniformity ratios that meet or are lower than those recommended by the Illuminating Engineering Society of North America (IESNA) Recommended Practice Manual: Lighting for Exterior Environments (RP-33-99).

ENERGY EFFICIENT EQUIPMENT

1. 41.  SELECT ENERGY EFFICIENT EQUIPMENT AND LOAD-CONSUMING DEVICES.

Specify only energy efficient plug load equipment for office, lab, kitchen, food service, vending, etc. Specify Energy Star label when available and /or equipment with built-in timers or power management features set as default to maximize likelihood of use

• Purchase liquid display (LCD) low wattage flat screens in lieu of conventional CRT monitors for computers.
• Use premium efficiency motors and controls.

Use variable speed drives to control all motors 5 hp. or greater that run for extended hours and where reduced, variable flow is possible.

Identify and use energy efficient alternatives for all other energy using equipment in building, e.g. elevators, compressors, and motors

1. 42.  UTILIZE EFFICIENT POWER DISTRIBUTION SYSTEMS.

• Distribute electricity at high voltage, consistent with safety and other applicable codes.

Consider utilizing direct current (DC) from photovoltaic systems, fuel cells, or other sources in lieu of conversion to alternative current (AC). DC may be appropriate for certain applications such as discrete lighting circuits or computer equipment.

Avoid electromagnetic pollution/exposure. Locate high voltage and high current electrical feeders, panel boards,

transformers or motors away from occupants/personnel. Provide electromagnetic interference (EMI) shielding if necessary.

ENERGYLOADMANAGEMENT

1. 43.  PROVIDE APPROPRIATE ENERGY MANAGEMENT

Digital energy meters and control systems.

• Use direct digital control energy management systems.

Provide building automation systems with the following characteristics:

–   Computerized monitoring and control of all major HVAC systems and equipment, capable of implementing full range of energy conservation and efficiency strategies.These should include setback strategies for when spaces are unoccupied.

–   Energy consumption monitoring and trend logging through hourly graphs to follow the effect of operational changes and monthly graphs to analyze historical data.

–   Load tracking and load anticipation capability to optimize system response to building pickup and power demand level.

–   Load shedding and demand control through scheduled equipment cycling.

–   Local controllers able to manage equipment operation independently and gather data for reporting.

–   Appropriate interconnection with central energy management systems if available.

Employ all appropriate peak-shaving strategies to reduce demand and flatten load profile when electricity is most costly. Consider shifting electric power consumption by utilizing thermal storage system in conjunction with a conventional chiller system.

Provide equipment controls for vending machine, water cooler and other refrigeration loads.

1. 44.  IMPROVE STRATEGIES FOR CONTROLLING HVAC AND VENTILATION

Operate based on need.Do not air condition all spaces. Do not air condition spaces when not in use.

• Eliminate or strictly minimize simultaneous heating and cooling. Design for zero reheating during the cooling season.

Turn off non-essential electric equipment during peak hours to limit electric demand.

Install CO2 sensors and implement demand control ventilation to allow for the reduction of outside ventilation air in large spaces with variable occupancy.Verify that recommendations are consistent with code requirements.

Provide supply air temperature reset controls for air distribution systems based on space occupancy. (Use appropriate control algorithms on VAV systems to avoid losing fan horsepower savings.)

1. 45.  PROVIDE FOR ONGOING ACCOUNTABILITY AND OPTIMIZATION OF BUILDING ENERGY AND WATER CONSUMPTION PERFORMANCE OVER TIME.

Develop a measurement and verification plan to enable continuous optimization of building energy performance by installing continuous metering equipment for appropriate end-uses specified.

ELECTRICALPOWERSYSTEMS

1. 46.  PROVIDE THE MOST EFFICIENT SOURCES OF POWER

• Avoid electric space and water heating.

Evaluate the cost-effectiveness in existing facilities of converting electric space and/or water heating to natural gas or some other energy source.

• Explore cogeneration and distributed power generation applications.
• Explore renewable energy sources and technologies.
• Explore the use of gas-fired micro-turbines or fuel cells.

Improve power factor by specifying appropriate equipment.

• Use high-efficiency and K-Rated transformers to serve non-linear equipment.

Avoidelectromagneticradiationexposure. Locate high voltage and high current electrical feeders, panel boards, transformers or motors away from campus occupants and school personnel. Provide electromagnetic interferences (EMI) shielding.

Install adequate metering to monitor electric loads

Water Management and Conservation

All new design should conserve water and protect water quality. There are many energy and environmental costs associated with wasting potable water. Sustainable design measures conserve water by increasing fixture efficiency and by avoiding technologies that waste water. With proper design, landscaping can be accomplished in a water efficient manner. Harvested storm water or recycled tap water (gray water) can provide irrigation when required.

WATER EFFICIENCY

1. 47.  CREATE WATER EFFICIENT LANDSCAPING. LIMIT OR ELIMINATE THE USE OF POTABLE WATER FOR LANDSCAPE IRRIGATION.

Perform a soil/climate analysis. Determine appropriate landscape types and design the landscape with indigenous plants to reduce or eliminate irrigation requirements.

Eliminate permanent irrigation systems through exclusive use of indigenous plant materials, allowing for temporary “quick couple” systems during the establishment period or extreme drought.

• Consider high-efficiency irrigation systems such as drip irrigation or soaker hoses.

Collect and use rainwater or gray water for landscape irrigation, urban gardening, and site washing purposes.

1. 48.  IMPLEMENT WATER USE REDUCTION STRATEGIES TO CONSERVE WATER. MAXIMIZE WATER EFFICIENCY WITHIN BUILDINGS TO REDUCE THE BURDEN ON MUNICIPAL WATER SUPPLY AND WASTEWATER SYSTEMS.

• Estimate the potable and non-potable water needs for the building.

Use high-efficiency fixtures or dry fixtures. Consider the use of low flow toilets and urinals (increasingly available), waterless urinals, and/or composting toilets.

Consider occupant sensors to reduce the potable water demand for lavatories.

Consider reusing stormwater and gray water for non-potable applications such as toilet and urinal flushing, mechanical systems, and custodial uses.

• Consider use of automatic, usually spring loaded shut-off controls on sinks to lower water usage.

Improve water efficiency of HVAC equipment. Do not utilize “one pass” cooling units that use potable water and discharge it to a drain.

Improve water efficiency of water-cooled cooling towers. Provide metering for both the makeup and the blowdown rate. Use a water analysis program to monitor water quality and to minimize blowdown rate.

Consider ozonation for laundering systems and cooling tower make-up water. Using ozone in lukewarm water reduces the need for detergents and bleaches in hot water and reduces energy use of laundering.

• Use only horizontal axis Energy Star compliant clothes washers.

Rainwater is collected from the roof and stored in drums to be used for watering plants outside a home in Guadalupe, Arizona.

1. 49.  USE INNOVATIVE WASTEWATER TECHNOLOGIES. REDUCE GENERATION OF WASTEWATER AND POTABLE WATER DEMAND, WHILE INCREASING LOCAL AQUIFER RECHARGE.

Consider reusing stormwater or gray water for sewage conveyance by installing a dual plumbing system for gray water use

For taller buildings, consider a black water system in lieu of gray water.The black water system will have a lower first cost, and its water saving features are more advanced.

Consider roof water harvesting Avoid lead, copper, or terne roofing, which can contaminate water sources. Recover groundwater Use excess groundwater from sump pumps to provide a source of recycled water. Consider a solar-aquatic installation or artificial wetlands to treat wastewater on site to tertiary standards.

Materials and Product Selection

There are many considerations required when selecting the appropriate materials and products used for high performance buildings. While traditional selection criteria such as cost, durability, performance and aesthetics remain very important in these buildings, sustainable design requires consideration of environmental and health issues related to their manufacture, installation and disposal. Methods for evaluating products for their environmental and health performance are often controversial and are still evolving. There are a growing number of regulated certification programs that provide evaluation and labeling for different sustainability criteria. As the evaluation methods have been improving the demand for materials and products has also rapidly grown. There are now a large number of building products with improved environmental characteristics and this is steadily increasing. It is important that design professionals have a working knowledge of the key environmental and health related criteria associated with different material types.

Environmentally preferable materials are those that are reused; recycled; low in embodied energy; renewable; sustainably harvested; non-toxic in production, use and disposal; and local (to reduce transportation impacts). Carefully selected materials can significantly reduce the environmental impact of new construction. In addition, planning recycling collection spaces and strategies for building occupants in the original design can reduce material waste over the life cycle of the building.

WASTE PREVENTION

1. 50.  CONSIDER RENOVATING EXISTING BUILDINGS INSTEAD OF NEW CONSTRUCTION TO EXTEND LIFE OF EXISTING BUILDING STOCK, CONSERVE CULTURAL RESOURCES, AND REDUCE NEW BUILDING ENVIRONMENTAL IMPACTS.

Consider reuse of existing buildings, including structure, shell and non-shell elements, and upgrading outdated components such as windows, mechanical, electrical and plumbing systems.

Remove elements that pose contamination risk to building occupants, and upgrade outdated components.

• Quantify the extent of anticipated building reuse.

1. 51.  USE MATERIALS EFFICIENTLY AND PREVENT WASTE.

Maximize resource conservation through efficient space design. Explore options for smaller buildings that still meet program through tight net-to-gross, compact form and use of multi-purpose spaces.

