Reducing Urban Heat Islands
Compendium of Strategies
Cool Pavements
¦Hi

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Acknowledgements
Reducing Urban Heat Islands: Compendiu m of Strategies describes the
causes and impacts of summertime urban heat islands and promotes
strategies for lowering temperatures in U.S. communities. This compendium
was developed by the Climate Protection Partnership Division in the U.S.
Environmental Protection Agency's Office of Atmospheric Programs. Eva
Wong managed its overall development. Kathleen Hogan, Julie Rosenberg,
Neelam R. Patel, and Andrea Denny provided editorial support. Numerous
EPA staff in offices throughout the Agency contributed content and
provided reviews. Subject area experts from other organizations around the
United States and Canada also committed their time to provide technical
feedback.
Under contracts 68-W-02-029 and EP-C-06-003, Perrin Quarles Associates,
Inc. provided technical and administrative support for the entire
compendium, and Eastern Research Group, Inc. provided graphics and
production services.
For the Cool Pavements chapter, Cambridge Systematics, Inc. provided
support in preparing a June 2005 draft report on cool pavements under
contract to EPA as part of EPA's Heat Island Reduction Initiative.
Experts who helped shape this chapter include: Bruce Ferguson, Kim Fisher,
Jay Golden, Lisa Hair, Liv Haselbach, David Hitchcock, Kamil Kaloush, Mel
Pomerantz, Nam Tran, and Don Waye.
Suggested Citation: U.S. Environmental Protection Agency. 2012. "Cool
Pavements." In: Reducing Urban Heat Islands: Compendium of Strategies.
Draft, https://www.epa.gov/heat-islands/heat-island-compendium.

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Contents
Cool Pavements	1
1.	How It Works	3
1.1	Solar Energy	5
1.2	Solar Reflectance (Albedo)	5
1.3	Thermal Emittance	6
1.4	Permeability	8
1.5	Other Factors to Consider	9
1.6Temperature Effects	10
2.	Potential Cool Pavement Types	11
3.	Benefits and Costs	23
3.1	Benefits	23
3.2	Costs	25
3.3	Life-Cycle Cost and Environmental Impact Considerations	26
4.	Cool Pavement Initiatives	27
5.	Resources	31
Endnotes	32

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Cool Pavements
Cool pavements refer to a range of
established and emerging materials.
These pavement technologies tend to
store less heat and may have lower surface
temperatures compared with conventional
products. They can help address the prob-
lem of urban heat islands, which result in
part from the increased temperatures of
paved surfaces in a city or suburb. Commu-
nities are exploring these pavements as part
of their heat island reduction efforts.
Conventional pavements in the United States
are impervious concrete* and asphalt, which
can reach peak summertime surface tem-
peratures of 120-150°F (48-67°C).2 These
surfaces can transfer heat downward to be
stored in the pavement subsurface, where it
is re-released as heat at night. The warmer
daytime surface temperatures also can heat
stormwater as it runs off the pavement into
local waterways. These effects contribute to
urban heat islands (especially at nighttime)
and impair water quality.
In many U.S. cities, pavements represent the largest
percentage of a community's land cover, compared
with roof and vegetated surfaces. As part of EPA's
Urban Heat Island Pilot Project, Lawrence Berkeley
National Laboratory (LBNL) conducted a series of
urban fabric analyses that provide baseline data on
land use and land use cover, including paved sur-
faces for the pilot program cities.1 Figure 1 shows
the percent of paved surfaces in four of these
urban areas, as viewed from below the tree canopy.
The data are from 1998 through 2002, depending
on the city. Paved areas, which can absorb and
store much of the sun's energy contributing to the
urban heat island effect, accounted for nearly 30 to
45 percent of land cover.
Figure 1: Paved Surface Statistics for Four U.S. Cities
Salt Lake City
0 5 10 15 20 25 30 35 40 45 50
Percent Coverage
* When new, concrete has a high solar reflectance and generally is considered a cool pavement; however, it loses reflectance over time, as discussed in
Section 1.2.
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Figure 2: Conventional Pavement Temperatures
This picture of Phoenix, Arizona, in the summer shows a variety of conventional pavements that reached
temperatures up to 150°F (67°C).
Defining Cool Pavements
Unlike a "cool" roof, a "cool" pavement has no standard, official definition. Until
recently, the term has mainly referred to reflective pavements that help lower sur-
face temperatures and reduce the amount of heat absorbed into the pavement.
With the growing interest and application of permeable pavements—which allow
air, water, and water vapor into the voids of a pavement, keeping the material cool
when moist—some practitioners have expanded the definition of cool pavements to
include permeable pavements as well. Ongoing permeable pavement research is im-
portant because these systems, compared with conventional pavement systems, react
differently and lead to different environmental impacts. Further, as we understand
better how pavements affect urban climates and develop newer, more environmen-
tal technologies, additional technologies that use a variety of techniques to remain
cooler are likely to emerge.
As concerns about elevated summertime
temperatures rise, researchers and policy-
makers are directing more attention to the
impact pavements have on local and global
climates. This chapter discusses:
•	Pavement properties and how they
can be modified to reduce urban heat
islands
•	Conditions that affect pavement proper-
ties
•	Potential cool pavement technologies
•	Cool pavement benefits and costs
•	Cool pavement initiatives and research
efforts
•	Resources for further information.
Given that cool pavements are an evolv-
ing technology and much is still unknown
about them, this compendium presents
basic information to give readers a general
understanding of cool pavement issues
to consider; it is not intended to provide
decision guidance to communities. Deci-
sion-makers can work with local experts
to obtain location-specific information to
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Why Have Communities Promoted Cool Roofs More Than Cool
Pavements?
A few decades ago when the concept of using cool roofs and pavements emerged,
researchers focused on radiative properties—surface solar reflectance and thermal
emittance—associated with these technologies. Scientists, engineers, and others
worked together through the standards-development organization ASTM Interna-
tional to create test standards for these properties that could apply to both roofs and
pavements. (See Section 4.1.) While researchers, industry, and supporters of energy
efficiency have helped advance cool roofing into the market, cool pavement has
lagged behind. Three factors, which differentiate pavements from roofs, may contrib-
ute to this difference:
1.	Pavements are complex. Conditions that affect pavement temperatures, but not
roofing materials, include: (a) dirtying and wearing away of a surface due to daily
foot and vehicle traffic, affecting pavement surface properties; (b) convection
due to traffic movement over the pavement; and (c) shading caused by people
and cars, vegetation, and neighboring structures and buildings. These factors are
discussed in Sections 1.2 and 2.
2.	Pavement temperatures are affected by radiative and thermal characteristics, un-
like cool roofs, where radiative properties are the main concern. This is discussed
in Section 1.3.
3.	Pavements serve a variety of functions throughout an urban area. Their uses
range from walking trails to heavily trafficked highways (unlike cool roofs, which
generally perform the same function and are off-the-shelf products). Different
materials and specifications are needed for these different uses, and pavements
are often individually specified, making it difficult to define or label a cool pave-
ment.
further guide them in the pavement selec-
tion process. EPA expects that significant
ongoing research efforts will expand the
opportunities for updating existing technol-
ogies and implementing new approaches
to cool pavements. At the end of Sections 4
and 5 in this document, organizations and
resources with the most recent information
are listed. Communities will also continue
to implement new demonstration projects
and cool pavement initiatives. EPA intends
to provide updated information as it be-
comes available. Please visit .
1. How It Works
Understanding how cool pavements work
requires knowing how solar energy heats
pavements and how pavement influences
the air above it. Properties such as solar
energy, solar reflectance, material heat
capacities, surface roughness, heat transfer
rates, thermal emittance, and permeability
affect pavement temperatures.
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Reducing or Shading Pavements
Some efforts have emerged that focus on reducing the need to pave, particularly over
vegetated areas that provide many benefits, including lowering surface and air tem-
peratures. Communities have used various options to reduce the amount of paved
surface areas, such as lowering parking space requirements, connecting parking and
mass transit services, allowing for narrower street widths, or providing incentives for
multi-level parking versus surface lots.3
Concerned communities that move forward with paving often shade it with vegeta-
tion. The "Trees and Vegetation" chapter discusses the use of measures such as park-
ing lot shading ordinances as part of a heat island mitigation strategy.
Another option some local governments and private firms are considering involves
installing canopies that incorporate solar panels in parking lots. These photovoltaic
canopies shade surfaces from incoming solar energy and generate electricity that can
help power nearby buildings or provide energy for plug-in electric vehicles.4
For more information on urban planning and design approaches to minimize paved
surfaces, see , and for information on vegetated sur-
faces, see the "Trees and Vegetation" chapter of this compendium.
Figure 3: Solar Energy versus Wavelength Reaching Earth's Surface on a Typical Clear Summer Day
ultraviolet — visible
infrared
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600
Wavelength (in nanometers)
Solar energy intensity varies over wavelengths from about 250 to 2,500 nanometers. Figure 3 demonstrates this
variation, using a normalized measure of solar intensity on a scale of zero (minimum) to one (maximum). Currently,
reflective pavements are light colored and primarily reflect visible wavelengths. However, similar to trends in the
roofing market, researchers are exploring pavement products that appear dark but reflect energy in the near-infrared
spectrum.5 (See the "Cool Roofs" chapter of the compendium for more information.)
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1.1 Solar Energy
Solar energy is composed of ultraviolet
(UV) rays, visible light, and infrared en-
ergy, each reaching the Earth in different
percentages: 5 percent of solar energy is
in the UV spectrum, including the type of
rays responsible for sunburn; 43 percent of
solar energy is visible light, in colors rang-
ing from violet to red; and the remaining
52 percent of solar energy is infrared, felt
as heat. Energy in all of these wavelengths
contributes to urban heat island formation.
Figure 3 shows the typical solar energy
that reaches the Earth's surface on a clear
summer day.
1.2 Solar Reflectance (Albedo)
Solar reflectance, or albedo, is the per-
centage of solar energy reflected by a
surface. Most research on cool pavements
has focused on this property, and it is the
main determinant of a material's maximum
surface temperature.6 Albedo also affects
pavement temperatures below the surface,
because less heat is available at the sur-
face to then be transferred into the pave-
ment. Researchers, engineers, and industry
have collaborated to develop methods to
determine solar reflectance by measuring
how well a material reflects energy at each
wavelength, then calculating the weighted
average of these values.* (See Table 1 on
page 7.)
Conventional paving materials such as as-
phalt and concrete have solar reflectances of
5 to 40 percent, which means they absorb
95 to 60 percent of the energy reaching
them instead of reflecting it into the atmo-
sphere. (See Figure 4.) However, as Figure 4
also shows, these values depend on age and
Most existing research on cool pave-
ments focuses on solar reflectance,
which is the primary determinant of
a material's maximum surface tem-
perature. Many opportunities exist to
improve this property in pavements.
(See Table 2, beginning on page 15.)
Figure 4: Typical Solar Reflectance of
Conventional Asphalt and Concrete Pavements
over Time
45 i
40
= 35
Concrete pavements
(U
u
c 30
u
C
IV
« 20
o
" 15
Asphalt pavements
10
5
0
2
3
4
5
6
Due to weathering and the accumulation of dirt, the
solar reflectances of conventional asphalt and concrete
tend to change over time. Asphalt consists largely of
petroleum derivatives as a binder mixed with sand or
stone aggregate. Asphalt tends to lighten as the binder
oxidizes and more aggregate is exposed through wear.
Concrete also uses sand and stone aggregate, but in
contrast to asphalt, typically uses Portland cement as
a binder.7 Foot and vehicle traffic generally dirty the
cement causing it to darken over time.
material, and thus usually change over time.
Figure 5 shows how changing only albedo
can significantly alter surface temperatures.
Although researchers, including those at
LBNL, have made light-colored pavements
with solar reflectances greater than 75 per-
cent,8 these high albedo pavements do not
have widespread commercial availability.
* Albedo is typically measured on a scale of zero to one. For this compendium, albedo is given as a percentage, so an albedo of 0.05 corresponds to a solar
reflectance of 5 percent. The "solar reflectance index" is a value on a scale of zero to 100 that incorporates both solar reflectance and thermal emittance in
a single measure to represent a material's temperature in the sun. (See Table 1 on page 7 or further explanation.)
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Figure 5: The Effect of Albedo on Surface Temperature
Albedo alone can significantly influence surface temperature, with the white stripe on the brick wall about 5-10°F
(3-5vC) cooler than the surrounding, darker areas.
1.3 Thermal Emittance
A material's thermal emittance determines
how much heat it will radiate per unit area
at a given temperature, that is, how readily a
surface sheds heat. Any surface exposed to
radiant energy will heat up until it reaches
thermal equilibrium (i.e., gives off as much
heat as it receives). When exposed to sun-
light, a surface with high emittance will
reach thermal equilibrium at a lower tem-
perature than a surface with low emittance,
because the high-emittance surface gives
off its heat more readily. As noted in Table
1 on page 7, ASTM methods can be used to
measure this property.
Thermal emittance plays a role in determin-
ing a material's contribution to urban heat
islands. Research from 2007 suggests albedo
and emittance have the greatest influence
on determining how a conventional pave-
ment cools down or heats up, with albedo
having a large impact on maximum sur-
face temperatures, and emittance affecting
minimum temperatures.9 Although thermal
emittance is an important property, there
are only limited options to adopt cool pave-
ment practices that modify it because most
pavement materials inherently have high
emittance values.10
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Standards for Measuring Solar Reflectance and Thermal
Emittance
To evaluate how "cool" a specific product is, ASTM International has validated labo-
ratory and field tests and calculations to measure solar reflectance, thermal emit-
tance, and the solar reflectance index, which was developed to try to capture the
effects of both reflectance and emittance in one number. (See Table 1 below.) Labo-
ratory measurements are typically used to examine the properties of new material
samples, while field measurements evaluate how well a material has withstood the
test of time, weather, and dirt.
The final method listed in Table 1 is not an actual test but a way to calculate the
"solar reflectance index" or SRI. The SRI is a value that incorporates both solar reflec-
tance and thermal emittance in a single value to represent a material's temperature
in the sun. This index measures how hot a surface would get compared to a standard
black and a standard white surface. In physical terms, this scenario is like laying a
pavement material next to a black surface and a white surface and measuring the
temperatures of all three surfaces in the sun. The SRI is a value between zero (as hot
as a black surface) and 100 (as cool as a white surface).
Table 1: Solar Reflectance and EmittanceTest Methods
Property
Test Method
Equipment Used
Test Location
Solar reflectance
ASTM E 903 - Standard Test Method
for Solar Absorbance, Reflectance,
and Transmittance of Materials Using
Integrating Spheres.
Integrating sphere spectro-
photometer
Laboratory
Solar reflectance
ASTM C 1549 - Standard Test Method
for Determination of Solar Reflectance
Near Ambient Temperature Using a
Portable Solar Reflectometer
Portable solar reflectometer
Laboratory or
field
Solar reflectance
ASTM E 1918 - Standard Test Method
for Measuring Solar Reflectance of
Horizontal and Low-Sloped Surfaces in
the Field
Pyranometer
Field
Total emittance
ASTM E408-71 - Standard Test Methods
for Total Normal Emittance of Surfaces
Using Inspection-Meter Techniques
Portable, inspection-meter
instruments
Laboratory or
field
Solar reflectance
index
ASTM E 1980 - Standard Practice for
Calculating Solar Reflectance Index of
Horizontal and Low-Sloped Opaque
Surfaces
None (calculation)

