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An Updated Holistic Look at Old Assumptions: Insights from Three New Studies on Roof Albedo

January 8, 2025

Cool Roof

THE GROWING AWARENESS of climate
change, as well as the related issues of urban
heat islands and steadily increasing energy
costs, has led to a growing interest in the
effectiveness of reflective, or “cool” roofs (i.e.,
roofs that are designed to reflect more sunlight
and therefore
absorb less solar energy than a
conventional roof). Proponents of reflective
roofs have recommended their use throughout
the US to save energy and mitigate the effects
of urban heat islands (UHIs), and some cities
have moved toward mandating the use of white
roofs on all new construction, roofing removal,
and replacement as well.
Because EPDM Roofing Association (ERA)
members make a variety of roofing membranes
of various colors and roofing products used in
countless
geographic locations and building
types, ERA’s members believe it is incumbent on
policymakers to verify the purported advantages
of cool roofs and ensure that building owners
and designers are free to decide how best to
use EPDM roofing products to meet their roof
performance and sustainability goals. ERA
members contend that two fundamental questions
should be answered before additional
mandates are enacted. First, do reflective or
cool-roof mandates
in a given locality have
the desired impact of reducing or limiting
the
development of UHIs? And second, to what
extent is there sufficient certainty in the protocol
by which UHI is quantified to determine this at
all? Does roof albedo or insulation matter more
in achieving improved energy efficiency?
Recently, ERA turned to researchers
in Clemson University’s Department of
Construction Science and Management and
ICF, one of the nation’s foremost energy and
environment consulting firms, to answer these
questions. This research, which was conducted
from 2019 to 2023, includes a critical review of
the relevant literature by the Clemson University
researchers titled “The Impact of Membrane
An Updated Holistic Look
at Old Assumptions:
Insights from Three New
Studies on Roof Albedo
Feature
By Ellen Thorp, MA, CAE; and Jason Wilen,
RRO, AIA, CDT
Color and Roof Albedo on Energy Efficiency and
Urban Heat Islands,”1 and two original studies
by ICF: “Assessing the Effects of Local Cool
Roof Policies on Urban Heat Islands”2 and “A
Comparison of Code-Compliant Roof Insulation
and Roof Albedo Impacts and Benefits on Energy
Efficiency.”3
Based on the results of these studies, the
ERA recommends that policymakers pause the
implementation
of policies that require reflective
roofing mandates and calls upon government
agencies, nongovernmental organizations,
and other stakeholders to conduct additional
research to assess the relative value of every
tactic that could be used to diminish the impact
of UHIs and increase building
energy efficiency.4
As the research suggests, many questions
need to be answered before the real-world
implications of one-size-fits-all reflective roofing
mandates can be understood and evaluated. This
article aims to begin that process by presenting
the current research on the presence of cool roofs
as tools to mitigate UHIs and enhance the energy
efficiency of buildings, identifying
areas for
improving cool-roof research, and predicting the
policy implications of enacting one-size-fits-all
roofing mandates.
©2025 International Institute of Building Enclosure Consultants (IIBEC)
Interface articles may cite trade, brand,
or product names to specify or describe
adequately materials, experimental
procedures, and/or equipment. In no
case does such identification imply
recommendation or endorsement by
the International Institute of Building
Enclosure Consultants (IIBEC).
This paper was presented at the 2024 IIBEC
International Convention and Trade Show.