Consolidate program uses wherever possible, and co-locate communal spaces to reduce building area.

Design to accommodate future needs and anticipate future retrofit requirements.

• Reduce material used and waste generated through efficient design and detailing.

Design for disassembly and reuse of materials where possible, particularly for applications that are likely to change frequently.

• Eliminate unnecessary finishes in areas where not required.

Design using modular sizing of spaces and materials (as an organizing concept) to the extent practicable.

Select products for durability, educing replacement costs, occupant disruption and waste disposal.

Consider use of moveable partition systems and/or raised-floors systems to reduce churn costs and material waste.

1. 52.  REUSE MATERIALS. USE SALVAGED, REFURBISHED OR REUSED MATERIALS AS PART OF BUILDING MATERIALS PALETTE.

Establish a project goal for the incorporation of salvaged, refurbished or reused materials into the building design.

Identify materials and suppliers that can achieve the project goal.

Retain nonstructural elements such as roofing material, and portions of interior walls, doors, flooring, and ceiling systems, when doing major renovation of an existing building.

Consider salvaged materials such as beams and posts, floor coverings, paneling, doors and frames, cabinetry and furniture, brick and decorative items

Do not reuse materials and/or systems that contain toxins (e.g. lead, asbestos) and/or are not efficient (e.g. single-pane windows).

1. 53.  PROMOTE STORAGE AND COLLECTION OF RECYCLABLES.

Provide a dedicated recycling area, appropriately sized and easily accessible to serve the entire building for separation, collection and storage of materials including (at a minimum) paper, cardboard, glass, plastics, and metals. Provide appropriate access for collection vehicles.

Provide areas on each floor or in each major department for recycling collection stations consistent with facilities recycling program.

Consider employing cardboard balers, aluminum can crushers, recycling chutes and other waste management technologies to further enhance the recycling program.

• Provide easy to understand graphics and/or text for each material.

1. 54.  DIVERT CONSTRUCTION AND DEMOLITION DEBRIS FROM LANDFILLS BY RECOVERING USABLE RESOURCES.

Develop quantifiable waste management goals to redirect recoverable and recyclable materials back to secondary waste handlers

• Research local waste recycling market.

Develop appropriate specification language and details for the required Construction and Demolition Waste

    MATERIALSFORREDUCEDENVIRONMENTALIMPACTS

1. 55.  GIVE PREFERENCE TO MATERIALS WITH LIFE-CYCLE ANALYSES INDICATING AVOIDED OR REDUCED ENVIRONMENTAL DAMAGE.

• Avoid materials that may cause environmental damage in their manufacture, use or disposal.

Give preference to materials with low-embodied energy, where other performance criteria have been satisfied. Products with higher embodied energy involve more air emissions and pollution.

1. 56.  USE MATERIALS MANUFACTURED AND/OR HARVESTED REGIONALLY (WITHIN A RADIUS OF 500 MILES).

Establish a project goal for the incorporation of locally manufactured materials into the building design and identify local materials suppliers that can achieve this goal.

• Establish which of those materials are also locally harvested.

1. 57.  SELECT MATERIALS WITH RECYCLED CONTENT. CONSIDER BOTH POST-CONSUMER AND POST-INDUSTRIAL RECYCLED CONTENT.

• Note: Recycled content materials shall be defined in accordance with the Federal Trade Commission document, Guides for the Use of Environmental Marketing Claims, 16 CFR 260.7 (e).

Establish a project goal for the incorporation of recycled content materials into the building design and identify material suppliers that can achieve this goal.

• Conform to the most current consensus product standards for given product types and resource efficient materials. These standards have been developed by government agencies, environmental certification services, or trade organizations for environmentally preferable material selection.
• Consider alternative materials to plywood, such as composite boards, which use milling by-products, recycled paper, wood scraps, and/or agricultural waste.
• Consider composite products made from recycled materials, such as wood and plastic. It is important to use wood from sources that practice sustainable forest management.

Management Plan for the Contractor (General or Prime Contractor or Construction Manager) to implement.

1. 58.  USE CERTIFIED WOOD TO REDUCE NEGATIVE ENVIRONMENTAL IMPACTS ON FORESTS.

Specify Forest Stewardship Council (FSC) certified wood materials including but not limited to structural and general dimensional framing, mill-work, flooring, finishes, furnishings, and non-rented temporary construction applications such as bracing, concrete form work, and pedestrian barriers.

• Establish a project goal for the incorporation of FSC-certified wood products into the building design.

Identify material suppliers that can achieve this goal.

Reduce the use of large timbers by utilizing assemblies that require smaller pieces of wood, and by using glue-laminated beams and other types of prefabrication.

1. 59.  USE RAPIDLY RENEWABLE BUILDING MATERIALS (MADE FROM PLANTS THAT ARE TYPICALLY HARVESTED WITHIN A 10-YEAR OR SHORT CYCLE) FOR THE

MAXIMUM AMOUNT OF BUILDING MATERIALS AND PRODUCTS USE IN THE PROJECT.

Establish a project goal for the incorporation of rapidly renewable materials into the building design and identify material suppliers that can achieve the project goal.

Consider rapidly renewable materials such as linoleum, cork or bamboo flooring, poplar Oriented Straw Board (OSB), straw board or wheat grass for cabinetry materials, and others.

Consider the source of the material, with its effect on embodied energy, (e.g. bamboo from Asia, cork from Europe) and the toxicity of binders in the product (e.g. some bamboo flooring contains ureaformaldehyde binders).

ASSESSMENTOF MATERIALS

1. 60.  PROVIDE COORDINATED IMPLEMENTATION OF ENVIRONMENTALLY PREFERABLE MATERIALS DURING DESIGN AND CONSTRUCTION.

Develop specification criteria. Provide specification criteria for environmentally preferable materials selection and for their appropriate methods of installation. Criteria can be developed from product consensus standards and from additional materials guidelines.

Conform to the most current consensus product standards for low-emitting and resource efficient materials.These standards have been developed by government agencies, environmental certification services, or trade organizations for environmentally preferable material selection.

Identify material suppliers that can achieve these goals.

Research manufacturer or third-party certification Check for third party certification for manufacturer claims.

Quantify the total percentage of salvaged, recycled content, local and regional, rapidly renewable, sustainably harvested, low-embodied energy, and non-toxic low-emitting materials that are installed during construction.

• Provide documentation and manufacturers’ certifications

1. 61.  CONSIDER LIFE CYCLE COSTS IN PRODUCT AND ASSEMBLY SELECTION

Consider life cycle cost when selecting products. Durable, low maintenance products are often less expensive over time than other products that require frequent replacement. “Life Cycle Cost” typically the amortized annual cost of a product, including capital costs, installation costs, operating costs, maintenance costs, and disposal costs discounted over the lifetime of the product. Also consider environmental and health issues associated with product manufacture, use and disposal.

Additional Resources

US Green Building Council

http://www.usgbc.org/

Arizona Green Building Council

http://chapters.usgbc.org/Arizona/

Whole Building Design Guide

http://www.wbdg.org/

US Department of Energy: Office of Energy Efficiency and Renewable Energy

http://www.eere.energy.gov/buildings/highperformance/

References

Energy Information Administration (1991) Annual Energy Outlook. US Department of Energy. <http://www.eia.doe.gov/> Kibert, C. (2005). Sustainable Construction: Green Building Design and Delivery. New Jersey. John Wiley & Sons.

Krarti, M. (2000) Energy Audit of Building Systems: An Engineering Approach. CRC Press.

UB High Performance Building Guidelines (2004). University of Buffalo,The State University of New York.

USGBC (2006). LEED New Construction v2.2 Reference Guide. United States Green Building Council. Washington, DC. Van Der Ryn, Sim, and Stuart Cowan (1996). Ecological Design. Washington, DC. Island Press.

WBDG (2005) Whole Building Design Guide. National Institute of Building Sciences. <http://www.wbdg.org/index.php>

Chapter 4:

Systems, Materials and Technologies

Chapter 4 Table of Contents

Product Categories

ALTERNATIVE PAVEMENTS • 179

PASSIVE SOLAR DESIGN • 197

BUILDING ENVELOPE:THERMAL AND MOISTURE PROTECTION • 206

BUILDING ENVELOPE: OPENINGS • 233 ELECTRIC AND NATURAL LIGHTING • 252 HEATING AND COOLING SYSTEMS • 277 ONSITE ENERGY GENERATION • 304 WATER USE AND CONSERVATION • 32

VENTILATION AND INDOOR ENVIRONMENTAL QUALITY • 334

BUILDING AUTOMATION • 349

SERVICES • 358

Alternative Pavements • 179

Pervious Concrete • 180

Open-Jointed Concrete Pavers • 183 Open-Celled Pavers • 187

Ground Cover Support Structures • 191 Stabilized Graded Aggregate • 194

Passive Solar Design • 197 Passive Solar Energy • 198 Exterior Shading Devices • 201

Exterioir ShadingWithVegetation•203

Table of Contents Continued

Building Envelope: Thermal and Moisture Protection • 206

Airtight DrywallApproach • 207Dynamic Buffer Zones • 210 Raised Access Flooring • 213 Perlite Insulation • 217 Cellulose Insulation • 22