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Pavement Surface arid Subsurface Temperatures
This chapter mainly focuses on pavement surface temperatures, as most of the cited
studies focus on the surface layer. For conventional pavements, most of the impacts
at the surface tend to affect the subsurface similarly For example, conventional
pavements with high solar reflectance generally reduce surface and subsurface tem-
peratures, as less heat is available at the surface to absorb into the pavement. How-
ever, permeable surfaces react differently. When dry, permeable pavement surface
temperatures may be higher than their impermeable equivalent; but preliminary
research shows that the subsurface generally is similar to or even cooler than the
conventional equivalent, because the permeable layer reduces heat transfer below.11
More information on subsurface heat transfer is needed to understand the potential
heat island impacts because the heat stored in the subsurface may significantly af-
fect nighttime temperature. Still, many complex interactions take place between the
surface and subsurface layers. These interactions are either briefly covered in Section
1.5 or beyond the scope of this chapter.
1.4 Permeability
Although originally designed for storm-
water control, permeable pavements are
emerging as a potential cool pavement.
These pavements allow air, water, and
water vapor into the voids of the pavement.
Permeable pavement technologies include
porous asphalt applications, pervious con-
crete applications, permeable pavers, and
grid pavements. To achieve both perme-
ability objectives and structural needs for
expected traffic load, these permeable
pavements benefit from proper design and
installation.12
When wet, these pavements can lower tem-
peratures through evaporative cooling. The
water passes through the voids and into the
soil or supporting materials below. (See Fig-
ure 6.) Moisture within the pavement struc-
ture evaporates as the surface heats, thus
drawing heat out of the pavement, similar
to evaporative cooling from vegetated land
cover. Some permeable pavement systems
Figure 6: Permeable versus
Conventional Asphalt
Permeable asphalt (foreground) allows water to
drain from the surface and into the voids in the
pavement, unlike conventional asphalt (mid- and
background).
contain grass or low-lying vegetation, which
can stay particularly cool because the sur-
face temperature of well-hydrated vegeta-
tion typically is lower than the ambient air
temperature.
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When dry, the extent to which permeable
pavements can influence temperatures is
more complex and uncertain. For example,
the larger air voids in permeable pave-
ments increase the available surface area.
These conditions may limit heat transfer
to the lower pavement structure and soils,
keeping heat at the pavement's surface
(and increasing daytime surface tempera-
tures), but reducing bulk heat storage (re-
ducing release of heat at nighttime).13 The
larger surface area also may help increase
air movement—convection—over the pave-
ment, transferring heat from the pavement
to the air. Overall, the limited transfer of
heat to the pavement subsurface layers
would reduce the release of heat during
the nighttime. Release of stored heat from
urban materials is a significant contributor
to the nighttime heat island experienced in
many cities.
More research is needed to better under-
stand the impacts of permeable pavement
on air temperatures and urban heat island
conditions. Given the complexity of these
cooling mechanisms, and the wide range of
conditions under which these pavements
function, further field testing and valida-
tion would help to quantify and clarify the
range of impacts and benefits of permeable
pavements on urban climates.
1.5 Other Factors to Consider
Pavement temperatures depend on a series
of factors. Reflective pavements increase
the albedo of the surface to limit heat gain,
whereas permeable pavements permit
evaporative cooling when the pavement is
moist, helping to keep it cool. As shown in
Table 2 (beginning on page 15), however,
actual conditions alter pavement proper-
ties, resulting in pavements that may not be
"cool" under all circumstances. This chapter
presents these issues for communities to
consider when making pavement choices.
Water Retentive Pavements
and Water Sprinkling in
Japan
Some cities in Japan, such as
Tokyo and Osaka, are testing the
effectiveness of water retentive
pavements as part of using
permeable pavements to reduce
the heat island effect. These porous
pavements can be asphalt or
concrete-based and have a sublayer
that consists of water retentive
materials that absorb moisture and
then evaporate it through capillary
action when the pavement heats
up. Some of these systems involve
underground water piping to
ensure the pavement stays moist.
Researchers have also tested water
sprinkling, where pavements are
sprayed with water during the
day. Some cities have used treated
wastewater. Results to date are
promising, as both water retentive
pavements and water sprinkling have
been effective in keeping pavement
temperatures low.14
Besides solar reflectance, emittance, and
permeability, other properties and factors
influence how readily pavements absorb or
lose heat.
• Convection. Pavement transfers heat to
the air through convection as air moves
over the warm pavement. The rate of
convection depends on the velocity
and temperature of the air passing over
the surface, pavement roughness, and
the total surface area of the pavement
exposed to air. Some permeable pave-
ments have rougher surfaces than con-
ventional pavements, which increases
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their effective surface area and creates
air turbulence over the pavement. While
this roughness can increase convection
and cooling, it may also reduce a sur-
face's net solar reflectance.
•	Thermal Conductivity. Pavement with
low thermal conductivity may heat up
at the surface but will not transfer that
heat throughout the other pavement
layers as quickly as pavement with
higher conductivity.
•	Heat Capacity. Many artificial materi-
als, such as pavement, can store more
heat than natural materials, such as dry
soil and sand. As a result, built-up areas
typically capture more of the sun's
energy—sometimes retaining twice as
much as their rural surroundings dur-
ing daytime.15 The higher heat capacity
of conventional urban materials con-
tributes to heat islands at night, when
materials in urban areas release the
stored heat.
•	Thickness. The thickness of a pave-
ment also influences how much heat it
will store, with thicker pavements stor-
ing more heat.16
•	Urban Geometry. The dimensions and
spacing of buildings within a city, or ur-
ban geometry, can influence how much
heat pavements and other infrastruc-
ture absorb. For example, tall buildings
along narrow streets create an "urban
canyon." (See Figure 7.) This canyon ef-
fect can limit heat gain to the pavement
during the day, when the buildings pro-
vide shade. But these same buildings
may also absorb and trap the heat that
is reflected and emitted by the pave-
ment, which prevents the heat from
escaping the city and exacerbates the
heat island effect, especially at night.
The overall impact of the urban canyon
effect will depend on how a specific
city is laid out, the latitude, the time of
year, and other factors.
More research is needed to determine the
exact impacts these properties have on
pavement temperatures and the urban heat
island effect.
1.6Temperature Effects
Solar reflectance and thermal emittance
have noticeable effects on surface tempera-
tures, as discussed in Sections 1.2 and 1.3.
Depending on moisture availability, perme-
able pavements also can lower pavement
temperatures. Other properties, as noted in
Section 1.5, also influence pavement sur-
face and subsurface temperatures through
a variety of complex interactions. In gener-
al, lower surface temperatures will result in
lower near-surface air temperatures, with
the effect decreasing as one moves farther
away from the surface due to air mixing.
Location-specific conditions, such as wind
speed and cloud cover, can greatly influ-
ence surface and air temperatures.
Currently, few studies have measured the
role pavements play in creating urban heat
islands, or the impact cooler pavements
can have on reducing the heat island ef-
fect. Researchers at LBNL, however, have
estimated that every 10 percent increase
in solar reflectance could decrease sur-
face temperatures by 7°F (4°C). Further,
they predicted that if pavement reflec-
tance throughout a city were increased
from 10 percent to 35 percent, the air
temperature could potentially be reduced
by 1°F (0.6°C).17 Earlier research analyzed
a combination of mitigation measures in
the Los Angeles area, including pavement
and roofing solar reflectance changes, and
increased use of trees and vegetation. The
study identified a 1.5°F (0.8°C) temperature
improvement from the albedo changes.18 A
subsequent report analyzed the monetary
benefits associated with these temperature
improvements, and estimated the indirect
benefits (energy savings and smog reduc-
tions) of the temperature reduction in Los
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Figure 7: Urban Canyons
The row of three- and four-story townhouses on the left creates a relatively modest urban canyon, while the
skyscrapers on the right have a more pronounced effect.
Angeles from pavement albedo improve-
ments would be more than $90 million per
year (in 1998 dollars).19
2. Potential Cool Pavement Types
Current cool pavements are those that have
increased solar reflectance or that use a
permeable material. Some of these pave-
ments have long been established—such
as conventional concrete, which initially
has a high solar reflectance. Others are
emerging—such as microsurfacing, which
is a thin sealing layer used for mainte-
nance.20 Some pavement applications are
for new construction, while others are used
for maintenance or rehabilitation. Not all
applications will be equally suited to all
uses. Some are best for light traffic areas,
for example. Further, depending on local
conditions—such as available materials,
labor costs, and experience with different
applications—certain pavements may not
be cost effective or feasible.
Generally, decision-makers choose pav-
ing materials based on the function they
serve. Figure 8 shows the proportions of
pavement used for different purposes in
four cities. Parking lots typically make up
a large portion of the paved surfaces in
urban areas. All current cool pavement
technologies can be applied to parking
lots, which may explain why many re-
search projects have been and are being
conducted on them.
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Figure 8: Percentage of Pavement Area by Type
of Use21
= 30
I Roads
i Parking
Sidewalks
l Other
Sacramento Chicago Salt Lake Houston
City	i
Cities	I
LBNL conducted a paved surface analysis in four cities,
dividing the uses into four general categories. Roads
and parking lots make up the majority of paved areas.
Below are brief descriptions of potential
cool pavements and their typical uses:
•	Conventional asphalt pavements,
which consist of an asphalt binder
mixed with aggregate, can be modified
with high albedo materials or treated
after installation to raise reflectance.
This material has been applied for de-
cades in a wide range of functions from
parking lots to highways.
•	Conventional concrete pavements,
made by mixing Portland cement,
water, and aggregate, can be used in a
wide range of applications including
trails, roads, and parking lots.
•	Other reflective pavements, made
from a variety of materials, are mostly
used for low-traffic areas, such as side-
walks, trails, and parking lots. Exam-
ples include:
-	Resin based pavements, which
use clear tree resins in place of
petroleum-based elements to bind
an aggregate
-	Colored asphalt and colored con-
crete, with added pigments or seals
to increase reflectance
Nonvegetated permeable pavements
contain voids and are designed to allow
water to drain through the surface into
the sublayers and ground below. These
materials can have the same structural
integrity as conventional pavements.
For example, some forms of porous
pavements, such as open-graded fric-
tion course (OGFC) asphalt pave-
ments, have been in use for decades
to improve roadway friction in wet
weather.22 Recently, rubberized asphalt
has been used on roads and highways
to reduce noise, and pervious concrete
applications are being studied for road-
way use. For some permeable pavement
options, the typical use may be for
lower traffic areas such as parking lots,
alleys, or trails. Examples of nonveg-
etated permeable pavements include:
-	Porous asphalt
-	Rubberized asphalt, made by mix-
ing shredded rubber into asphalt
-	Pervious concrete
-	Brick or block pavers, are gener-
ally made from clay or concrete,
and filled with rocks, gravel, or soil;
also available in a variety of colors
and finishes designed to increase
reflectance
Vegetated permeable pavements,
such as grass pavers and concrete grid
pavers, use plastic, metal, or concrete
lattices for support and allow grass or
other vegetation to grow in the inter-
stices. Although the structural integrity
can support vehicle weights compa-
rable to conventional pavements, these
materials are most often used in areas
where lower traffic volumes would
minimize damage to the vegetation,
such as alleys, parking lots, and trails,
and they may be best suited to climates
with adequate summer moisture.
12
REDUCING URBAN HEAT ISLANDS - DRAFT