22 • IIBEC Interface January 2025
LITERATURE REVIEW: THE
IMPACT OF MEMBRANE
COLOR AND ROOF ALBEDO
ON ENERGY EFFICIENCY AND
URBAN HEAT ISLANDS
The ERA contracted with researchers
in Clemson
University’s Department of Construction
Science and Management to conduct a critical
review of the published data and literature
about the impact of membrane color on energy
efficiency and UHIs, synthesize the findings
from that literature, and identify gaps in the
existing research. After examining more than
2,856 references, 178 articles and papers, and
102 original research studies, the researchers
identified questions about the use and benefits
of cool roofs that require additional and deeper
study.5
Overview of Research on the
Impact of Cool Roofs on UHI and
Energy Efficiency
According to the researchers, studies examining
the impact of cool roofs on UHIs presented
mixed results, as there are a range of factors,
including landscape, density, geographic
location and climate, and more, that contribute
to the severity of UHIs. For example, many
of the studies the researchers reviewed were
dated (that is, published at least a decade ago)
and therefore failed to consider factors relevant
to UHIs, such as the impact of high vehicular
emissions on temperatures
in areas with high
density, the effect of hardscape asphalt surfaces
compared to roofs, and the influence
of building
height. Further, the researchers reported
instances in which more recent studies based
their conclusions on these earlier studies, which
now must be considered
dated or offering
incomplete information.6
The researchers observed that conclusions
about the effect of membrane color on energy
efficiency would benefit from additional and
more timely research to support or refute
currently held perceptions, such as the notions
that increased levels of reflectivity
increase the
amount of annual energy savings, and that roof
insulation is critical in all climates. New research,
they suggest, should compare the impact of
roof albedo on energy efficiency for real-world
versus simulation-based studies, for these
simulation-based studies did not account for
aging, soiling, and weatherability of the “cool”
material during a building’s life span.6
Research Gaps and their Impact on
Implementation
Although there is an abundance of current
research that examines the impact of cool roofs
on building performance, energy efficiency, and
UHIs, there are gaps and inconsistencies in their
research methodologies that limit the application
of their findings in real-world settings. The
effectiveness of cool roofs in addressing these
issues very much depends on a combination
of factors that are unique to each city and/or
geographic location, and thus incongruous with
one-size-fits-all roof mandates.6

COMPARATIVE ANALYSIS
OF THE EFFECT OF LOCAL
COOL ROOF POLICIES ON
URBAN HEAT ISLANDS

 

To better understand the measurable
impacts
of commercial roofing surfaces on urban heat
islands (UHIs), ERA contracted with ICF, one of
the nation’s foremost energy and environment
consulting firms, to undertake a three-phase
study designed to assess whether cool-roof
mandates help mitigate UHIs (phase 1),
determine whether the proliferation of cool
roofs in a particular city positively impacts the
UHI effect with improved analytical
rigor (phase
2), and compare the strength and significance
of daytime and nighttime UHIs to determine
whether increases in cool roofs within help
mitigate UHIs within particular cities (phase 3).
The following is a summary of the methodologies
used to conduct this three-part study and its
conclusions.7
Phase I: Analysis of Select Cities
with Reflective-Roof Mandates
In phase 1, ICF researchers analyzed ambient
temperatures in three urban areas that have
had cool-roof mandates in place, compared
those temperatures to temperatures in three
similar localities that have not imposed such
mandates, and analyzed corresponding changes
in urban land surface color in those localities
to estimate the effect of commercial roof solar
reflectance on UHIs. Experimental and control
city pairs were selected to enable the comparison
of impacts between cities with and without
cool-roof mandates. Selection considered year
of cool-roof mandate implementation
and
mandate coverage; availability and resolution of
air temperature and GIS (geographic information
system) data, both before and after mandate
implementation;
and climate conditions,
including a city’s international climate zone and
microclimate, to moderate impacts confounding
weather effects. The selected experimental
(or mandate) cities and control city pairs were
New York City, NY (mandate city) and Newark,
NJ; Chicago, IL (mandate city) and Indianapolis,
IN; and Washington, DC (mandate city) and
Baltimore, MD.8
Phase 1 Results
Comparison of the cities with and without
mandates revealed no discernible correlation
between the imposition of cool-roof mandates
and UHIs. As the ICF researchers state:
• None of the three city pairs exhibited a relative
reduction in daytime UHI intensity after
the experimental city imposed a cool-roof
mandate.
• Only one of three city pairs exhibited a relative
reduction in nighttime UHI intensity after
the experimental city imposed a cool-roof
mandate.