Cementitous Foam Insulation • 224 Ceramic Coatings   •   227 Mineral Wool Exterior • 230

Building Envelope: Openings • 223 Energy Efficient Windows • 244 Inert Gas Window Fills • 239 Operable Windows • 242 Spectrally Selective Glazing • 245 Warm Edge Windows • 249

Electric and Natural Lighting • 252

T5 Fluorescent Lamps • 253

Light Emitting Diodes (LED) • 255

High Efficient Flourescent Fixtures • 259 High Intensity Discharge (HID) Lamps • 262 Electronic Ballasts • 265

Fiber Optic Lighting • 265 Solar Tubes • 270 Switchable Glazing • 273

Table of Contents Continued

Heating and Cooling Systems • 277 Absorption Heaters And Chillers • 278 Alternative Refrigerants • 281

Water Source Heat Pumps • 285 Combo Space Water Heaters • 289

Desiccant Cooling Dehumidification • 292 Gas Fired Heaters And Chillers • 295 High Efficiency Rooftop Units • 296

Low NOx Burners • 298

RadiantHeatingAndCooling•301

Onsite Energy Generation • 304

Photovoltaic • 305

BuildingIntegrated Photovoltaic (BIPV) • 300 Cogeneration • 312

Wind Energy • 315 Fuel Cells • 318

Water Use and Conservation • 334 Rainwater Harvesting Systems • 322 Grey Water Recycling • 325

Ultra Low Flush Toilets • 328 WaterEfficientLandscapes • 331

Table of Contents Continued

Ventilation and Indoor Environmental Quality • 334 CO2   ControlledVentilation •  335DisplacementVentilation•339

Enthalpy Heat Exchangers • 342 Heat Recovery Ventilators • 345

Building Automation • 349

Day-Lighting Controls • 350 Occupancy Detection Sensors • 353 Building Automation Systems • 355

Services • 358

Energy Performance Contracts • 359

4

Product Categories

• ALTERNATIVE PAVEMENTS

• PASSIVE SOLAR DESIGN

• BUILDING ENVELOPE:THERMAL AND MOISTURE PROTECTION

• BUILDING ENVELOPE: OPENINGS

• ELECTRIC AND NATURAL LIGHTING

• HEATING AND COOLING SYSTEMS

• ONSITE ENERGY GENERATION

• WATER USE AND CONSERVATION

• VENTILATION AND INDOOR ENVIRONMENTAL QUALITY

• BUILDING AUTOMATION

• SERVICES

Climate, Energy & Urbanization

A Planners Guide to Sustainable Development in the Desert

178

ALTERNATIVE PAVEMENTS

• PERVIOUS CONCRETE
• OPEN-JOINTED CONCRETE PAVERS
• OPEN-CELLED PAVERS
• GROUND COVER SUPPORT STRUCTURES
• STABILIZED GRADED AGGREGATE

Pervious  Concrete

Applications

Parking Lots, Residential Streets, Sidewalks, Basketball and Tennis Courts

Definition

Pervious concrete is a special type of concrete that allows water and air to pass through it.

Description

Often referred to as ‘no-fines’ concrete, pervious concrete consists of;

• Portland Cement
• Coarse aggregate (stone)
• Water
• Admixtures

If mixed and formed according to specification, the resultant pavement will contain 15-25% void space with the concrete.The void spaces interconnect to form channels that allow water and air to pass through the pavement structure.

Benefits

• Prevents standing water from forming on pavement surface.
• Functions as a dry detention pond.
• Reduces capacity requirements for drainage facilities and discharge basins.
• Eliminates water pollution through natural biological processes.
• Recharges ground water aquifers.
• Improves the health of trees by improving the root system access to air and water.
• Absorbs and stores less heat than conventional pavements for UHI mitigation.

Limitations

• Durability under heavy traffic loads resulting in raveling.
• Maintenance issues associated with clogging.
• Limited experience among local contractors.
• Hazardous liquid spills difficult to clean up.

Typical Design Section

• 6” inches of pervious concrete
• 6” layer of clean aggregate provides structural support and temporary storage for water passing through the pavement.
• Non-woven filter fabric is placed below the aggregate to prevent migration of soil into the void spaces.
• A moisture barrier sheet is also desired at the junction between pervious and conventional pavement.

Maintenance

• Silts, clays, or heavy organic materials may clog pavement and reduce permeability. In most cases however, even at 99% clogging, permeation rates of 2-7inch/hour are observed.
  • Cleaning and inspecting every two years to ensure functionality as per specifications Cleaning methods include high pressure rinsing and vacuuming.

Additional Considerations

• Infiltration rates of native soil need to be at least 0.5 inch/hour
• Grade should have 0% slope.
  • An under drain below pervious pavement may be necessary for less permeable soils. Overflow structure and connection to storm sewer is required to handle instances of abnormally heavy rains.

LEED Credits

Pervious concrete is recognized by the LEED program. Pervious concrete may contribute LEED points in the following areas;

• Stormwater Management. By allowing water to soak through and infiltrate, pervious paving reduces stormwater flow and pollutant loads. Contributes to LEED Credit SS 6.
• Minimize Site Disturbance. By integrating paving and drainage, less site area may need to be used to manage stormwater, allowing a more compact site development footprint. May contribute to LEED Credit SS 5.

First Costs

• In the Phoenix Metropolitan area as of 2006, pricing is at approximately $5/ft2 for a 6” pervious concrete parking lot. This price includes the 4” aggregate base layer.
  • Integrating a stormwater pond and a parking lot into one unit can result in a large cost savings as compared to the conventional designs that include storm water drains and storm water sewer piping etc.

Life-Cycle Cost Considerations

There are additional costs associated with washing and inspecting the pavement throughout its lifetime. Many pervious concrete pavements have been in use for over twenty years before requiring replacement. The life of the pavement greatly depends on the quality of its initial construction as well as regular maintenance procedures.

Codes and Specifications that Apply

Pervious concrete, when used as part of a water management strategy may help to meet requirements for several City of Phoenix codes including;

• Chapter 32A GRADING AND DRAINAGE
• Chapter 32C STORMWATER QUALITY PROTECTION

A specification for pervious concrete is currently under development for the Southwestern United States. Several regions have already developed specifications for several states in the southeastern and northwestern regions.

Example Regional Contractors

CEMEX Inc

Website: www.cemexusa.com Phoenix Area Phone (602) 416-2652

Rinker Materials

701 N. 44th St

Phoenix, AZ 85008 Website: www.rinker.com

Phoenix Area Phone: (602) 220-5000

Progressive Concrete Inc. 2136 W. Melinda Ln Phoenix, AZ 85027

Website: ProgressiveConcrete.com Phone: 623-582-2274

Additional Resources and Case Studies http://www.concretethinker.com

http://www.concreteparking.org/pervious/pervious%20success%20stories.htm

Open-Jointed  Concrete  Pavers

Definition

Interlocking Pavers with inherent voids between blocks.

Applications

Sidewalks, driveways, terraces, roads, and small parking lots.

Description

Describe the functionality of material or technology. List the major components and describe their role in the overall system.

Benefits

• Permeability and reflectivity can mitigate urban heat island effect.
• Allows water and air to transfer through surface for healthy tree growth.
• Applicable for slow to medium speed traffic.
• Comparable in strength to Portland cement concrete and asphalts pavements.
• Aesthetics. Available in varying colors, shapes and sizes.
• No cure time. Immediately drivable.
• Long operational lifespan.
• Reduced costs of utility cuts repair.
• Contributes to LEED® Certification

Limitations

• Higher initial costs than conventional asphalt paving.
• Not as permeable as other alternatives.

Typical Design Section

Open jointed concrete pavers differ from common interlocking pavers in that they have either a spacer strip on each of the adjoining sides to prevent face to face contact between the surrounding pavers or they have indentations on the sides and corner that create void spaces even when the blocks are tightly jointed. The gap created by these techniques can create spaces that make up nearly 10% of the entire paved area.These voids allow for water and air to percolate into the base materials below the pavement. The joint is filled with sand during construction but remains permeable.

The general design and construction of open jointed concrete pavers remains very similar to that of standard interlocking pavers except that the base structure needs to be pervious as well.This can be accomplished through the use of washed large stone aggregate over a geo membrane to prevent the subgrade soil from rising up and filling the voids.

Installation and Maintenance

• Preparation – Once the a suitable subgrade is established for the project (infiltration rate of 0.5inch/hour) a geo membrane fabric is laid down before the stone reservoir of 3⁄4” washed aggregate stone is added.This followed by a based layer, or bedding layer, consisting of 1-2” of AASHTO No. 8 (3.8”) crushed stone.
• Placement – The units are placed manually or mechanically on the bedding layer and constrained by the edge restraints.The pavers are then vibrated using a high frequency plate vibrator which forces crushed aggregate into the bottom of the pavers and also begins compaction of the base layer. Sand is then spread into the joints until they are filled. Complete compaction turns the loose pavers into a tight, interlocking system that distributed vertical loads horizontally through shear force.
• Inspection – Determine if the open celled paver is free of sediment and debris such as mulch, leaves and other organic mater. Determine if standing water exists for long periods of time after a storm event. Make sure that the stormwater does not remain in the paver system for greater than 48 hours after an average storm. Check the paver system surface for structural deterioration, compaction or spalling once ever year.
• Maintenance and Repair – It is recommended that the paver joints be vacuumed as needed to remove organic debris that may cause reduced permeability. If undesired weeds or grasses begin to grow in joints it is recommended to you a nontoxic vegetation killing agent. In areas of the pavement where the pavement has completely failed it is recommended that full depth removal reconstruction of that particular section be completed.This does not compromise the surrounding paver system.