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•	Chip seals consist of aggregate bound
in liquid asphalt, and are often used to
resurface low-volume asphalt roads and
sometimes highways.
•	Whitetopping is a layer of concrete
greater than 4 inches (10 cm) thick,
often containing fibers for added
strength. Typical applications include
resurfacing road segments, intersec-
tions, and parking lots.
•	Ultra-thin whitetopping is similar
to whitetopping and can be used in
the same applications, but is only 2-4
inches (5-10 cm) thick.
•	Microsurfacing is a thin sealing layer
used for road maintenance. Light-col-
ored materials can be used to increase
the solar reflectance of asphalt. Re-
searchers recently applied light-colored
microsurfacing material that consisted
of cement, sand, other fillers, and a liq-
uid blend of emulsified polymer resin,
and found the solar reflectance to be
comparable to that of new concrete.23
Table 2, beginning on page 15, provides
summary information for decision-makers
to consider. It is meant as a preliminary
guide, as more research and location-
specific data are needed. Table 2 includes
the following:
•	A brief description of the technology
•	The properties associated with it
•	The potential impacts on pavement and
air temperatures
•	Issues to consider
•	Target functions.
Regarding impacts, the "+" sign indicates a
positive effect; for example, a technology
generally results in lower pavement tem-
peratures. A signals a negative effect; for
example, a technology may lead to higher
air temperatures in certain conditions.
Slag and Fly Ash Cement
Slag and fly ash are sometimes added
to concrete to improve its perfor-
mance. Slag is a byproduct of pro-
cessing iron ore that can be ground
to produce cement, and fly ash is
a byproduct of coal combustion.24
These materials can make concrete
stronger, more resistant to aggressive
chemicals, and simpler to place. These
cements also reduce material costs
and avoid sending wastes to landfills.
A key heat island benefit of slag is its
lighter color, which can increase the
reflectivity of the finished pavement.
A 2007 study measured a solar reflec-
tance of almost 60 percent for cement
with slag, versus about 35 percent
for a conventional concrete mix.25 In
contrast, fly ash tended to darken con-
crete unless counterbalanced, such as
by added slag. However, substituting
fly ash for a portion of the Portland
cement reduces greenhouse gases and
other emissions associated with pro-
ducing Portland cement. Because of
such benefits, California's Department
of Transportation typically requires
use of 25 percent fly ash in cement
mixtures.26
Effects described in the table do not con-
sider magnitude, which may be influenced
by local conditions. Therefore, this infor-
mation is not intended for comparison.
The cool pavement technologies in Table
2 can have positive and negative impacts,
depending on actual conditions such as
moisture availability and urban design.
The points listed under "issues and consid-
erations" further illustrate the complexity
associated with cool pavements. These bul-
lets only discuss concerns related to urban
COOL PAVEMENTS -
DRAFT
13

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heat islands and do not include other local
factors or priorities that decision-makers
generally consider when making pavement
choices.
Despite its limitations, Table 2 can be used
as a starting point. For example, using
Table 2, a city that generally uses asphalt
paving can identify alternative cool as-
phalt technologies for functions from bike
trails to roads. They can also discern that
high albedo pavements may be most effec-
tive in open areas, not surrounded by tall
buildings. Most communities will further
investigate the benefits and costs of the
technology, as discussed in Section 3, and
location-specific factors, such as political
acceptance and experience with the tech-
nology.
Filling in the Gaps
As more researchers and communi-
ties install cool pavement technolo-
gies, more data will be generated and
shared in forums such as the Trans-
portation Research Board Subcom-
mittee on Paving Materials and the
Urban Climate. (See Section 4 of this
chapter.)
14
REDUCING URBAN HEAT ISLANDS - DRAFT

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Table 2: Properties that Influence Pavement Temperatures—Impacts and Applications
NEW CONSTRUCTION
Pavement Type
Description of
Properties to Consider
Pavement Temperature
Urban Climate Impacts
Issues and
Target Use

Technology

Impacts

Considerations

Reflective Pavement Options
Asphalt pavement.
Asphalt pavements
• Solar reflectance.
+ Lowers pavement
+ Can contribute to
• Solar reflectance
• Can be used in all
modified with high
consist of an asphalt
which initially may
temperature because
lower air tempera-
increases overtime.
applications, such as
albedo materials or
binder mixed with sand
be 5%, can increase
more of the sun's
tures day and night.
and conventional
trails and roads.
treated after installation
or stone, referred to as
to 15-20% as con-
energy is reflected
although air tempera-
asphalt may reach a
• May be most effec-
to raise albedo.
aggregate.
ventional asphalt
away, and there is less
tures are not directly
reflectance of 20%
tive when paving


ages.27
heat at the surface to
related to surface
after seven years.29
large, exposed areas


• Using light-colored
absorb into the pave-
temperatures and
(See Section 1.2.)
such as parking lots.


aggregate, color pig-
ment.
many complicating
• Urban geometry.



ments, or sealants.

factors are involved.28
in particular urban



the reflectance of

- Reflected heat can be
canyons, influences



conventional asphalt

absorbed by the sides
the impact reflective



can be increased.

of surrounding build-
pavements have on



• Maintenance ap-

ings warming the in-
the urban climate.



plications such as

terior of the building




chip seals also can

and contributing to




increase solar reflec-

the nighttime urban




tance. (See below.)

heat island effect.