• Three out of 12 cases (daytime and nighttime
UHI intensity for each of the six cities) showed
a negative trend between UHI intensity and
relative change in cool roof, indicating
an
uncertain, or at best, a low and localized
impact on UHIs from the imposition of
cool-roof mandates.8
Phase 2: Analysis of Cities with
High UHI and Reflective Roofing
Mandates
The aims of phase 2 were similar to those of
phase 1: assess the relative impact of commercial
cool roofs on UHIs. However, the second
analysis was designed to improve analytical
rigor; specifically, ICF proposed the use of
higher-resolution imagery to enable more
rigorous analysis of the areas of interest and yield
results more meaningful to stakeholders.9
To accomplish these objectives, two cities,
Chicago, IL, and Portland, OR, were selected for
analysis because their high amounts of white
roofing and UHIs made them good candidates
for evaluating whether there are perceptible
effects from the installation of commercial
cool
roofs on local UHIs. In addition, ICF’s preliminary
analysis of NOAA weather station and GIS data
indicated that both cities have good availability
of local weather stations with complete data and
high-resolution GIS data complete with building
layers for commercially zoned areas of interest.9
Phase 2 Study Results and
Conclusions
Air temperature analyses conducted
for
Chicago and Portland for daytime UHIs were
deemed inconclusive because they resulted
in considerably lower estimates of UHIs than
January 2025 IIBEC Interface • 23
presented in the commonly cited climate
science publication (CCCSP), and the scenarios
analyzed exhibited variable trends
with uncertainty. However, the researchers
decided that their findings may be reasonable
and accurate even if they contradict findings
in the CCCSP from which the methodology to
measure UHIs was taken.9
According to EPA, UHIs are often strongest
at nighttime because the built environment
cools and releases heat to the atmosphere
much slower than the surrounding
rural areas,
and daytime UHI can even be negative as the
rural landscape heats up faster than the urban
environment. Similar impacts were noted in
the ICF analysis, where the daytime day-to-day
UHIs were highly variable with as many days
exhibiting positive as negative UHIs.9
Because there is no standardized method
for determining UHIs, the researchers found
UHIs to be contextual and based on the needs
and objectives of those performing the study.
Therefore, while different teams of researchers
used multiple definitions and methods to
quantify UHI, the ICF researchers believed it
was reasonable to conclude that Chicago’s and
Portland’s daytime UHIs (as determined through
air-temperature analysis) were less pronounced
than indicated in the CCCSP, even though they
followed its methodology.9
Phase 3: Comparative Analysis of
Daytime and Nighttime UHI
In Phase 3 of the research, 13 cities—
Albuquerque, NM; Baltimore, MD; Buffalo, NY;
Columbus, OH; Denver, CO; Kansas City, MO;
Las Vegas, NV; Louisville, KY; Minneapolis,
MN; Philadelphia, PA; Portland, OR; San
Diego, CA; and Washington, DC—underwent a
temperature-based UHI analysis that evaluated
daytime and nighttime
changes in UHIs on
an annual basis over a period of more than a
decade. The researchers mirrored the CCCSP’s
methods by looking at the strength and
significance of daytime and nighttime UHIs
and assessing the probability of a UHI being as
prominent through the use of alternate weather
stations and summertime periods.10
Because confidence in estimating UHI is
central to the objectives of this study, the
researchers found the following notable:10
• Daytime UHI was found to be less pronounced
and more variable when compared to
nighttime UHIs, which tend to be significant
and positive.
• Due to the absence of a standardized
approach for assessing UHI, its determination
is contextual and depends on the specific
requirements and goals of the researchers.
• Daytime UHI was not strong when compared
to results from the CCCSP, and results vary
greatly according to weather station selection.
• On a day-to-day basis, daytime UHI was highly
variable, with instances where consecutive
days flipped between positive and negative
UHI.
• Air temperatures recorded at weather stations
are influenced primarily by local conditions
and rarely factor in surrounding areas.
• Daytime UHI also varied according
to the
quantity of weather stations and selected time
period.
Overall Conclusions of the Impact
of Cool-Roof Mandates on Urban
Heat Islands
Given the results of the three-phase study, an
increased presence of cool, white, or reflective
roofs, whether by mandates or market occurrence,
does not mitigate the effects of UHIs. As
noted previously,
as there is no established
method for determining or analyzing
Urban Heat
Islands (UHIs), prior research on UHIs has been
identified as context-dependent, shaped by the
unique needs and objectives of the researchers
conducting each individual study. As such, the
ICF researchers noted that there is a great need
among the scientific community to establish
standardized and reproducible methods for
defining
and measuring UHIs that will yield
reasonably consistent results.11
The researchers note that several themes
remained consistent throughout all three
phases:12
• There are many factors that impact UHI, only
one of which is commercial rooftops.