LEED Credits

Pervious interlocking concrete pavers may contribute to LEED points in the following areas;

• SS Credit 4.4. Minimize Site Disturbance. By integrating paving and drainage, less site area may need to be used to manage stormwater, allowing a more compact site development footprint. May contribute to one point.
• SS Credit 7.1. Urban Heat Island Effect. By using pavers that have a resulting reflectance of 30% or greater for more than 30% of all paved surfaces the project can gain at least one point towards LEED® certification.
• SS Credit 6. Stormwater Management. By allowing water to soak through and infiltrate, pervious pavers reduces stormwater flow and pollutant loads. May contribute to two points.
• MR Credit 5. Regional Materials. Because both the aggregate and binders is extracted and distributed in Arizona this material could contribute to at least 2 points in this LEED® category.

CSI Number, City Codes and Specifications that Apply CSI Code 02780 Unit Paver

Stabilized Aggregate, when used as part of a water management strategy may help to meet requirements for several City of Phoenix codes including;

• Chapter 32A GRADING AND DRAINAGE
• Chapter 32C STORMWATER QUALITY PROTECTION

Specifications – A wide array of specifications concerning interlocking pavers for all types of applications, soil conditions, and traffic loads is provided on the Interlocking Paver Institutes webpage, www.icpi.org.

Example Contractors

Advanced Pavement Technology (Illinois) Website: www.advancedpavement.com Phone: 877-551-4200

Air Void Block, Inc. (California) Website: www.airvolblock.com Phone: 805-543-1314

Capitol Ornamental Concrete Specialties, Inc. (New Jersey)

Website: www.capitolconcrete.com Phone: 737-727-5460

EP Henry Corporation (New Jersey)

Website: www.ephernry.com Phone: 800-444-3679

Pave Tech, Inc. (Minnesota) Website: www.pavetech.com Phone: 800-728-3832

SF Concrete Technology, Inc. (Ontario, Canada)

Website: www.sfconcrete.com Phone: 905-828-2868

UNI-Group U.S.A. (Florida) Website: www.uni-groupusa.com Phone: 800-872-1864

Unilock, Ltd. (Illinois) Website: www.unilock.com Phone: 800-864-5625

Additional Resources and Case Studies Interlocking Concrete Paver Institute Website: www.icpi.org

Phone: 202-712-936

Open-Celled  Pavers

Definition

Concrete pavers that integral void for grass or drainage material.

Applications

Driveways, firelanes and parking lots.

Description

Open celled pavers come in a variety of designs centered on the common functionality of providing permeability and vegetation growth while maintaining a significant amount of load bearing capacity. The pavers can range from single blocks of less than a square foot to slabs reaching areas of a square yard. The large voids that form the permeable portion of the pavement system can result in a 39% permeable surface area when summed over the entire movement. The voids are back filled with a grass turf or with a permeable crushed stone aggregate. Open celled pavers are typically installed over a gravel base course that acts as storage for stormwater as it infiltrates through the porous paver system into underlying permeable soils.

Benefits

• Vegetation, permeability and reflectivity can mitigate urban heat island effect.
• Allows water and air to transfer through surface for healthy tree growth.
• Applicable for heavy loads and high traffic volumes. .
• No cure time. Immediately drivable.
• Long operational lifespan.
• Reduced costs of utility cuts repair.
• Contributes to LEED® Certification

Limitations

• Higher initial costs than conventional asphalt paving.
• Reflectance depends on the concrete mix and aggregate properties.
• Grass turf will require watering in dry climates in addition to regular mowing.

Typical Design Section

Installation and Maintenance

• Preparation – Once the a suitable subgrade is established for the project (infiltration rate of 0.5inch/hour) a geo membrane fabric is laid down before the stone reservoir of 3⁄4” washed aggregate stone is added.This followed by a based layer, or bedding layer, consisting of 1-2” of AASHTO No. 8 (3.8”) crushed stone.
• Placement – The units are placed manually or mechanically on the bedding layer and constrained by the edge restraints.The pavers are then vibrated using a high frequency plate vibrator which forces crushed aggregate into the bottom of the pavers and also begins compaction of the base layer. Sand is then spread into the joints until they are filled. Complete compaction turns the loose pavers into a tight, interlocking system that distributed vertical loads horizontally through shear force.
• Inspection – Determine if the open celled paver is free of sediment and debris such as mulch, leaves and other organic mater. Determine if standing water exists for long periods of time after a storm event. Make sure that the stormwater does not remain in the paver system for greater than 48 hours after an average storm. Check the paver system surface for structural deterioration, compaction or spalling once ever year.
• Maintenance Activities – Inspect pavers surfaces for trash and organic matter such as mulch or leaves. Make sure all vegetated areas around the pavement system are stabilized and not draining into the pavement. Mow and remove clippings as required.

Vacuum sweep paver system to keep free of sediment four times a year. Repair failed areas by replacing the top and base layers of the damaged area. In repairing a section, undamaged pavers on that section can be reinstalled after new base sections have been placed.

LEED Credits

Pervious open celled pavers may contribute to LEED points in the following areas;

• SS Credit 4.4. Minimize Site Disturbance. By integrating paving and drainage, less site area may need to be used to manage stormwater, allowing a more compact site development footprint. May contribute to one point.
• SS Credit 7.1. Urban Heat Island Effect. By using pavers that have a resulting reflectance of 30% or greater for more than 30% of all paved surfaces the project can gain at least one point towards LEED® certification.
• SS Credit 6. Stormwater Management. By allowing water to soak through and infiltrate, pervious pavers reduces stormwater flow and pollutant loads. May contribute to two points.

CSI Number, City Codes and Specifications that Apply CSI Code 02780 Unit Paver

Stabilized Aggregate, when used as part of a water management strategy may help to meet requirements for several City of Phoenix codes including;

• Chapter 32A GRADING AND DRAINAGE
• Chapter 32C STORMWATER QUALITY PROTECTION

Example Regional Contractors Bomanite (California) Website: www.bomanite.com Phone: 559-673-241

D’Hanis (Texas)

Website: www.dhanisbricktile.com Phone: 800-299-9399

EP Henry Corporation (New Jersey)

Website: www.ephenry.com Phone: 800-444-3679

Hanover Architectural Products (Pennsylvania)

Website: www.hanoverpavers.com Phone: 800-426-4242

Hastings Pavement Company, LLC (New York)

Website: www.hastingsarchitectural.com Phone: 800-669-9294

Nicolock (New York) Website: www.pavestone.com 800-580-7283

Additional Resources and Case Studies

It is best to contact the product supplier to learn more about specific techniques, design specifications and case studies concerning the different options among open celled block pavers

Ground  Cover Support  Structures

Definition

A product used to increase the structural support of loose ground cover materials while maintaining their natural function and behavior.

Applications

Parking lots, fire lanes and erosion control.

Description

Interlocking open grid for stabilizing ground materials such as decomposed granite, soil, and vegetation. Usually made of a of recycled resins these support structures are laid down on top of a prepared subgrade and then filled in with natural materials.The open grid design supports heavy trucks and prevents the soils from shifting while still allowing full permeability.

Benefits

• Can support most all traffic volumes and loads.
• Can blend into the native landscape while controlling dust.
• Vegetation, high reflectivity and porosity help to mitigate urban heat island effect.
• Permeability prevents puddling and helps recharge groundwater.
• Very low embedded energy as compared to asphalt and Portland cement concrete.
• Very long lifespan.
• Simple installation and maintenance requirements.
• Made of recycled resins.
• Contributes to several LEEDTM point categories.

Limitations

• Not recommended for fast traffic areas
  • Grass field applications require watering, fertilizing and mowing and are not meant for areas with high traffic volumes.

nstallation and Maintenance

The generalized construction process of a ground support structure is provided below;

• Preparation – Prepare sandy gravel base course to a depth determined by a soils engineer. Check drainage rate of existing base course before add mat.
  • Placement of Filter Fabric and Mats – Cover entire area with filter fabric making sure to overlap at the joints between sections. Roll our open grid mats so that the sheets so that they will lock together.Trim section around curbs using scissors or saw. Hammer anchors at designated intervals to hold the mats in place.
  • Filling in With Soil or Gravel– Fill the open grid structures with gravel using front-end loader for large jobs and wheel barrow and shovel for smaller jobs. Use rakes and broom to evenly distribute the gravel to level slightly about the support structure.

• Compaction – Use a large driving roller or vibrating plate compactor to compact the gravel into the grid. Wetting the material may help the gravel interlocking.
• Inspection – Immediate drive over the surface to trouble shoot for any areas where gravel may in excess or additional compaction is required.
• Maintenance – When gravel is used, regular maintenance my include refilling in areas where gravel layer has been thinned out. Gravel section will also require raking and vacuuming of leaves to prevent excess organic build up.This can be accomplished as part of regular landscape maintenance. Grass covered support structures require watering in dry climates and will need regular trimming using standard mowing procedures. Do not aerate as this will damage the support structure.