• Urban geometry can

due to the additional




influence the effect

heat that needs to be




of high albedo pave-

released from urban




ments.

infrastructure.

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Table 2: Properties that Influence Pavement Temperatures—Impacts and Applications (continued)
NEW CONSTRUCTION (continued)
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PavementType
Description of
Properties to Consider
Pavement Temperature
Urban Climate Impacts
Issues and
Target Use

Technology

Impacts

Considerations

Reflective Pavement Options (continued)
Concrete:
Portland cement mixed
• Initial solar reflec-
+ Lowers pavement
+ Can contribute to
• Solar reflectance
• Can be used in all
• Conventional
with water and ag-
tance can be 40%.
temperature because
lower air tempera-
decreases overtime.
applications, such as
• Modified
gregate. Cured until it is
• This can be raised
more of the sun's
tures day and night.
as soiling from traffic
trails and roads.

strong enough to carry
to more than 70%
energy is reflected
although air tempera-
darkens the surface.
• May be most effec-

traffic.
using white cement
away,and there is less
tures are not directly
• Conventional con-
tive when paving


instead of gray ce-
heat at the surface to
related to surface
crete may reach a
large, exposed areas.


ment mixtures.30
absorb into the pave-
temperatures and
reflectance of 25%
such as parking lots.


• Urban geometry can
ment.
many complicating
after 5 years.31 (See



influence the effect

factors are involved.
Section 1.2.)



of high-albedo pave-

- Reflected heat can be
• Urban geometry.



ments.

absorbed by the sides
in particular urban





of surrounding build-
canyons, influences





ings warming the in-
the impact reflective





terior of the building
pavements have on





and contributing to
the urban climate.





the nighttime urban






heat island effect.






due to the additional






heat that needs to be






released from urban






infrastructure.

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Table 2: Properties that Influence Pavement Temperatures—Impacts and Applications (continued)
NEW CONSTRUCTION (continued)
PavementType
Description of
Properties to Consider
Pavement Temperature
Urban Climate Impacts
Issues and
Target Use

Technology

Impacts

Considerations

Reflective Pavement Options (continued)
Other reflective
• Resin based pave-
• These alternative
+ Lowers pavement
+ Can contribute to
• As with concrete.
• Use depends on the
pavements:
ments use clear
pavements will have
temperature because
lower air tempera-
solar reflectance may
pavement applica-
• Resin based
colored tree resins in
varying solar reflec-
more of the sun's
tures day and night.
decrease overtime
tion. In general.
• Colored asphalt
place of cement to
tances based on the
energy is reflected
although air tempera-
as soiling from traffic
these alternative
• Colored concrete
bind the aggregate.
materials used to
away,and there is less
tures are not directly
makes the pavement
pavements are used

thus albedo is mainly
construct them.
heat at the surface
related to surface
darker and the sur-
for low-traffic areas.

determined by ag-
• Urban geometry can
to absorb into the
temperatures and
face wears away.
such as sidewalks.

gregate color.
influence the effect
pavement.
many complicating
• Urban geometry.
trails, and parking

• Colored asphalt or
high-albedo pave-

factors are involved.
particularly urban
lots.

concrete involve pig-
ments have.

- Reflected heat can be
canyons, influences
• May be most effec-

ments or seals that


absorbed by the sides
the impact high-
tive when paving

are colored and may


of surrounding build-
albedo pavements
large, exposed areas.

be more reflective


ings warming the in-
have on the urban
such as parking lots.

than the conven-


terior of the building
climate.


tional equivalent.


and contributing to



These can be applied


the nighttime urban



when new or during


heat island effect.



maintenance.


due to the additional






heat that needs to be






released from urban






infrastructure.

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& Table 2: Properties that Influence Pavement Temperatures—Impacts and Applications (continued)
NEW CONSTRUCTION (continued)
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PavementType
Description of
Properties to Consider
Pavement Temperature
Urban Climate Impacts
Issues and
Target Use

Technology

Impacts

Considerations

Permeable Pavement Options
Nonvegetated perme-
• Porous asphalt has
• Provides cool-
+ When wet, lowers
+ When moist, can
• Cooling mecha-
• Structurally, avail-
able pavements
more voids than con-
ing through
pavement tempera-
contribute to lower
nism depends on
able for any use.

ventional asphalt to
evaporation.
ture through evapora-
air temperatures day
available moisture.
Rubberized asphalt

allow water to drain
• Solar reflectance of
tive cooling.
and night, through
Supplemental water-
and open-graded

through the surface
these materials de-
-When dry, may be hot
evaporative cooling.
ing may keep them
friction course

into the base.
pends on individual
at the surface, but
although air tempera-
cooler.35
asphalt are used on

• Rubberized asphalt.
materials (e.g., gravel
subsurface generally
tures are not directly
• Void structure may
roads and highways

or crumb rubber, in-
may be white and
will be same tempera-
related to surface
aid in insulating the
and pervious con-

volves mixing shred-
very reflective). In
ture as nonpermeable
temperatures and
subsurface from heat
crete actively being

ded rubber into
general, permeable
equivalent.
many complicating
absorption.
considered.

asphalt.This material
pavements may be

factors are involved.
• More research
• Technologies often

is generally used to
less reflective than

-When dry, can
needed to deter-
applied to lower

reduce noise.
their nonpermeable

contribute to higher
mine permeable
traffic areas, such as

• Other porous
equivalent due to

daytime surface
pavement impacts
parking lots, alleys.

asphalts or open-
the increased surface

temperatures, but
on pavement and air
and trails.

grade course friction
area.33

may not affect or may
temperatures.
• May be best in cli-

surfaces can also be
• Increased convec-

even reduce night-

mates with adequate

used for reducing
tion may help cool

time air temperatures.

moisture during the

noise.32
the pavement due

although air tempera-

summer.


to increased surface

tures are not directly




area.34

related to surface






temperatures and






many complicating






factors are involved.

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Table 2: Properties that Influence Pavement Temperatures—Impacts and Applications (continued)
NEW CONSTRUCTION (continued)
PavementType
Description of
Properties to Consider
Pavement Temperature
Urban Climate Impacts
Issues and
Target Use

Technology

Impacts

Considerations

Permeable Pavement Options (continued)
Nonvegetated
• Pervious concrete
(see prior page)
(see prior page)
(see prior page)
(see prior page)
(see prior page)
permeable pavements
has more voids than





(continued)
conventional con-






crete to allow water






to drain through






the surface into the






base.






• Brick or block pavers






are generally made






from clay or concrete






blocks filled with






rocks, gravel, or soil.





Vegetated permeable
• Plastic, metal, or
• Provides cooling
+ Lowers pavement
+ In most conditions
• Cooling mecha-
• Low-traffic areas.
pavements:
concrete lattices
through evapotrans-
temperatures
will contribute to
nism depends on
such as alleys, park-
• Grass pavers
provide support and
piration.
through evapotrans-
lower air tempera-
available moisture.
ing lots, and trails.
• Concrete
allow grass or other
• Sustainability of
piration, particularly
tures day and night.
Supplemental mois-
• May be best in cli-
grid pavers
vegetation to grow
vegetation may vary
when moist.
through evapo-
ture, for example
mates with adequate

in the interstices.
with local conditions.
+ When dry may
transpiration and
watering pavements.
moisture during the



still be cooler than
natural properties of
may keep them
summer.



other pavement
vegetation. Mois-
cooler.35




options due to the
ture availability will
• More research




natural properties of
greatly increase its
needed to determine




vegetation.
effectiveness.
temperature impacts






from vegetated






pavements under






a wide range of






conditions.

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Table 2: Properties that Influence Pavement Temperatures—Impacts and Applications (continued)
MAINTENANCE/REHABILITATION
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PavementType
Description of
Technology
Properties to Consider
Pavement Temperature
Impacts
Urban Climate Impacts
Issues and
Considerations
Target Use
Reflective Pavement Options
Chip seals made with
• Chip seals describe
• Solar reflectance of
+ Lowers pavement sur-
+ Can contribute to
• Solar reflectance
• Chip seals are most
high-albedo aggregate
aggregate used to
chip seals will corre-
face and subsurface
lower air tempera-
decreases overtime.
often used to resur-

resurface low-
late with the albedo
temperature because
tures day and night.
as soiling from traffic
face low-volume

volume asphalt
of the aggregate
more of the sun's
although air tempera-
makes chip seals
asphalt roads.

roads and some-
used. In San Jose, CA,
energy is reflected
tures are not directly
darker.
although highway

times for highway
researchers identi-
away,and there is less
related to surface
• Urban geometry, in
applications also

surfaces.
fied albedo of 20%
heat at the surface
temperatures and
particular urban
exist.


for new chip seals.
to absorb into the
many complicating
canyons, influences
• May be most effec-


which then decline
pavement.
factors are involved.
the impact high-
tive when paving


with age.37

- Reflected heat can be
albedo pavements
large, exposed areas.


• Urban geometry can

absorbed by the sides
have on the urban
such as parking lots.


influence the effect

of surrounding build-
climate.



high-albedo pave-

ings warming the in-




ments have

terior of the building
and contributing to
the urban heat island
effect.