• Daytime UHI was more variable
and less
pronounced than nighttime UHI.
• There is a need for stronger and higher-quality
daytime UHI calculations.
• Air temperatures only reflect conditions near
weather stations and not broader areas.
• Analysis of daytime UHI shows inconsistent
results and is influenced
by many factors.
• The impact of cool-roof mandates on UHI is
inconclusive
and requires more research.
A COMPARISON OF
CODE-COMPLIANT ROOF
INSULATION AND ROOF
ALBEDO IMPACTS AND
BENEFITS
Cool roofs have become one of several accepted
strategies for mitigating the impacts of urban
heat islands and have long been a prescriptive
requirement of American Society of Heating,
Refrigerating and Air-Conditioning Engineers
(ASHRAE) Standard 90.1–2022, Energy Standard
for Buildings Except Low-Rise Residential
Buildings13 and the International Energy
Conservation Code (IECC)14 in Climate Zones 1,
2, and 3. These requirements generally mandate
a white or high-albedo roofing surface material
that reflects a portion of the incoming solar
radiation away from a building’s roof, before it is
transmitted to and absorbed by the building.
Cool roofs are currently not required by ASHRAE
90.1–2019 nor the IECC in Climate Zone 4 and
zones to the north, as the reduction in solar heat
gain from cool roofs tends to increase the overall
building energy use in cooler to cold climates.
To better understand and communicate
where
insulation and cool roofs provide the greatest
benefits, ERA commissioned ICF to conduct a study
designed to assess and quantify the life-cycle
energy, economics,
and emission benefits of
code-compliant roof replacements and cool-roof
projects for a select number of commercial
building types constructed with low-sloped
roofs and representative city/climate zone
24 • IIBEC Interface January 2025
combinations. The following is a summary of how
this study was conducted and its conclusions.15
To determine where insulation and cool roofs
provide the greatest benefits, ICF developed a
three-step approach designed to accomplish the
following:16
• Develop building energy models to represent
the baseline and intervention scenarios. Both
sets of models were simulated to produce
annual estimates of whole-building energy
use and their energy use was subtracted
to
produce incremental energy savings.
• Calculate energy cost savings as the
product of energy savings by fuel type and
the corresponding price of fuel and then
combined with secondary research on
incremental material and labor capital costs to
produce life-cycle economic metrics.
• Develop emissions benefits from energy
savings as the product of energy savings by fuel
type and the corresponding emissions factors.
ICF created baseline building energy models
(developed from the Department of Energy’s
commercial
prototypical building models) for the
Medium Office, Hospital, Primary School, and
Warehouse building types, in three primary and
seven sub-US climate zones. These selections
represent nine US cities and use the 2004
building energy model.15
Next, ICF developed intervention models
from the baseline building
energy models
representing the three-year solar reflectance and
thermal emittance values commonly used in
modeling for building-level code compliance.16
Intervention (I1): The black roof with codecompliant
levels of insulation intervention is
identical
to the baseline condition but with roof
insulation levels based on the ASHRAE Standard
90.1–2019 minimum rated R-value building
enclosure criteria given in the prescriptive
building envelope compliance
path for
conditioned nonresidential opaque roof (exterior)
elements for insulation
entirely above deck.
Intervention (I2): The cool roof with
baseline levels of insulation intervention
is identical to the baseline condition
but with
three-year-aged solar reflectance and thermal
emittance values of the ASHRAE 90.1–2019
standard for cool (or white) roofs.
Intervention (I3): The cool roof with codecompliant
levels of insulation intervention is
identical to the black roof with code-compliant
levels of insulation but with the three-year-aged
solar reflectance and thermal emittance of the
cool-roof intervention (I2).