Additional Considerations

• Slope should be considered as these structures perform better when the slope is less than eight percent.
• Underlying soils should have a percolation rate of 0.64cm to 1.3cm of water per hour.
• Bedrock should not be closer than two feet (0.6m) below the base course.
• Gravel and grass structures are not meant for areas where high speed acceleration or braking and turning occur. Examples of these areas include parking lot entrances and exits that connect to higher speed roads.

LEED® Credits

Ground cover support structures may contribute to LEED points in the following areas;

• SS Credit 4.4. Minimize Site Disturbance. By integrating paving and drainage, less site area may need to be used to manage stormwater, allowing a more compact site development footprint. May contribute to one point.
• SS Credit 7.1. Urban Heat Island Effect.The increase in surface permeability and potential to use highly reflective granite both contribute to at least one point for this credit
• SS Credit 6. Stormwater Management. By allowing water to soak through and infiltrate, pervious paving reduces stormwater flow and pollutant loads. May contribute to two points.
• MR Credit 4. Recycled Content. Most products in this category are made of post industrial or post consumer recycled resins they can contribute to as much as 2 points towards certification
• MR Credit 5. Regional Materials. Because the aggregate and soil can be extracted in Arizona this material could contribute to at least 1 point in this LEED® category.

Life-Cycle Cost Considerations

Most ground support products will have a useful life of 25 years in most climates when properly designed and maintained.

CSI Number, City Codes and Specifications that Apply CSI 32 12 43 Flexible Porous Pavers

Stabilized Aggregate, when used as part of a water management strategy may help to meet requirements for several City of Phoenix codes including;

• Chapter 32A GRADING AND DRAINAGE (refer to attached documents)
• Chapter 32C STORMWATER QUALITY PROTECTION

Specifications –The specification developed by Invisible Structure, Inc. for their ground support structure, GravelPave® can found in Appendix X.

Example Regional Contractors

Invisible Structure, Inc. (Golden, Colorado) Website: www.invisiblestructures.com Phone: 800-233-1510

GeoSupply (Arizona) Website: www.geosupply.com Phone: 602-305-8094

NDS, Inc. (California) Website: www.ndspro.com Phone: 800-726-1994

PermaTurf Co., Inc. (New Hampshire) Website: www.permaturf.com

800-498-4116

Presto Products Company (Wisconsin) www.prestogeo.com

Phone: 800-548-3424

RK Manufacturing, Inc. (Massachusetts) Website: www.rkmfg.com

Phone: 800-957-5575

Grid Technologies, Inc. (Rhode Island) Website: www.gridtech.com

Phone: 800-959-7920

Additional Resources and Case Studies www.epa.gov

Stabilized  Graded  Aggregate

Definition

Compacted crushed stone and sand held together by a bonding agent.

Applications

Walking paths, bike paths, driveways, fire lanes and parking lots.

Description

Crushed aggregate and sand that has been adequately mixed with a bonding agent is laid over a prepared subgrade.The water is added to activate the boding compound and the surface is compacted using multiple paths from a multi-ton roller with no vibration.The resulting surface is semi-permeable. Rate of infiltration can vary with the aggregate gradation.The surfaces look natural as whey will take on the same color of the stone aggregate. Chemical stains can added to the mix if additional colors are desired

Benefits

• Appears natural and blends in with desert landscape.
• High reflectivity and porosity help to mitigate urban heat island effect.
• Permeability prevents puddling and helps recharge groundwater.
• Lower embedded energy than asphalt and Portland cement concrete.
• Produced locally in Phoenix using regional materials.
• May help a project obtain several LEEDTM points.

Limitations

• Not meant for roads and heavy trucks.
• May experience some loose rocks in the first year of operation.
• Maintenance requirements.

Installation and Maintenance

The construction process of a stabilized aggregate pavement generally consists of the following steps

• Preparation – Make sure base course is adequately prepared and pre-soaked.
• Blending – Thoroughly mix stabilizer with crush stone/sand mix per specifications.
  • Placement/Compaction – Place the aggregate on top of the base and smooth out to desired grade. Add required amount of water and wait a designated amount of time (6-48 hours) before compacting. Compact the surface using a 1 to 5 ton roller making sure that separation and/or plowing does not occur.The roller should make 4 to 8 paths in total for adequate compaction.
  • Watering – A light spray of water is applied to the surface after compaction.
  • Inspection – A completed surface should be checked for the uniform and solid throughout, no evidence of chipping or cracking and no loose material should be present on the surface.

• Maintenance – Use a mechanical blower or hand rack as needed to remove, debris such as paper, grass clippings, leaves or other organic material. When snow plowing is necessary a rubber baffle or wheels should be attached to the plow blade to prevent damage to the surface.
• Repairs – If cracking occurs sweep fines into voids apply water and compact using an 8” to 10” hand tamp plate. For major damage, excavate area to full

depth and replace with new aggregate and binder and compact using hand tamp or larger 1000lb roller.Traffic must remain off of repaired section for 12 to 48 hours.

LEED® Credits

Pervious stabilized aggregate surfaces may contribute to LEED points in the following areas;

• SS Credit 4.4. Minimize Site Disturbance. By integrating paving and drainage, less site area may need to be used to manage stormwater, allowing a more compact site development footprint. May contribute to one point.
  • SS Credit 7.1. Urban Heat Island Effect. By using aggregate that have a resulting reflectance of 30% or greater for more than 30% of all

paved surfaces the project can gain at least one point towards LEED® certification.

• SS Credit 6. Stormwater Management. By allowing water to soak through and infiltrate, pervious paving reduces stormwater flow and pollutant loads. May contribute to two points.
• MR Credit 5. Regional Materials. Because both the aggregate

and binders is extracted and manufactured in Arizona this material could contribute to at least 2 points in this LEED® category.

Life-Cycle Cost Considerations

Stabilized aggregate surfaces will need to be inspected for damage at least every two years. If surface permeability is important to the project additional maintenance and cleaning requirements may be required. The life of the pavement greatly depends on the quality of its initial construction as well as regular maintenance procedures.

CSI Number, City Codes and Specifications that Apply CSI 02795 Porous Paving

Stabilized Aggregate, when used as part of a water management strategy may help to meet requirements for several City of Phoenix codes including;

• Chapter 32A GRADING AND DRAINAGE (refer to attached documents)
• Chapter 32C STORMWATER QUALITY PROTECTION

Example Regional Contractors

Soil-Loc, Inc. (Scottsdale, Arizona) Website: www.soilloc.com Phone: 480- 948-8144

Matrix Industries (Phoenix, Arizona) 602-758-2815

Soilworks, LLC (Gilbert, Arizona) Website: www.soilworks.com Phone: 480-545-5454

Stabilizer Solutions, Inc. (Phoenix, Arizona) Website: www.stabilizersolutions.com Phone: 602-225-5900

EarthCare Consultants, LLC (Phoenix, Arizona) Website: www.earthcareconsultants.com Phone: 888-792-400

Reclamare Company (Washington) Website: www.reclamare.com Phone: 206-824-2385

Additional Resources

National Stone, Sand & Gravel Association Website: www.nssga.org

Phone: 703-525-8788

Passive  Solar  Design

• PASSIVE SOLAR ENERGY
• EXTERIOR SHADING DEVICES
• EXTERIOR SHADING WITH VEGETATION

Passive  Solar  Energy

Applications

Passive solar energy design principles can be applied to any type of buildings. In hot climates, the design mitigates the sun’s heat; in cold climates the design takes advantage of it.

Definition

Passive solar energy is a technology which makes use of the building’s windows and materials to collect, store, and distribute the sun’s heat in the winter and reject solar heat in the summer without the use of mechanical or electrical devices

Description

Buildings designed for passive solar energy incorporate large south-facing windows and materials that absorb the sun’s heat.The longest walls run from east to west. In most climates, passive solar designs also must block intense summer solar heat. They typically incorporate natural ventilation and roof overhangs to block the sun’s strongest rays during that season.

Window design and glazing choices in particular, are critical factors for determining the effectiveness of passive solar heating system. In heating climates, large south-facing windows are used, as these have the most exposure to the sun in all seasons. In cold climates, large south-facing windows allow significant solar energy and also provide day lighting; properly sized overhangs can prevent overheating in the summer. In hot climates, north-facing windows can provide day lighting without heating the house.

In the other hand, east- and west-facing windows generally cause excessive heat gains in the summer and heat losses in the winter, and are usually sized small.

Benefits

• Passive solar design is highly energy efficient. Can reduce heating bills by as much as 50%
• Energy from the sun is free.
  • No investments in mechanical and electrical devices such as pumps, fans and electrical controls
  • Helps conserve valuable fossil fuel resources.
    • A well-designed and built passive solar building does not have to sacrifice aesthetics either
    • Passive solar design also reduces greenhouse gases that contribute to global warming because it relies on solar energy, a renewable, nonpolluting resource.

Limitations

• In areas where experienced solar architects and builders are not available, construction costs can run higher than for conventional homes, and mistakes can be made in the choice of building materials, especially window glass. Passive solar homes are often built using glass that, unfortunately, rejects solar energy. Such a mistake can be costly.

• On the other hand, passive solar heating tends to work best and be most economical in climates with clear skies during the winter heating season and where conventional heating sources are relatively expensive.