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Table 2: Properties that Influence Pavement Temperatures—Impacts and Applications (continued)
MAINTENANCE/REHABILITATION (continued)
PavementType
Description of
Properties to Consider
Pavement Temperature
Urban Climate Impacts
Issues and
Target Use

Technology

Impacts

Considerations

Reflective Pavement Options (continued)
Whitetopping
• Whitetopping is a
• The solar reflectance
+ Lowers pavement sur-
+ Can contribute to
• Solar reflectance
• Whitetopping and

thick layer (thick-
of whitetopping
face and subsurface
lower air tempera-
decreases overtime.
ultra-thin whitetop-

ness greater than
material can be as
temperature because
tures day and night.
as soiling from traffic
ping are generally

4 inches or 10 cm)
high as concrete.
more of the sun's
although air tempera-
makes whitetopped
used to resurface

of concrete applied
• Urban geometry
energy is reflected
tures are not directly
surfaces darker.
road segments.

over existing asphalt
can influence the
away,and there is less
related to surface
• Urban geometry, in
intersections, and

when resurfacing
effect of high-albedo
heat at the surface
temperatures and
particular urban
parking lots.

or can be applied to
pavements.
to absorb into the
many complicating
canyons, influences
• May be most effec-

new asphalt. It often

pavement.
factors are involved.
the impact high-
tive when paving

contains fibers for


- Reflected heat can be
albedo pavements
large, exposed areas.

added strength.


absorbed by the sides
have on the urban
such as parking lots.

• Ultra-thin whitetop-


of surrounding build-
climate.


ping is generally 2-4


ings, warming the in-



inches (5-10 cm)


terior of the building



thickand similarto


and contributing to



whitetopping.


the urban heat island






effect.

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Table 2: Properties that Influence Pavement Temperatures—Impacts and Applications (continued)
MAINTENANCE/REHABILITATION (continued)
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PavementType
Description of
Properties to Consider
Pavement Tempera-
Urban Climate Impacts
Issues and Consider-
Target Use

Technology

ture Impacts

ations

Reflective Pavement Options (continued)
Microsurfacing
• A thin sealing
• Solar reflectance of
+ Lowers pavement
+ Can contribute to lower
• Solar reflectance
• Used to extend pavement
with high-
layer used for road
microsurfacing will cor-
surface and sub-
air temperatures day and
may decrease over
life and on worn pave-
albedo materials
maintenance.
relate with the albedo
surface tempera-
night, although air tem-
time, if soiling from
ments that need improved

• Light-colored
of the materials used.
ture because more
peratures are not directly
traffic makes high-
friction, such as low- to

materials can be
• Researchers recently
of the sun's energy
related to surface tempera-
albedo microsurfac-
medium-volume roads.

used to increase
measured solar reflec-
is reflected away.
tures and many complicat-
ing materials darker.
airport runways, and park-

the solar reflec-
tances of microsurfac-
and there is less
ing factors are involved.
• Urban geometry.
ing areas.

tance of asphalt.
ing applications over
heat at the surface
- Reflected heat can be
particularly urban



35%.38
to absorb into the
absorbed by the sides of
canyons, influences




pavement.
surrounding buildings.
the impact high-





warming the interior of the
albedo pavements





building and contributing
have on the urban





to the urban heat island
climate.





effect.

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3. Benefits and Costs
Currently, few studies provide detailed
data on the benefits and costs of cool
pavements. This section aims to provide
a general discussion as a starting point
for decision-makers to consider and gives
examples where available. Again, decision-
makers will also consider location-specific
factors such as functionality of pavements
in the local climate, political acceptance,
and experience with the technology. Re-
sources and examples providing the latest
information are listed in Sections 4 and 5.
3.1 Benefits
Installing cool pavements can be part of
an overall strategy to reduce air tempera-
tures, which can result in a wide range of
benefits. The information below highlights
existing research in this area.
Reduced Energy Use
As noted earlier, researchers predicted that
if pavement reflectance throughout a city
were increased from 10 to 35 percent, the
air temperature could potentially be re-
duced by 1°F (0.6°C), which would result in
significant benefits in terms of lower energy
use and reduced ozone levels. For example,
an earlier, separate study estimated over $90
million/year in savings from temperature
reductions attributed to increased pavement
albedo in the Los Angeles area.39
Similarly, when permeable pavements
evaporate water and contribute to lower
air temperatures, they also provide other
energy benefits.40 Permeable pavements
can allow stormwater to infiltrate into
the ground, which decreases stormwater
runoff. With reduced runoff, communities
may realize energy savings associated with
pumping stormwater and maintaining con-
veyance structures. These cost savings may
be significant in areas where there are
Measuring Energy Savings
from Cool Roofs versus
Cool Pavements
Measuring the energy impacts from a
cool roof is relatively easy compared
with quantifying those from pave-
ment installations. With a roof, one
can measure energy demand before
and after the installation, and in a
controlled experiment, the change in
demand can be associated with the
roofing technology. In contrast, pave-
ments affect building energy demand
through influencing air temperature,
which is a more complex relation-
ship to isolate and measure.
old, combined sewers (where stormwater
drains into the sanitary sewer system).
Air Quality and Greenhouse Gas Emissions
Depending on the electric power fuel mix,
decreased energy demand associated with
cool pavements will result in lower associ-
ated air pollution and greenhouse gas emis-
sions. Cooler air temperatures also slow the
rate of ground-level ozone formation and re-
duce evaporative emissions from vehicles. A
2007 paper estimated that increasing pave-
ment albedo in cities worldwide, from an
average of 35 to 39 percent, could achieve
reductions in global carbon dioxide (C02)
emissions worth about $400 billion.41
Water Quality and Stormwater Runoff
Pavements with lower surface tempera-
tures—whether due to high solar reflec-
tance, permeability, or other factors—can
help lower the temperature of stormwater
runoff, thus ameliorating thermal shock to
aquatic life in the waterways into which
stormwater drains.42 Laboratory tests with
COOL PAVEMENTS -
DRAFT
23

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permeable pavers have shown reductions
in runoff temperatures of about 3-7°F
(2-4°C) in comparison with conventional
asphalt paving.
Permeable pavements allow water to
soak into the pavement and soil, thereby
reducing stormwater runoff, recharging
soil moisture, and improving water qual-
ity by filtering out dust, dirt, and pollut-
ants.^45 Outdoor testing and laboratory
measurements have found that permeable
pavements can reduce runoff by up to
90 percent.48 Reducing runoff decreases
scouring of streams, and, in areas with
combined sewers, this flow reduction can
help minimize combined sewer overflows
that discharge sewage and stormwater into
receiving waters. The amount of water
that these pavements collect varies based
on the type of aggregate used and the po-
rosity of the pavements, as well as on the
absorptive ability of the materials support-
ing the pavement.
Increased Pavement Life and Waste Reduction
Reducing pavement surface temperatures
can reduce the risk of premature failure of
asphalt pavements by rutting (depressions
in the wheelpaths) where the combina-
tion of slow heavy trucks or buses and hot
temperatures make this a concern. Some
full-scale testing of a typical asphalt pave-
ment showed that it took 65 times more
passes of a truck wheel to rut the pave-
ment when the temperature just below the
surface was reduced from 120°F (49 C)
to 106°F (41°C).47 In general, reducing
the surface temperatures of asphalt pave-
ments will also slow the rate of "aging"
that contributes to other distresses. For
concrete pavement, reducing daytime sur-
face temperatures in locations that experi-
ence very hot temperatures in the day and
cool temperatures at night will reduce the
temperature-related stresses that contrib-
ute to cracking.48
Figure 9: Slag Cement Airport Expansion
The Detroit Metro Airport used 720,000 square
feet (67,000 m2) of slag cement in an airport
terminai expansion project. In this region, the iocal
aggregate is susceptible to alkali-silica reaction,
whereas slag resists that form of corrosion
better than plain cement and is easier to place
in hot weather. This approach increased the iife
expectancy of the paved surfaces, as well as
allowed for the use of a high-albedo product.49
Quality of Life Benefits
Cool pavements may provide additional
benefits, such as:
•	Nighttime illumination. Reflective
pavements can enhance visibility at
night, potentially reducing lighting
requirements and saving money and
energy. European road designers often
take pavement color into account when
planning lighting.50
•	Comfort improvements. Using reflec-
tive or permeable pavements where
people congregate or children play
can provide localized comfort benefits
through lower surface and near-surface
air temperatures.51
•	Safety. Permeable roadway pavements
can enhance safety because better wa-
ter drainage reduces water spray from
moving vehicles, increases traction, and
may improve visibility by draining wa-
ter that increases glare.52
24
REDUCING URBAN HEAT ISLANDS - DRAFT

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3.2 Costs
Cool pavement costs will depend on many
factors including the following:
•	The region
•	Local climate
•	Contractor
•	Time of year
•	Accessibility of the site
•	Underlying soils
•	Project size
•	Expected traffic
•	The desired life of the pavement.
Most cost information is project specific,
and few resources exist that provide
general cost information. For permeable
pavement, however, the Federal Highway
Administration (FHWA) has noted that
Table 3: Comparative Costs of Various Pavements54
porous asphalt costs approximately 10 to
15 percent more than regular asphalt, and
porous concrete is about 25 percent more
expensive than conventional concrete.53
These comparisons pertain to the surface
layer only.
Table 3 (below) summarizes a range of
costs for conventional and cool pave-
ments, based on available sources. The
data should be read with caution, as many
project-specific factors—as highlighted
above—will influence costs. These costs
are estimates for initial construction or
performing maintenance, and do not
reflect life-cycle costs. Decision-makers
generally contact local paving associations
and contractors to obtain more detailed,
location-specific information on the costs
and viability of cool pavements in their
particular area.