With their intervention models in place, the
researchers then performed
energy use and
economic benefit (i.e., energy-cost savings,
incremental material and labor costs) analyses on
each of the intervention scenarios to determine
which offered the greatest energy savings and
economic benefit.16
The results of these analyses were mixed, as
the benefits offered by the three interventions
were determined by the characteristics
of the
four building types.15 As the study notes:
• Intervention 1 offered the greatest energy
savings with buildings that had larger
conditioned floor areas and space heating and
cooling requirements and was cost-effective for
almost all building types and climate zones.
• Intervention 2 offered less than 2% energy
savings (the impacts of cool roofs alone, if
and when they were positive, were small) and
was cost-effective
in some scenarios, but the
lifetime net benefits were small compared
with those offered by increased insulation.
• Intervention 3 offered the greatest
energy
savings with larger conditioned floor areas and
space heating and cooling requirements
and
was cost-effective in some building types and
climate zones.
The study comparing code-compliant
roof
insulation and roof albedo concluded the
following:
• Code-compliant insulation provides
greater
net benefits than the cool-roof intervention in
all cases.
• Insulation levels are equally as or more
effective than “cool roofs” in achieving
energy-saving goals.
• Cool roofs tend to provide only a marginal
or slight reduction in energy use across all
modeled climate zones when installed with
traditional levels of insulation. These findings
applied to most commercial building types
with low-sloped roofs and insulation installed
entirely above deck.
The findings suggest code-compliant
insulation in most cases provides significantly
greater net benefits than cool-roof intervention
in all but a few rare cases where the insulation
intervention is not cost-effective. And despite
a modest reduction in cool-roof impacts when
combined with code-compliant insulation, the
combination of code-compliant insulation and
a cool roof provides greater benefits than either
alone. This finding suggests that when there
is an equal opportunity to either increase the
roof insulation to be code-compliant or pursue
a cool-roof project, one would be remiss to not
elect the insulation intervention, after which the
incremental economics
of installing a cool roof
tend to be lessened.16
STUDY LIMITATIONS AND
AREAS FOR IMPROVEMENT
The researchers noted challenges and limitations
that impacted their findings. For example, in
phase 1 of the ICF study “Assessing the Effects of
Local Cool Roof Policies on Urban Heat Islands,”12
researchers noted that, although the study met
the objective of developing a replicable and
scalable framework to assess the relative role of
commercial cool roofs on local urban heat islands,
these results were influenced by limitations,
including control of confounding environmental
factors, spatial separation between urban areas,
and low correlations between weather station air
temperature and urban density.8
Further, weather station air temperature
and urban density are the two variables used
to determine UHI intensity over the analysis
period. The lack of correlation between these two
variables has several implications.
• First, it suggests air temperatures recorded at
weather stations are influenced primarily by
local conditions
and to a lesser degree (or if at
all) by the nearby surrounding
areas.
• Second, it implies that urban density alone
is not a good proxy for air temperature as
anthropogenic
and environmental factors,
such as tailpipe emissions and the color
of impervious surfaces, also influence
temperature.
• Third, it implies that the margin of error in the
temporal UHI intensity
analysis is significant
in most cases to negate trends observed in
UHI over the analysis period.
Limitations pertaining to the quality and
coverage of satellite imagery also contributed
to inconclusive results.
• Satellite data was limited to 30-meter
resolution and provided less granularity for
classifying imagery, discerning between
objects, and distinguishing between land
surface colors than higher-resolution (0.5- and
1.0-meter resolution) data.
January 2025 IIBEC Interface • 25
• The geographical boundary assessed for
changes in land surface color includes cool
roofs as well as other land-use changes,
such as an increase in landscape vegetation
and possible
increased urban tree canopy.
Both options are well known and effective
strategies for UHI mitigation.
• The lack of trends directly relatable to cool roofs
can be attributed to the geographical area of
coverage and satellite
resolution and could be
a result of differences in cloud cover between
selected satellite imagery, changes in urban
land use other than from cool roofs, or loss
of reflectivity or darkening of white surfaces
(including roofs) due to surface degradation.