Maintenance

Minimal cleaning maintenance.

Additional Considerations

Room and furniture layouts need to be planned carefully to avoid glare on equipment such as computers and televisions.

LEED Credits

May apply to the Energy and Atmosphere section.

First Costs

Passive solar design can be used in most parts of the world. If designed by an experienced passive solar architect, buildings using passive solar design principles don’t have to cost more up front than conventionally designed buildings. And when they do, the savings in energy bills quickly pay for themselves.

Life Cycle Cost Considerations

Whenever integrating a passive solar energy design, it is important to think in terms of life- cycle costs rather than first costs. Life-cycle cost analysis takes into account factors such as durability, energy cost savings over a building’s anticipated life, and the component’s impacts on maintenance, replacement, and disposal costs, among other considerations. An increase in design cost of 2% to 4% over that of conventional buildings is considered acceptable for most sustainable, low-energy building designs. These increases, and those associated with materials and system enhancements, are often recouped in the first few years of operation through energy savings alone.

Codes and Specifications that Apply

Arizona’s Solar Energy Credit provides an individual taxpayer with a credit for installing a solar or wind energy device at the taxpayer’s Arizona residence. Qualifying technologies include solar domestic water heating systems, solar swimming pool and spa heating systems, solar photovoltaic systems, solar photovoltaic phones and street lights, passive solar building systems (trombe walls, thermal mass, etc), solar day lighting systems (excluding conventional skylights), wind generators, and wind powered pumps.

Source: http://www.ncsl.org/programs/energy/ArizonaFS.htm

Example Regional Contractors

Arizona Solar Center

c/o Janus II – Environmental Architects 4309 E. Marion Way

Phoenix, AZ 85018 http://www.azsolarcenter.com

Pictures

Source: http://www.engext.ksu.edu/ees/renewables/solar.htm

Source: http://www.daviddarling.info/encyclopedia/P/AE_passive_solar_heating.htm Source: http://www.ivydene1.co.uk/vamp/stnicks/centre.htm

Exterior  Shading  Devices

Applications

Multi-family housing projects, offices, administration buildings and other structures employing day lighting.

Definition

External shading devices incorporated in the building facade to limit the internal heat gain resulting from solar radiation.

Description

The use of sun control and shading devices is an important aspect of many energy-efficient building design strategies. In particular, buildings that employ passive solar heating or day lighting often depend on well-designed sun control and shading devices.

During cooling seasons, external window shading is an excellent way to prevent unwanted solar heat gain from entering a conditioned space.

The design of effective shading devices will depend on the solar orientation of a particular building facade. For example, simple fixed overhangs are very effective at shading south-facing windows in the summer when sun angles are high. However, the same horizontal device is ineffective at blocking low afternoon sun from entering west-facing windows during peak heat gain periods in the summer.

Benefits

• Reduces glare
• Reduces cooling loads
• Improves design aesthetics

Limitations

• Cleaning is a maintenance concern
• Increases capital cost

Maintenance

Need to be cleaned which turns out to be a maintenance concern

Consideration should also be given to ensure that the window washing process is not adversely affected by the sunshades.

Additional Considerations

Care should be taken to integrate the design with the glazing and/or curtain wall design. Other design considerations should include seismic and snow loading.

When designing shading devices, carefully evaluate all operations and maintenance (O&M) and safety implications. In some locations, hazards such as nesting birds or earthquakes may reduce the viability of incorporating exterior shading devices in the design.

LEED Credits

May apply to Energy and Atmosphere section.

First Costs

It depends on the design. Nevertheless, the architectural value and occupant comfort are central issues but are difficult to quantify.

Life Cycle Cost Considerations

The need to maintain and clean shading devices, particularly operable ones, must be factored into any life-cycle cost analysis of their use.

Example Contractors

Industrial Louvers, Inc 511 S. 7th Street Delano, MN 55328

Tel 1-800-328-342

(local) 763-972-298

(fax) 763-972-291

e-mail: ilinfo@industriallouvers.com

Ametco Manufacturing Corporation 4326 Hamann Parkway, P.O. Box 1210

Willoughby, OH 44096

Tel 1-800-321-7042

Fax 440-951-2542

e-mail: ametco@ametco.com

Pictures

Source: www.industriallouvers.com Source: www.industriallouvers.com Source: www.industriallouvers.com Source: www.industriallouvers.com Source: www.ametco.com

Exterior  Shading  with  Vegetation

Applications

Any kind of building

Definition

Deciduous vegetation planted around buildings to block summer sun and to reduce cooling energy demand.

Description

Deciduous vegetation is often an attractive and inexpensive form of shading, because it follows the local seasons, not the solar calendar.

The effectiveness with which trees provide shade and save energy depends on their tree density, shape, and placement.The dimensions of the shaded building, the position of the sun in the sky, and whether a tree keeps its leaves year-round also determine overall energy savings.

Benefits

• Researchers in a joint study by the Department of Energy’s Lawrence Berkeley National Laboratory (LBNL) and the Sacramento Municipal Utility District (SMUD) placed varying numbers of trees in containers around homes to shade windows and walls. Cooling energy savings ranged between 7% and 40% and was greatest when trees were placed to the west and southwest of buildings.
• Another LBNL study modeled the effects of shading homes with vegetation in seven

U.S. cities. By providing 20% tree canopy – the equivalent of planting one tree to the west and another to the south of a home – buildings could achieve annual cooling savings of 8% to 18% and annual heating savings of 2% to 8%.

Limitations

• Need maintenance
• Needs space for planting

Maintenance

Watering and occasional pruning, fertilizing and mulching.

Additional Considerations

Vegetation used for shading should be properly located so as not to interfere with solar gain to buildings in winter. Also note that trees require maintenance, pruning, watering and feeding. As they grow they change their shading pattern, and they can be damaged or killed, leaving the building exposed.

Deciduous trees should be planted on the east, southeast, southwest and west sides of buildings. Highest priority should be given to planting shade trees due west of west-facing windows. Select trees that can be planted within 6 m of windows and grow to be at least 3 m taller than the window

On the south side of a building, it is best to plant deciduous trees with high, spreading crowns that are near the building to maximize shading in the summer when the sun angle is high.

LEED Credits

May apply for Energy and Atmosphere section.

First Costs

It varies depending on the type of tree.

Life Cycle Cost Considerations

There would be some annual maintenance costs and time for watering and occasional pruning, fertilizing and mulching.

Example Regional Contractors

Arid Zone Trees

9750 East Germann Road Mesa, Arizona

480-987-9094

Fax: 480-987-9092

www.aridzonetrees.com

Klean-Rite Landscaping 2121 S Mill Ave Tempe, AZ

(480) 517-1949

Pdi Landscape Development 2020 S Mcclintock Dr Tempe, AZ

(480) 985-7777

Dicks Landscaping 915 N Mary St Tempe, AZ

(480) 429-8808

Pictures

Source: www.aridzonetrees.com Source: www.aridzonetrees.com Source: www.aridzonetrees.com Source: www.aridzonetrees.com

Building  Envelope:

Thermal  and  Moisture  Protection

• AIRTIGHT DRYWALL APPROACH
• DYNAMIC BUFFER ZONES
• RAISED ACCESS FLOORING
• PERLITE INSULATION
• CELLULOSE INSULATION
• CEMENTITOUS FOAM INSULATION
• CERAMIC COATINGS
• MINERAL WOOL EXTERIOR

Airtight  Drywall  Approach  (ADA)

Applications

It may be applied to new construction or retrofit. All types of buildings could make use of this technology: residential, industrial or commercial.

Definition

A building construction technique used to create a continuous air retarder that uses the drywall, gaskets, and caulking. Gaskets are used rather than caulking to seal the drywall at the top and bottom. Although it is an effective energy-saving technique, ADA was designed to keep airborne moisture from damaging insulation and building materials within the wall cavity.

Description

Infiltration and exfiltration of air in buildings have serious consequences, because they are uncontrolled; the infiltrating air is untreated and can therefore entrain pollutants, allergens, and bacteria into buildings. Air infiltration and exfiltration are the cause of unnecessary energy consumption in buildings due to the added heating and cooling loads and the additional humidification or dehumidification needed

The U.S. Department of Energy reports that up to 40% of the energy used by buildings for heating and cooling is lost due to infiltration. Using CONTAMW/TRNSYS modeling shows that in newer buildings infiltration is responsible for about 25% of the heating load and 4% of the cooling load (Emmerich, and Persily, 1998). To control air infiltration and exfiltration in buildings, a conceptual approach to air tightening is needed; an alternative is the airtight drywall approach (ADA).

The typical procedure for ADA is to seal any seams and joints where the foundation, sill plate, floor joist header, and sub-floor meet.The spaces between floors, the sub-floor, rim joist, and plates are also sealed.The wall-framing plates are sealed to the lower sub-floor and the upper rim joist. Gaskets are often used at the top and bottom wall plates (between the drywall and framing) and between ceiling drywall and attic joists.

Airtight electrical boxes (or standard electrical boxes sealed with caulk) complete the air barrier. Holes where pipes and cables pass through also need to be sealed before the wall and ceiling finishes are applied. After all this has been done and the perimeter drywall seams have been finished, the room is effectively sealed from expensive and uncomfortable drafts.