Approximate
Installed Cost,
Estimated Service
Basic Pavement Types
Example Cool Approaches
$/squarefoot*
Life, Years

New Construction


Asphalt (conventional)
Hot mix asphalt with light aggregate,
if locally available
$0.10-$ 1.50
7-20
Concrete (conventional)
Portland cement, plain-jointed
$0.30-$4.50
15-35
Nonvegetated permeable pave-
Porous asphalt
$2.00-$2.50
7-10
ment
Pervious concrete
$5.00-$6.25
15-20

Paving blocks
$5.00-$ 10.00
>20
Vegetated permeable pave-
ment
Grass/gravel pavers
Maintenance
$1.50-$5.75
> 10
Surface applications
Chip seals with light aggregate, if
locally available
$0.10—$0.15
2-8

Microsurfacing
$0.35-$0.65
7-10

Ultra-thin whitetopping
$1.50-$6.50
10-15
* Some technologies, such as permeable options, may reduce the need for other infrastructure, such as stormwater
drains, thus lowering a project's overall expenses. Those savings, however, are not reflected in this table. (1 square foot
= 0.09 m2)
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3.3 Life-Cycle Cost and Environmental
Impact Considerations
The term "life cycle" refers to all the
phases of a pavement's life, from materials
production through construction,
maintenance, and use, and finishing with
the end-of-life phase where the pavement
is rehabilitated, recycled, or removed.
Two types of calculations are typically
performed for a pavement's life cycle: cost
and environmental impact.
Life-cycle cost analysis (LCCA) can help
in evaluating whether long-term benefits
can outweigh higher up-front costs. Many
agencies use LCCA to evaluate pavement
structure options. The Federal Highway
Administration has software for LCCA
called Real Cost.55-56-57
Although permeable pavement costs may
be higher than conventional, impermeable
technologies, these costs are often offset
by savings from reduced requirements for
grading, treatment ponds, or other drainage
features, such as inlets and stormwater
pipes.58 For a community, the cumulative
reductions in stormwater flows from sites
can provide significant savings in the
municipal infrastructure. If the community
has combined sewers, there could also be
environmental, social, and cost benefits
from reducing combined sewer overflows,
as well as potentially avoiding part of the
increased infrastructure costs associated
with combined sewer operation.
Life-cycle assessment (LCA) considers the
environmental impacts throughout the
life of the pavement. The International
Standard Organization has published a
generic LCA guideline for all industrial
products (the ISO 14040 series of
documents).59 The National Institute of
Standards and Technology has developed
Building for Environmental and Economic
Sustainability (BEES), a software tool that
uses the ISO 14040 series of standards
to estimate life-cycle environmental
impacts from the production and use of
asphalt, Portland cement, fly ash cement,
and other paving materials in a building
environment. The BEES software also has
an LCCA module.60 Although not directly
related to urban heat island mitigation,
this tool can help quantify some of the
environmental and cost impacts from a
variety of pavement choices.
LCA for road pavements is a nascent
field. A workshop was held in May 2010
regarding implementation of ISO 14040
for roads and issues that remain to be
resolved.61 LCA has not been used to date
to compare the environmental impacts of
permeable or reflective versus conventional
pavement. In general, until more data on
cool pavement environmental impacts and
costs exist, communities may need to think
broadly to determine if a cool pavement
application is appropriate. Sustainability
initiatives, in some areas, are motivating
communities to try cooler alternatives, as
discussed in Section 4.
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4. Cool Pavement Initiatives
The growing interest in lowering urban
temperatures and designing more sustain-
able communities has helped spur activ-
ity in the cool pavement arena. Most of
the effort has focused on research, due to
information gaps and the lack of specific
data quantifying cool pavement benefits.
More information on resources and exam-
ples are provided at the end of this sec-
tion and in Section 5. Highlights of some
cool pavement efforts are below:
•	Arizona State University's National
Center of Excellence (NCE) SMART
Innovations for Urban Climate and
Energy.62 This group is studying es-
tablished and emerging designs that
optimize albedo, emissivity, thermal
conductivity, heat storage capacity, and
density in laboratory and field sites.
NCE is developing models, particularly
for the Phoenix area but also beyond,
to help decision-makers predict the
effects of material properties, shading,
and energy use on urban temperatures.
•	The National Academies of Science's
Transportation Research Board
(TRB) Subcommittee on Paving Ma-
terials and the Urban Climate. TRB
established this Subcommittee in Janu-
ary 2008 to help advance the science of
using pavements for heat island mitiga-
tion and addressing other urban climate
concerns.
•	Trade association efforts. Represen-
tatives from the asphalt and concrete
trade associations are participating in
cool pavement efforts, such as the TRB
Subcommittee on Paving Materials and
the Urban Climate, as well supporting
research and training related to cool
pavement. For example, the National
Asphalt Pavement Association has been
investigating high-albedo asphalt pave-
ments, the National Ready Mixed Con-
crete Association is leading seminars on
pervious concrete, and the Interlocking
Concrete Pavement Institute (ICPI) is
providing professional seminars on per-
meable pavements in cooperation with
the Low Impact Development Center
and North Carolina State University.63
These research efforts are expanding op-
portunities for identifying, applying, and
studying cool pavement technologies.
Sustainability or green building initiatives
are helping to encourage cool pavement
installations.
•	Evanston, Illinois, includes permeable
pavements in its assessment of green
buildings.64
•	Chicago's Green Alley program aims
to use green construction techniques to
repave over 1,900 miles of alleys, and
offers a handbook for installing per-
meable pavements for heat reduction,
stormwater management, and other
benefits.65
•	Environmental rating programs such
as Leadership in Energy and Environ-
mental Design (LEED), Green Globes,
and EarthCraft award points to designs
that incorporate certain permeable
pavements or pavements of a certain
solar reflectance index. They also give
points for using local and recycled ma-
terials, such as slag, and reducing the
pavement used on a site.
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Growing Concern about
Synthetic Turf
Many communities have begun to
examine the health impacts from
synthetic turf surfaces, which include
the effects from high temperatures.
One researcher in New York found
that artificial sports fields could be
up to 60QF (16°C) hotter than grass,
potentially causing skin injuries to
athletes as well as contributing to the
heat island effect. These data, though
not directly related to pavements, can
help advance our understanding of
how different materials interact with
the urban climate.66
Figure 11: Grass Paving
Table 4 on page 29 summarizes other cool
pavement initiatives. Refer to the "Heat
Island Reduction Activities" chapter of this
compendium for further examples.
Although cool pavements are still in their
infancy compared with the other heat
island mitigation strategies—trees and
vegetation, green roofs, and cool roofs—
interest and momentum are growing.
Research efforts these past few years have
greatly increased, particularly in the area
of permeable pavements. As local and
state transportation and environmental
agencies work together to address energy,
sustainability, heat-health, and other
concerns, communities can expect to
see more cool pavement installations.
Activity in the private sector has also been
encouraging, as architects, developers,
and others are taking leadership roles in
advancing sustainable technologies. This
chapter, which currently provides a starting
point for communities and decision-
makers, will evolve as more information
becomes available.
This 300,000-square-foot (28,000 m2) parking lot
outside a stadium in Houston uses plastic grid
pavers that allow grass to grow in the open spaces.
28
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Alternative Paving under the Cool Houston Plan
While most communities have no, or limited, cool pavement experience, Houston's
heat island initiative recommends alternative pavements as part of the city's overall
approach to improving air quality and public health. The plan's three-tiered strategy
includes:
•	Targeting alternative paving options for specific types of paved surfaces, such as
highways or parking lots, or expanding residential or commercial roadways. This
requires coordination with the Texas Department of Transportation and the Texas
Commission on Environmental Quality.
•	Educating local and state decision-makers about public health, environmental
management, and public works maintenance benefits of alternative pavements.
•	Combining and embedding alternative paving incentives into larger programs
and regulations, such as meeting Clean Air or Clean Water Act standards, with the
support of the Greater Houston Builders Association and the Texas Aggregates
and Concrete Association.
Table 4: Examples of Cool Pavement Initiatives
Type of
Initiative
Description
Links to Examples
Research
Industry
—Since 1928, the National Ready Mixed Concrete Association's
research laboratory has helped evaluate materials and set technical standards. Recent
projects include developing permeability tests and assessing concrete with high fly-
ash content.

National
laboratory
—The Heat Island Group at Lawrence
Berkeley National Laboratory (LBNL) provides research and information about cool
paving and other heat island mitigation measures. The Cool Pavements section
describes the benefits of this technology, and published reports are included under
Recent Publications.

University-
supported
and similar
—Arizona State University's National Center
of Excellence collaborates with industry and government to research and develop
technologies to reduce urban heat islands, especially in desert climates.

consortia
—The Houston Advanced Research Center
(HARC) brings together universities, local governments, and other groups interested in
improving air quality and reducing heat islands. It has examined how cool paving could
be implemented in the Houston area to reduce urban heat island effects.


 and —North Carolina State University has an
active permeable pavement research program, as well as a specialized collaborative
effort with ICPI and the Low Impact Development Center on permeable interlocking
concrete pavements.
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Table 4: Examples of Cool Pavement Initiatives (cont.)
Type of
Initiative
Description
Links to Examples
Voluntary
efforts
Demonstration
programs
—
Poulsbo, Washington, used a $263,000 grant from the Washington Department of
Ecology to pave 2,000 feet of sidewalk with pervious pavement, making it one of the
largest pervious surface projects in the state.


—The nonprofit Heifer Interna-
tional used pervious pavement and other sustainable techniques for its new head-
quarters in Arkansas.

Outreach &
education
< www.epa.gov/heatisland/>—EPA's Heat Island Reduction Initiative provides infor-
mation on the temperature, energy, and air quality impacts from cool pavements and
other heat island mitigation strategies.


—EPA's Office of Water
highlights design options, including permeable pavements that reduce stormwater
runoff and water pollution.


—The Green Highways Partnership, supported by a number
of groups including EPA and the U.S. Department ofTransportation is a public-private
partnership dedicated to transforming the relationship between the environment and
transportation infrastructure. The partnership's Web site includes a number of cool pave-
ment resources, especially with respect to permeable pavements.


—The University of Connecticut runs Nonpoint
Education for Municipal Officials (NEMO), which helps educate local governments
about land use and environmental quality.

Tools
—The National Institute of Standards and
Technology (NIST) has developed a software tool. Building for Environmental and
Economic Stability (BEES). The tool enables communities to conduct life cycle cost
assessments for various types of building initiatives, including pavement projects.
Policy
efforts
Municipal
regulations that
support cool
—The Cool Hous-
ton! Plan promotes cool paving as well as other techniques to reduce the region's
heat island.

pavements
—
Toronto's"Design Guidelines for'Greening'Surface Parking Lots"encourage reflective
and permeable pavements to reduce surface temperatures.
30
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5. Resources
The organizations below may provide additional information on alternative, or cool,
pavement technologies.
Program/Organization
Role
Web Address
The Federal Highway
Administration's (FHWA)
Office of Pavement
Technology
The Office of PavementTechnology conducts research
and training related to asphalt and concrete pavements.

FHWA's Office of Planning,
Environment,and Realty
This office's Web site provides information regarding
transportation planning and the environment.
< www.f h wa .d ot.g o v/h e p/
index.htm>
American Association
of State Highway and
Transportation Officials
Center for Environmental
Excellence (AASHTO)
AASHTO created the Center for Environmental Excellence
in cooperation with the Federal Highway Administration
to offer technical assistance about environmental
regulations and ways to meet them.