In phase 2, the study limitations were related
to conclusions that can be drawn from the
analysis results due to environmental factors
rather than study design. These include the
following:9
• Control of confounding environmental
factors—Two aspects common to the
referenced cities are the prevalence of local
ordinances and double-digit population
growth, both of which have potentially
interactive and/ or confounding, but
opposite impacts with UHIs. Vegetative roof
mandates and tree planting, for example, are
complementary
UHI mitigation strategies to
cool-roofing ordinances. While the impacts of
complementary UHI policies may moderate
the impacts of population growth, after city
selection, the best course of action to reduce
potential
bias is to select analysis periods that
both cover significant
installations of cool
roofs and limit the change in environmental
conditions from related UHI policies.
• Representative weather stations—
While
there is a sufficient quantity of available weather
stations,
the analysis is limited both by the
geographic availability of those used in the
CCCSP, which consisted of those generally to the
south that are in nonmountainous
areas; the
number of weather stations used in the Climate
Central study, which is limited to one urban and
three rural stations; and location of the weather
stations. While the airport station has a high
urban density, it is located close to a body of
water (river) that may exert influence over the air
temperature
in a way that counters the analysis.
RECOMMENDATIONS FOR
FUTURE RESEARCH
As part of their studies, the researchers identified
issues in which further study could increase
understanding of the benefits cool roofs might
have on UHIs and energy efficiency. They include
the following:9
• Comparing cool roofs with other strategies
for reducing the creation and impacts of
UHIs, such as increasing vegetation area
and improving the albedo of paved surfaces.
Both of these approaches have been shown
to reduce the effects of UHIs beyond that of
low-albedo commercial
roofs.
• Assessing the strength and significance of
daytime UHIs for the top 10 US cities following
the methodologies outlined in the CCCSP
study. For each analyzed city, researchers
should assess the magnitude and timing of
impact from other environmental factors that
influence UHIs over the analysis period.
• Using high-resolution GIS data to evaluate
building-level changes in white roofs as well
as changes in landscape vegetation, as both
may influence the creation and impacts of
UHIs.
• Analyzing the variability of air temperatures
over time in cities where the majority of roofs
are white to see if it has a positive impact on
the occurrence of UHIs.
POLICY IMPLICATIONS AND
CONCLUSION
The decisions by cities and building code
governing bodies to mandate reflective roofing
in certain climate zones have preempted the
economic and science-based individualized
design decisions predicated upon critical factors
such as local geography, building use, or the
roofing materials’ carbon footprint. Focusing on
the reflectivity
of roofing materials as a means of
addressing the impacts of UHIs is misplaced and
unproven.15
Therefore, the ERA recommends that federal,
state, and municipal
governments refrain from
mandating policies that require reflective-roofing
mandates until the presumed benefits of cool
roofs are compared with other strategies for
increasing energy efficiency and reducing the
effects of UHIs. Further, these comparisons must
use consistent and robust methodologies
for
evaluating other strategies known to mitigate
UHI impacts, such as increasing landscape
vegetation and improving the albedo of paved
surfaces, both of which account for many times
the total area of low-albedo commercial roofs.4
Meeting these requests would result in
the broader, more rigorous, and consistent
real-world analysis needed to assess the value
of cool roof mandates within a larger, more
comprehensive plan for addressing the impacts
of climate change.
The strategies for reducing the impact of
UHIs and boosting energy efficiency vary
widely and the impacts of cool roofs compared
with other approaches, such as installing cool
pavement, increasing
landscape vegetation
and tree planting, and implementing smart
growth policies and regulation, have not been
determined.
The Clemson University review of current
literature on cool roofs found questions that
need to be examined in depth to understand
the benefits and implications of cool roofs:
How does seasonality
impact UHI and cool roof
efficacy? How do different locations, roof types,
and climate zones impact UHIs and energy
efficiency? Should cool roof implementation
focus on roofs with the largest surface area? To
what degree does material degradation impact
the effectiveness of cool roofs? And what are the
economic and life cycle benefits of cool roofs?5
Further, although there is an abundance
of
current research that examines the impact of
cool roofs on building performance, energy
efficiency, and UHIs, there are notable gaps and
inconsistencies in their research methodologies
that limit the application of their findings in
real-world settings. These gaps and discrepancies
are significant, for the effectiveness of cool
roofs in addressing these issues depends on a
combination of factors that are unique to each city
and/or geographic location, and thus incongruous
with one-size-fits-all roof mandates.5
Similar conclusions were reached in the
three-phase ICF study “The Impact of Cool Roof
Mandates on Urban Heat Islands,”7 which found
that commercial rooftops, including
cool roofs,
are only one of many factors impacting UHIs, and
that the impact of cool roof mandates on UHI is
largely inconclusive and requires more research.