Such airtight buildings often consume one-third less energy when compared to similar unsealed buildings. Also, test measurements of airborne contaminants in an ADA-detailed building (including those with mechanical ventilation) found that the reduction of air infiltration did not diminish the indoor air quality significantly. However, for health and safety, it is strongly recommended that a heat recovery ventilator (HRV) or enthalpy recovery ventilators (ERV) be installed in an airtight home for proper ventilation.

Benefits

• Builders can adapt ADA principles to suit any design and varying construction schedules
  • Airtight buildings often consume one-third less energy when compared to similar unsealed buildings
  • Provides airtightening at the finishing stage of construction

Limitations

• Gaskets and caulking can be damaged by subcontractors when installing the drywall or utilities
• It is not a vapor barrier. If required, a separate vapor barrier must be used with ADA. Faced insulation batts, polyethylene plastic or vapor barrier paint work well.
• Requires special electrical boxes for best results

Typical Design Section

Maintenance

The application can be expected to last the life of the building with adequate maintenance and when dismounted can be recycled into new material.

Additional Considerations

Little training is required to apply ADA successfully.

LEED Credits

It may be applicable to the energy and atmosphere section of LEED.

First Costs

Materials and labor for standard designs should only cost a few hundred dollars. Gasket cost is approximately 15-20¢/foot.

Life Cycle Cost Considerations

Sealing the home with an advanced sealing technique, such as ADA, can make a big difference in winter heating bills and overall comfort, as well as reduce the infiltration of dust and other outside pollutants, such as pollen.

Codes and Specifications that Apply

Check local codes and regulations, restrictions may apply in some states. Example Regional Contractors

Atko Building Materials, Inc. 22255 N. Scottsdale Rd Scottsdale, AZ 85255

Phone: 480-585-7100

Fax: 602-254-953

Henry Products, Inc. 1425 N. McQueen Rd. Gilbert, AZ 85234

Phone: 480-926-1444

Fax: 480-497-8120

Thunderbird Building Materials 2808 N. 27th Ave Phoenix, AZ 85009-1707

Phone: 602-272-1394

Fax: 602-269-7930

Pictures

Source: www.southface.org Source: www.southface.org

Dynamic  Buffer  Zones

Applications

It could be applied to different building types: residential, commercial and industrial.

Definition

The DBZ is a technique to reduce moisture accumulation in external walls and halt their deterioration

Description

New buildings and restored buildings are frequently upgraded to higher indoor humidity levels. Buildings that are humidified and pressurized often suffer from wall or roof cavity condensation due to imperfect air sealing, higher indoor humidity and an air pressure difference. Furthermore, condensation in exterior walls and roofs can lead to corrosion, wood rot, spalling of masonry and mortars, mold production.

The primary reason for implementation of this type of design solution (DBZ) is to ensure elimination of moisture accumulation from either interior or exterior sources within the enclosure assemblies. Generally, the DBZ works in the following manner: dry conditioned air is forced into and out of interstitial exterior wall cavities by means of dedicated mechanical systems in such a manner as to constantly ensure positive pressure within the cavities relative to interior environments

Enclosure cavities are maintained at such low absolute humidity that the cavity air maintains a dew point temperature below the outdoor temperature for most of the time during winter. Since these types of building enclosures rely on mechanical systems, performance verification and commissioning are key components to the success of the assembly to achieve its objectives

A DBZ system, which can control construction cavity condensation effectively is gaining market acceptance for many types of buildings. There are two types of dynamic buffer zone (DBZ) systems, the ventilated cavity DBZ system and the pressure controlled cavity DBZ system.

In the ventilated cavity system, the construction cavities are ventilated with dry outdoor air and pressure relieved or controlled through a return and exhaust system. In some cases, the cavity air is recirculated if the dewpoint temperature of the air is low and the cavity air requires supplementary heat.Ventilated cavity systems have had limited application in buildings due to the complexity of the system, the required controls and poor performance in some applications.

In the pressurized cavity DBZ, the construction cavities are pressurized slightly above the indoor pressure of the building with preheated outdoor air but without a pressure relief or return air system. These systems are less expensive to design and build and more efficient at controlling construction cavity moisture conditions; however, pressurized cavity designs cannot provide perimeter heat.

Benefits

• Prevents condensation in exterior walls
  • DBZ can make heritage buildings more comfortable places to work, eliminate the need for costly retrofit projects, and has the potential to reduce energy costs.

Limitations

• Indoor air quality problems if there are imperfect seals between the building and the wall cavity
• Ventilation design may result in decreased condensation control Preheating outdoor air may increase energy costs

Maintenance

A DBZ system may include supply and exhaust fans, temperature, RH and pressure sensors and controllers, sealed cladding components and a sealed interior plane of airtightness.These devices will need regular maintenance orders.

LEED Credits

May be applicable to the energy and atmosphere section.

First Costs

The cost of the application varies with the project building type and the area of application. However, from experience, the cost of modifying an exterior wall to perform as a DBZ system can vary between $220 and $350/m2.

Codes and Specifications that Apply

Building codes will vary, check local regulations. Example Contractors

Rick Quirouette, B. Arch Quirouette Building Specialists Ltd. 532 Montreal Road, Suite 107 Ottawa ON

Canada K1K 4R4 tel 1 613 260 2224

fax 1 613 260 2228

rick.quirouette@sympatico.ca

Pictures www.sustainablebuilding.com

Raised  Access  Flooring

Applications

The increasing demands for flexibility and information technology in the workplace have brought Access Flooring to be applied into offices, police stations, colleges, hospitals and many other environments. Access floors are designed into new buildings and can usually be accommodated into existing buildings, built before the demands of the modern workplace, as part of a refurbishment project.

Definition

Access floors are defined as a system of panels and supports that create a raised floor above the actual structural floor. By raising the floor up, a space is created in between the raised floor and the building structural floor where functional components like wiring for power, voice, and data can be routed and plumbing lines located. This space in between has also become increasingly valuable for heating, ventilation, and air conditioning (HVAC) distribution either as a plenum space or with defined ductwork.

Description

Access Flooring is used worldwide in offices, computer rooms, control rooms and now in some retail shops. It is sometimes referred to as , raised access flooring, safety flooring or industrial flooring. The raised floor provides numerous benefits in the provision of services during the building construction and its subsequent use as it is possible for the raised access floor panels to be lifted as required.

The cabling and cooling requirements of early mainframe computers led to the birth of Access Flooring – in simple terms panels (which are normally 600mm square) supported at the corners with pedestals down to the structural floor.This creates an accessible under floor void through which cables, ventilation and other services can be run.

Today’s office worker typically requires access to data cables as well as telephone and power outlets. All of these requirements and changes need increased flexibility and a strategy to reduce the rate of churn and the cost of continually reconfiguring offices. Raised access flooring provides the answer by creating a fully accessible floor void in the room through which cables and/or ventilation can be run.Telephone, data, and power outlets can be mounted directly in floor panels, and these panels can be relocated quickly and easily for rapid reconfiguration.

The finishes available for raised access floors include

• Vinyl, Linoleum, Caouchoc, Flex
• Velour, Needlefelt Carpets
• High Pressure Laminates, Wooden Parquet
• Loosely laid covering tiles

• Natural stone and ceramic

i.e. Wood core floor systems are ideal for projects where the architect / client do not have a specific requirement for sound insulation or fire protection.This type of raised access floor system is suitable for bonding anti-static vinyl, or for using loose laid carpet tile.

The system preferred over the traditional wood core panel is the Goldbach Norit Calcium Sulphate system.This raised floor system provides the client with a solid feel floor.This system has been manufactured from approximately 95 – 97% of recycled material.

Something important to know on access flooring is that holes are normally cut in panels for cable entry or ventilation. Cable entries are usually under machines and vents are more commonly in exposed positions. Panels with hole-cuts in them are inevitably of reduced strength. The amount by which the strength of a panel is reduced will depend on the shape and the position of the cut out and its dimensions.

Therefore, caution should be exercised in placing panels containing cut-outs in areas which are likely to be heavily trafficked by rolling loads.When equipment is being moved or maneuvered, spreader plates should be used.

Benefits

The savings, convenience, flexibility and more of access flooring systems makes having a raised floor a sustainable option, some of the benefits are as follows:

• Reduced wiring costs from traditional cable management practices, approximately 40% upon installation and reconfiguring costs can be eliminated up to 85%.
• It’s easy to move HVAC air handlers and power, voice and data connections.
• No ladders required.
  • Access flooring systems are noncombustible, solid, quiet, lightweight for handling ease, excellent grounding and electrical continuity, interchangeable with other panel strengths and have great rolling and ultimate load performances.

Limitations

• Higher initial costs
• Not recommended on exterior applications

Typical Design Section

Maintenance

The substructure should be checked whenever the opportunity presents itself. In order to prevent small problems becoming serious, adjustments and repairs should be made as quickly as possible. The remedy may be as fast and simple as changing standard panels in high traffic areas with others, which are in more remote positions.

LEED Credits

The United States Green Building Council (USGBC) has identified access flooring systems as a way to improve indoor air quality through their Leadership in Energy and Environmental Design (LEED) program.

First Costs

Typical raised access flooring systems can be installed for under $7 a square foot.