Association of Metropolitan
Planning Organizations
(AMPO)
AMPO supports local MPOs through training,
conferences, and assistance with policy development.

The American Concrete
Pavement Association (ACPA)
ACPA promotes concrete pavement by working with
industry and government.

The Asphalt Pavement
Alliance (APA)
A consortium of the National Asphalt Paving Association
(NAPA), the Asphalt Institute (Al),and state paving
associations, APA promotes hot mix asphalt through
research, development, and outreach. Individual state
asphalt associations are a good source for local paving
considerations.

Interlocking Concrete
Pavement Institute (ICPI)
ICPI has a document that compares permeable pavement
technologies and helps readers find certified installers.

National Center for Asphalt
Technology (NCAT)
NCAT provides up-to-date strategies for designing and
constructing asphalt pavements.

National Ready Mixed
Concrete Association
Since 1928, the National Ready Mixed Concrete
Association's research laboratory has helped evaluate
materials and set technical standards. Recent projects
include developing permeability tests and assessing
concrete with high fly-ash content.

Portland Cement Association
(PCA)
PCA represents cement companies in the United States
and Canada and conducts research, development, and
outreach.

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Endnotes
1	Statistics are from urban fabric analyses conducted by Lawrence Berkeley National Laboratory
Rose, L.S., H. Akbari, and H. Taha. 2003. Characterizing the Fabric of the Urban Environment: A
Case Study of Greater Houston, Texas. Paper LBNL-51448. Lawrence Berkeley National Labora-
tory, Berkeley, CA.
Akbari, H. and L.S. Rose. 2001. Characterizing the Fabric of the Urban Environment: A Case
Study of Metropolitan Chicago, Illinois. Paper LBNL-49275. Lawrence Berkeley National Labora-
tory, Berkeley, CA. Akbari, H. and L.S. Rose. 2001. Characterizing the Fabric of the Urban Envi-
ronment: A Case Study of Salt Lake City, Utah. Paper LBNL-47851. Lawrence Berkeley National
Laboratory, Berkeley, CA. Akbari, H., L.S. Rose, and H. Taha. 1999. Characterizing the Fabric of
the Urban Environment: A Case Study of Sacramento, California. Paper LBNL-44688. Lawrence
Berkeley National Laboratory, Berkeley, CA.
2	Pomerantz, M., B. Pon, H. Akbari, and S.-C. Chang. 2000. The Effect of Pavements' Temperatures
on Air Temperatures in Large Cities. Paper LBNL-43442. Lawrence Berkeley National Laboratory,
Berkeley, CA. See also Cambridge Systematics. 2005. Cool Pavement Draft Report. Prepared for
U.S. EPA.
3	See, generally, U.S. EPA 2008. Green Parking Lot Resource Guide. EPA 510-B-08-001.
4	Golden, J.S., J. Carlson, K. Kaloush, and P. Phelan. 2006. A Comparative Study of the Thermal
and Radiative Impacts of Photovoltaic Canopies on Pavement Surface Temperatures. Solar
Energy. 81(7): 872-883. July 2007.
5	Kinouchi, T., T. Yoshinaka, N. Fukae, and M. Kanda. 2004. Development of Cool Pavement
with Dark Colored High Albedo Coating. Paper for 5th Conference for the Urban Environment.
Vancouver, Canada. Retrieved November 15, 2007, from .
6	National Center of Excellence on SMART Innovations at Arizona State University. 2007. What Fac-
tors Influence Elevated Pavement Temperatures Most During Day and Night? Case Study 1(1).
7	The Portland Cement Association thoroughly explains concrete cement at , and state and federal government sites, among others, define as-
phalt. Two useful ones are  and
.
8	Levinson, R. and H. Akbari. 2001. Effects of Composition and Exposure on the Solar Reflec-
tance of Portland Cement Concrete. Paper LBNL-48334. Lawrence Berkeley National Laboratory,
Berkeley, CA.
9	National Center of Excellence on SMART Innovations at Arizona State University. 2007. What
Factors Influence Elevated Pavement Temperatures Most During Day and Night? Case Study
1(1).
10	Levinson, R., H. Akbari, S. Konopacki, and S. Bretz. 2002. Inclusion of Cool Roofs in Nonresi-
dential Title 24 Prescriptive Requirements. Paper LBNL-50451. Lawrence Berkeley National
Laboratory, Berkeley, CA.
11	See:
Haselbach, L. 2008. Pervious Concrete and Mitigation of the Urban Heat Island Effect. Un-
der review for the 2009 Transportation Research Board Annual Meeting.
Kevern, J., V.R. Schaefer, and K. Wong. 2008. Temperature Behavior of a Pervious Concrete
System. Under review for the 2009 Transportation Research Board Annual Meeting.
32
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12	For a general overview of permeable pavements, see Ferguson, B. 2005. Porous Pavements.
13	See, generally:
Haselbach, L. 2008. Pervious Concrete and Mitigation of the Urban Heat Island Effect. Un-
der review for the 2009 Transportation Research Board Annual Meeting.
Kevern, J., V.R. Schaefer, and K. Wong. 2008. Temperature Behavior of a Pervious Concrete
System. Under review for the 2009 Transportation Research Board Annual Meeting.
14	There are a number of resources available on Japan's efforts with water retentive pave-
ments, although there is no centralized source that compiles these initiatives. For examples
of the research and published summaries available, see the following (all Web sites accessed
September 17, 2008):
Karasawa, A., K. Toriiminami, N. Ezumi, K. Kamaya. 2006. Evaluation Of Performance Of
Water-Retentive Concrete Block Pavements. 8th International Conference on Concrete Block
Paving, November 6-8, 2006, San Francisco, California.
Ishizuka, R., E. Fujiwara, H. Akagawa. 2006. Study On Applicability Of Water-Feed-Type
Wet Block Pavement To Roadways. 8th International Conference on Concrete Block Paving,
November 6-8, 2006, San Francisco, California.
Yamamoto, Y. 2006. Measures to Mitigate Urban Heat Islands. Quarterly Review No. 18.
January 2006. Available online at .
Yoshioka, M., H. Tosaka, K. Nakagawa 2007. Experimental and Numerical Studies of the
Effects of Water Sprinkling on Urban Pavement on Heat Island Mitigation. American Geo-
physical Union, Fall Meeting 2007, abstract #1H3D-1607.
Yamagata H., M. Nasu, M. Yoshizawa, A. Miyamoto, and M. Minamiyama. 2008. Heat island
mitigation using water retentive pavement sprinkled with reclaimed wastewater. Water
science and technology. 57(5): 763-771. Abstract available online at .
15	Christen, A. and R. Vogt. 2004. Energy and radiation balance of a Central European city. Interna-
tional Journal of Climatology. 24(ii):1395-l421.
16	Golden, J.S. and K. Kaloush. 2006. Meso-Scale and Micro-Scale Evaluations of Surface Pavement
Impacts to the Urban Heat Island Effects. The International Journal of Pavement Engineering.
7(1): 37-52. March 2006.
17	Pomerantz, M., B. Pon, H. Akbari, and S.-C. Chang. 2000. The Effect of Pavements' Temperatures
on Air Temperatures in Large Cities. Paper LBNL-43442. Lawrence Berkeley National Laboratory,
Berkeley, CA.
18	Taha, H. 1997. Modeling the impacts of large-scale albedo changes on ozone air quality in the
South Coast Air Basin. Atmospheric Environment. 31(11): 1667-1676.
Taha, H. 1996. Modeling the Impacts of Increased Urban Vegetation on the Ozone Air Quality in
the South Coast Air Basin. Atmospheric Environment. 30(20): 3423-3430.
19	Rosenfeld, A.H., J.J. Romm, H. Akbari, and M. Pomerantz. 1998. Cool Communities: Strategies
for Heat Islands Mitigation and Smog Reduction. Energy and Buildings. 28:51-62.
20	Tran, N., B. Powell, H. Marks, R. West, and A. Kvasnak. 2008. Strategies for Design and Con-
struction of High-Reflectance Asphalt Pavements. Under review for the 2009 Transportation
Research Board Annual Meeting.
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Statistics are from urban fabric analyses conducted by Lawrence Berkeley National Laboratory
Rose, L.S., H. Akbari, and H. Taha. 2003. Characterizing the Fabric of the Urban Environment: A
Case Study of Greater Houston, Texas. Paper LBNL-51448. Lawrence Berkeley National Labora-
tory, Berkeley, CA.
Akbari, H. and L.S. Rose. 2001. Characterizing the Fabric of the Urban Environment: A Case
Study of Metropolitan Chicago, Illinois. Paper LBNL-49275. Lawrence Berkeley National Labora-
tory, Berkeley, CA. Akbari, H. and L.S. Rose. 2001. Characterizing the Fabric of the Urban Envi-
ronment: A Case Study of Salt Lake City, Utah. Paper LBNL-47851. Lawrence Berkeley National
Laboratory, Berkeley, CA. Akbari, H., L.S. Rose, and H. Taha. 1999. Characterizing the Fabric of
the Urban Environment: A Case Study of Sacramento, California. Paper LBNL-44688. Lawrence
Berkeley National Laboratory, Berkeley, CA.
See, e.g., Mallick, R.B., P.S. Kandhal, L.A. Cooley, Jr., and P.E. Watson. 2000. Design, Construc-
tion, and Performance of New-generation Open-graded Friction Courses. Paper prepared for
annual meeting of Association of Asphalt Paving Technologists, Reno, NV, March 13-15, 2000.
Tran, N., B. Powell, H. Marks, R. West, and A. Kvasnak. 2008. Strategies for Design and Con-
struction of High-Reflectance Asphalt Pavements. Under review for the 2009 Transportation
Research Board Annual Meeting.
More information on fly ash is available through EPA's Coal Combustion Products Partnership,
.
Boriboonsomsin, K. and F. Reza. 2007. Mix Design and Benefit Evaluation of High Solar Reflec-
tance Concrete for Pavements. Paper for 86th Annual Meeting of the Transportation Research
Board. Washington, D.C.
Office of the Governor. 2006. Statement by Gov. Schwarzenegger on U.S. EPA Award for Cali-
fornia's Leadership in the Construction Use of Waste Products. Retrieved July 15, 2008, from

Pomerantz, M., B. Pon, H. Akbari, and S.-C. Chang. 2000. The Effect of Pavements' Temperatures
On Air Temperatures in Large Cities. Paper LBNL-43442. Lawrence Berkeley National Labora-
tory, Berkeley, CA. See also Tran, N., B. Powell, H. Marks, R. West, and A. Kvasnak. 2008. Strate-
gies for Design and Construction of High-Reflectance Asphalt Pavements. Under review for the
2009 Transportation Research Board Annual Meeting.
Aseda, T., V.T. Ca, and A. Wake. 1993. Heat Storage of Pavement and its Effect on the Lower
Atmosphere. Atmospheric Environment. 30(3): 413-427. 1996.
Tran, N., B. Powell, H. Marks, R. West, and A. Kvasnak. 2008. Strategies for Design and Con-
struction of High-Reflectance Asphalt Pavements. Under review for the 2009 Transportation
Research Board Annual Meeting.
Levinson, R. and H. Akbari. 2001. Effects of Composition and Exposure on the Solar Reflec-
tance of Portland Cement Concrete. Paper LBNL-48334. Lawrence Berkeley National Laboratory,
Berkeley, CA.
Tran, N., B. Powell, H. Marks, R. West, and A. Kvasnak. 2008. Strategies for Design and Con-
struction of High-Reflectance Asphalt Pavements. Under review for the 2009 Transportation
Research Board Annual Meeting.
National Center of Excellence on SMART Innovations at Arizona State University. 2007.
Alternative Paving—Recycling Crumb Rubber. Case Study, 1(3).
Haselbach, L. 2008. Pervious Concrete and Mitigation of the Urban Heat Island Effect. Under
review for the 2009 Transportation Research Board Annual Meeting.
34
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34
35
36
37
38
39
40
41
42
44
45
46
47
48
Haselbach, L. 2008. Pervious Concrete and Mitigation of the Urban Heat Island Effect. Under
review for the 2009 Transportation Research Board Annual Meeting.
Yamagata H., M. Nasu, M. Yoshizawa, A. Miyamoto, and M. Minamiyama. 2008. Heat island miti-
gation using water retentive pavement sprinkled with reclaimed wastewater. Water science and
technology. 57(5): 763-771. Abstract available online at .
Yamagata H., M. Nasu, M. Yoshizawa, A. Miyamoto, and M. Minamiyama. 2008. Heat island miti-
gation using water retentive pavement sprinkled with reclaimed wastewater. Water science and
technology. 57(5): 763-771. Abstract available online at .
Pomerantz, M., H. Akbari, S.-C. Chang, R. Levinson and B. Pon. 2003. Examples of Cooler Reflec-
tive Streets for Urban Heat-Island Mitigation: Portland Cement Concrete and Chip Seals. Paper
LBNL-49283. Lawrence Berkeley National Laboratory, Berkeley, CA.
Tran, N., B. Powell, H. Marks, R. West, and A. Kvasnak. 2008. Strategies for Design and Con-
struction of High-Reflectance Asphalt Pavements. Under review for the 2009 Transportation
Research Board Annual Meeting.
Rosenfeld, A.H., J.J. Romm, H. Akbari, and M. Pomerantz. 1998. "Cool Communities: Strategies
for Heat Islands Mitigation and Smog Reduction," Energy and Buildings, 28, pp. 51-62.
Pomerantz, M., B. Pon, H. Akbari, and S.-C. Chang. 2000. The Effect of Pavements' Temperatures
on Air Temperatures in Large Cities. Paper LBNL-43442. Lawrence Berkeley National Laboratory,
Berkeley, CA.
Akbari, H., and S. Menon. 2007. Global Cooling: Effect of Urban Albedo on Global Temperature.
Paper for the Proceedings of the International Seminar on Planetary Emergencies. Erice, Sicily.
U.S. EPA. 2003. Beating the Heat: Mitigating Thermal Impacts. Nonpoint Source News-Notes.
72:23-26.
43 James, W. 2002. Green Roads: Research into Permeable Pavers. Stormwater. Retrieved
May 8, 2008 from .
U.S. EPA. Reducing Stormwater Costs through Low Impact Development (LID) Strategies and
Practices. EPA 841-F-07-006, December 2007. Retrieved April 2, 2008 from .
Booth, D. and J. Leavit. 1999. Field Evaluation of Permeable Pavement Systems for Improved
Stormwater Management. Journal of the American Planning Association. 65(3): 314-325.
James, W. 2002. Green Roads: Research into Permeable Pavers. Stormwater. Retrieved
May 8, 2008 from .
Pomerantz, M., H. Akbari, and J. Harvey. 2000. Durability and Visibility Benefits of Cooler Re-
flective Pavements. Paper LBNL-43443. Lawrence Berkeley National Laboratory, Berkeley, CA.
ARA Inc., ERES Consultants. 2004. Guide for Mechanistic-Empirical Design of New and Reha-
bilitated Pavement Structures, Part 3. Design Analyis, Ch. 4 Design of New and Reconstructed
Rigid Pavements. Final Report Project 1-37A. National Cooperative Highway Research Program,
Transportation Research Board, National Academy of Science. Washington DC.
19 Bijen, Jan. 1996. Benefits of slag and fly ash. Construction and Building Materials 10.5: 309-314.
See also the Federal Highway Administration's summary of slag cement at .
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50	U.S. Department of Transportation, Federal Highway Administration. European Road Lighting
Technologies. International Technology Exchange Program: September 2001. Retrieved June 16,
2008, from . See also: Interna-
tional Commission on Illumination. 2007. Road Transport Lighting for Developing Countries.
CIE 180:2007.
51	Kinouchi, T., T. Yoshinaka, N. Fukae, and M. Kanda. 2004. Development of Cool Pavement
with Dark Colored High Albedo Coating. Paper for 5th Conference for the Urban Environment.
Vancouver, Canada. Retrieved November 15, 2007, from .
52	U.S. Department of Transportation, Federal Highway Transportation Administration. 2005. Tech-
nical Advisory: Surface Texture for Asphalt and Concrete Pavements. Retrieved September 17,
2008, from . Michigan Depart-
ment of Environmental Quality. 1992. Porous Asphalt Pavement. Retrieved 16 Sep 2008 from
.
53	U.S. Department of Transportation, Federal Highway Administration. Stormwater Best Manage-
ment Practices in an Ultra-Urban Setting: Selection and Monitoring. Fact Sheet - Porous Pave-
ments. Retrieved April 2, 2008, from .
54	Figures are taken from multiples sources and express the maximum range of the values: 1)
Cambridge Systematics. 2005. Cool Pavement Draft Report. Prepared for U.S. EPA. 2) ASU's draft
of the Phoenix Energy and Climate Guidebook. 3) Center for Watershed Protection. 2007. Rede-
velopment Projects. New York State Stormwater Management Design Manual. Prepared for New
York State Department of Environmental Conservation. Retrieved June 13, 2008, from . 4) Bean, E.Z.,W.F. Hunt, D.A. Bidelspach, and
J.T. Smith. 2004. Study on the Surface Infiltration Rate of Permeable Pavements. Prepared for
Interlocking Concrete Pavement Institute. 5) Interlocking Concrete Pavement Institute. 2008.
Permeable Interlocking Concrete Pavements: A Comparison Guide to Porous Asphalt and Pervi-
ous Concrete. 6) Pratt, C.J. 2004. Sustainable Drainage: A Review of Published Material on the
Performance of Various SUDS Components. Prepared for The Environment Agency. Retrieved
June 13, 2008, from . 7) NDS, Inc. Technical
Specifications for Grass Pavers. Retrieved June 13, 2008, from . 8) Tran, N., B. Powell, H. Marks, R. West, and A. Kvasnak.
2008. Strategies for Design and Construction of High-Reflectance Asphalt Pavements. Under
review for the 2009 Transportation Research Board Annual Meeting.
55	Federal Highway Administration. 2002. Life Cycle Cost Analysis Primer. FHWA-IF-02-047. Of-
fice of Asset Management. Washington DC. August. 25 pp. Accessible at http://www.fhwa.dot.
gov/infrastructure/asstmgmt/lccasoft.cfm.
56	D. Walls, J., M. Smith. 1998. Life-Cycle Cost Analysis in Pavement Design —Interim Technical
Bulletin. FHWA-SA-98-079. Federal Highway Administration. September. 107pp . Accessible at
http ://isddc. dot. gov/ OLPF iles/FHWA/ 013017. pdf.
57	Federal Highway Administration. Real Cost, version 2.5. Accessible at http://www.fhwa.dot.
gov/infrastructure/asstmgmt/lccasoft.cfm.
58	U.S. EPA. 2007. Reducing Stormwater Costs through Low Impact Development (LID) Strategies
and Practices. EPA 841-F-07-006. Retrieved April 2, 2008, from .
59	International Standards Organization. Documents can be purchased at http://www.iso.org/iso/
catalogue_detail?csnumber=37456.
36
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60	See the Building for Environmental and Economic Sustainability (BEES) software at
.
61	Information on the LCA for Pavements Workshop held in May, 2010 is available at www.ucprc.
ucdavis. edu/ p-lca.
62	National Center of Excellence on SMART Innovations at Arizona State University
.
63	The National Asphalt Pavement Association conducts training and professional development
(see ) and the National Ready Mixed Concrete Association has a research
lab near College Park, Maryland, and conducts training and professional development (see
 for details). For the Interlocking Concrete Pavement Institute seminars, see
. See also recent sponsored research efforts, such as:
Kevern, J., V.R. Schaefer, and K. Wong. 2008. Temperature Behavior of a Pervious Concrete
System. Under review for the 2009 Transportation Research Board Annual Meeting.
Tran, N., B. Powell, H. Marks, R. West, and A. Kvasnak. 2008. Strategies for Design and Con-
struction of High-Reflectance Asphalt Pavements. Under review for the 2009 Transportation
Research Board Annual Meeting.
64	For the design guidelines, see .
65	City of Chicago. Chicago Green Alley Handbook. Retrieved May 15, 2008, from .
66	See.
Claudio, L. 2008. Synthetic Turf: Health Debate Takes Root. Environmental Health Perspec-
tives 116.3. Retrieved September 16, 2008, from .
Aubrey, A. 2008. High Temps On Turf Fields Spark Safety Concerns. NPR Morning Edi-
tion, 7 Aug. Retrieved September 16, 2008, from .
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