Life Cycle Cost Considerations

The life cycle costs will be derived from the amount of maintenance required.The repairs or services likely to be needed will depend upon function and the type and volume of traffic across the floor

Codes and Specifications that Apply

International and National building codes may be applicable for electrical, seismic and other safety issues. i.e. International Building Code (IBC) and the BOCA National Building Code (BNBC).

Example Regional Contractors

ABTECH, Inc

1567 E. Edinger Ave. Anaheim, CA 92705

Phone: 714-550-9961, 800-394-7699 (toll free)

Fax: 714-550-9807

http://www.abtech.net

McNichols Co

5525 W. Latham St., No. 7 Phoenix, AZ 85043-1601

Phone: 602-235-9733, 800-237-3820 (toll free)

Fax: 602-235-9734

http://www.mcnichols.com

Pictures

Source: www.resourcefloors..com Source: www.raisedfloor.co.uk Source: www.ledportinteriors.com

Perlite  Loose  Fill  Insulation

Applications

The physical properties of perlite include the product’s lightweight feature, absorption ability and insulation values.These features make perlite applicable in many areas.These applications can be broken down into three general categories: construction applications, horticultural applications, and industrial applications. In this case, the focus will be perlite as insulation in construction and industrial area. More specifically, an example will be described of perlite loose fill insulation; this product is used in construction and could be applied to any type of new or retrofit building.

Definition

On the first hand, and as a background, it is relevant to mention that Perlite is not a trade name, is a naturally occurring siliceous rock that expands 4 to 20 times its original size when rapidly heated to approximately 3,000 °F. In reality, expanded Perlite is a “popped rock” that is inert, lightweight, sterile, permanent, incombustible, asbestos-free, non-toxic, rot and vermin proof and has a neutral pH. OSHA classifies it as a nuisance dust.

On the other hand, more specifically, Perlite loose fill insulation is an inert volcanic glass expanded by a special heat process that can be treated with water repellent material when necessary. The resultant lightweight product is a white granular material, which handles and pours easily. It provides a quick, inexpensive and permanent method for efficiently insulating masonry walls.

Description

Perlite is used in construction, it is substituted for sand or heavier aggregates in concrete and plaster mixes to reduce weights and achieve better insulation and fire protection. Perlite is naturally incombustible, resistant to thermal transmission and lightweight. Using lighter Perlite materials means that, in turn, structural building elements can be smaller, lighter and less expensive.

Perlite is also ideal for insulating low temperature and cryogenic vessels. When perlite is used as an aggregate in concrete, a lightweight, fire resistant, insulating concrete is produced that is ideal for roof decks and other applications. Perlite can also be used as an aggregate in Portland cement and gypsum plasters for exterior applications and for the fire protection of beams and columns. Other construction applications include under-floor insulation, chimney linings, paint texturing, gypsum boards, ceiling tiles, and roof insulation boards.

In regards to perlite loose fill insulation, this technology has several features. One of them is thermal insulation, the efficiency and economy of perlite loose fill insulation has been proven many years in the insulation of storage tanks for liquid gases at temperatures as low as -400 degrees F (-240 degrees C).This characteristic is also exhibited in construction, depending on design conditions, reductions in heat transmission of 50 percent or more may be obtained when perlite loose fill is used in the hollow cores of concrete block or cavity type masonry walls

The next feature is permanency, Perlite is inorganic and therefore rot, vermin, and termite resistant and non-combustible with a fusion point of approximately 2300 degrees F (1260 degrees C). It is as permanent as the walls which contain it.

The next special characteristic is the fire rating, a UL design shows that a 2-hour rated 8, 10, or 12-inch concrete block wall is improved to 4 hours when cores are filled with perlite. One last feature is sound reduction; Perlite loose fill insulation has the ability to fill all voids, mortar lines, and ear holes thus enabling it to reduce airborne sound transmission through walls. Lightweight 8” masonry block filled with perlite achieves an STC of approximately 51 which exceeds HUD sound transmission standards

Benefits

Perlite loose fill insulation functions as a permanent, non-toxic, non-combustible, rot-proof insulation which minimizes winter heat loss and summer heat gain.These properties allow for greater comfort at lower long-term cost.

Thermal performance tests using ASTM C-236 Guarded Hot Box Method have shown conclusively that perlite masonry loose fill insulation is the superior concrete block insulation when compared to expanded polystyrene (EPS) inserts, expanded polystyrene (EPS) beads, and vermiculite

Limitations

Perlite loose fill insulation should be installed in well sealed cavities and masonry. All holes and openings in the wall through which insulation can escape must be permanently sealed or caulked prior to installation of the insulation. Copper, galvanized steel or fiberglass screening must be used in all weep holes.

LEED Credits

It may be applicable to the energy and atmosphere section of LEED. First Costs

Insulation is essential in all construction for energy conservation.The original cost of installing perlite loose fill insulation can be recovered quickly due to substantial reductions in heating and air condition energy consumption. In addition, perlite loose fill insulation cuts installation costs since it is lightweight and pours easily and quickly in place without need for special installation equipment or skills.

Life Cycle Cost Considerations

A well insulated building should provide lower operational costs, greater conformity to environmental concerns, greater thermal comfort and often also greater soundproofing. Basically there are no operational costs due to maintenance, unless the insulation was applied without correctly sealing cavities before its application.

Codes and Specifications that Apply

• ASTM Specification C549 for Perlite Loose Fill Insulation
• ASTM Specification C520 Density of Granular Loose Fill Insulation
• ASTM Specification C236 Test Method for Steady-State Thermal
• Performance of Building Assemblies by Means of a Guarded Hot Box
• ASTM Specification E84 Test for Surface Burning Characteristics of Building Materials
• FHA Use of Materials Bulletin UM-37
• GSA Commercial Item Description A-A-903 Insulation,Thermal (Expanded Perlite)
• Brick Institute of America Technical Notes No 21A
  • Federal Specification HH-I-515D Example Regional Contractors

Harborlite Corp.

P.O.  Box  960 Superior, AZ 85273-0960 Phone: 520-689-5723 Fax: 520-689-2362

Therm-O-Rock Inc 6732 W. Willis Rd Chandler, AZ 85226

Phone: 520-796-1000

Fax: 520-796-0223

Horizon Energy Systems 610 E. Bell Rd., #350

Phoenix, AZ 85022-2393

Phone: 602-867-3176

Fax: 602-863-9915

Atlas Energy Products 222 S. Date

Mesa, AZ 85210

Phone: 480-969-5966

http://www.atlasroofing.com

Pictures

Source: www.perlite.net Source: www.rolledalloys Source: www.coldcrossing.com

CELLULOSE INSULATION

Applications

New constructions or retrofit buildings of any type: residential, industrial or commercial.

Definition

Cellulose building thermal insulation is a recycled material made from recovered newsprint and other paper (wood fiber) feedstock; it also has low embodied energy and typically delivers superior installed insulation performance.

Description

Cellulose insulation is made from recycled paper that is applied as either loose fill into attics and closed wall cavities or damp-sprayed into open wall cavities. Due to this recycled content and potentially higher energy and acoustic performance, cellulose is an environmentally- preferable product.

In the installation process, loose fibers are blown into building cavities or attics using pneumatic equipment. Some installers attach netting to the face of open wall and ceiling cavities and blow in loose cellulose. Cellulose can also be damp-sprayed into open wall cavities before the drywall is applied. In this case, the damp sprayed cellulose should have less than 25% water content before closing the cavities with drywall; if the moisture level is not tested it could lead to moisture and mold problems.

In both cases, and because loose-fill cellulose settles over time, it must be installed to its predicted settled density to achieve its R-value. R-Value is the standard for measuring insulation performance.At 3.6 to 3.8 per inch cellulose insulation is considerably better than most mineral fiber blowing wools. Nevertheless, r-value is only one factor to consider, energy savings, air nfiltration and health considerations are a few more that must be taken into account.

On the first hand, actual buildings regularly show that cellulose-insulated buildings may use 20% to 40% less energy than buildings with fiber glass, even if the r-value of the insulation in the walls and ceilings is identical. On the other hand, when cellulose is pneumatically installed it takes on almost liquid-like properties that let it flow into cavities and around obstructions to completely fill walls and seal every crack and seam. No other fiber glass or rock wool material duplicates this action. Liquid-applied foam plastics do, but they cost much more than cellulose

Lastly, a health consideration is another good characteristic of cellulose insulation. Unlike most fiberglass batts, cellulose insulation does not have formaldehyde-based binders that can be harmful to installers and offgas once installed. Fiberglass fibers are friable and can easily become airborne, particularly during installation.These fibers can be inhaled, and some health experts claim that this particulate matter is carcinogenic.

Benefits

• It offers more heat transfer resistance per inch than other fiber insulation materials.
• It seals the home against air infiltration better than other fiber insulations.
  • Productively recycles a waste product that presents communities with a serious disposal problem.
  • Saves more energy when the energy required making the material, “embodied energy”, is figured into total energy savings.
  • Makes homes safer by slowing the spread of fire.

Limitations

Cellulose insulation can hold moisture; repeated wetting and drying could cause the borate treatment to leach out and mold to grow.

Maintenance

Any insulation type will have problems if excessive moisture is allowed into the wall cavity. In this sense, the number one priority should be to eliminate moisture issues before considering the insulation. In other words, if wall cavities are kept dry, there should be no need for maintenance

LEED Credits