This is important information for policymakers
who may view cool roofs as a silver bullet they
can use to defend citizens against the threats of
climate change.4,6
Further, the ICF study “A Comparison of
Code-Compliant Roof Insulation and Roof
Albedo Impacts and Benefits”15 reached a similar
conclusion: there is a proper location and usage
for every roof membrane available, and the use
of cool roof does not yield the greatest
benefits
in all cases. As the ICF researchers note, “When
there is an equal opportunity to either increase
the roof insulation to be code-compliant or
pursue a cool roof project, one would be remiss
to not elect the insulation intervention, after
which the incremental economics
of installing a
cool roof tend to be lessened.”16
All too often, mandates like those some US
cities have been enacting
in regard to the use
of cool roofs on all new construction and roof
replacements limit the flexibility
to consider other
options by focusing too intently on one environmental
attribute—in this case roof reflectivity—
instead of taking a more comprehensive approach
26 • IIBEC Interface January 2025
and considering the overall sustainability
and
resilience of the system, the roof assembly. Such
restrictions limit the ability of roofing design
professionals to use their education and training
to design, specify, or recommend a particular
roof membrane,
and thereby prohibit them from
implementing the best and most sustainable
solution for the situation at hand.
Because ERA members make a variety of
roofing membranes of various colors that
are used in countless geographic locations
and building types around the country, ERA’s
members believe that the fundamental questions
about cool roofs raised in this white paper be
answered before additional mandates
prohibiting
building owners from using the roofing products
of their choice are enacted.
REFERENCES
1. Gajjar, Dhaval, and Vivek Sharma, “The Impact
of Membrane Color and Roof Albedo on Energy
Efficiency and Urban Heat Islands,” Clemson
University, report to ERA Technical Committee,
November 17, 2022.
2. ICF, “Assessing the Effects of Local Cool Roof Policies
on Urban Heat Islands,” report to ERA Technical
Committee, October 8, 2019.
3. ICF, “A Comparison of Code-Compliant Roof
Insulation and Roof Albedo Impacts and Benefits
on Energy Efficiency.” Report to ERA Technical
Committee, May 23, 2023.
4. Blum, J., and E. Thorp, “Leading Roofing
Manufacturers Request Federal Government
and Non-Governmental Organizations Perform
Updated Assessment of High Roof Albedo as
Urban Heat Island,” Letter to the General Services
Administration, November 10, 2022.
5. Gajjar, Dhaval, and Vivek Sharma, “Cool Roofs &
Sustainability,” Memo to ERA, November 17, 2022.
Will be available to view on the ERA website by
January 26, 2024.
6. ERA Technical Committee, “Overview of Critical
Literature Review of Research on Cool Roofs:
A Summary of the Impact on Energy Efficiency
and UHI,” infographic factsheet, last modified
September 23, 2022, https://epdmroofs.org/
resource/literature-
review-on-cool-roofs-uhie-a
nd-energy-
efficiency/.
7. ERA Technical Committee, “The Impact of
Cool Roof Mandates on Urban Heat Islands:
Comparative Analysis Summary of Local Cool
Roof Policies on UHI,” infographic factsheet, last
modified September 1, 2022, https://epdmroofs.
org/ resource/new-research-on-roof-albedo-
and-urban-heat-islands/.
8. ICF, “Phase I Results Presentation Baltimore,” Memo
to ERA, October 8, 2019. Will be available to view on
the ERA website by January 26, 2024.
9. ICF, “Cool Roof Heat Island Effects Research
Summary and Recommendations for Improving
Study Methods,” Memo to ERA, May 22, 2020. Will
be available to view on the ERA website by January
26, 2024.
10. ICF, “Cool Roof Heat Island Effects: Comparative
Analysis of Daytime and Nighttime UHI,” Memo to
ERA, July 30, 2021. Will be available to view on the
ERA website by January 26, 2024.
11. Michalke, T., and B. Prindell, “Assessing the Effects
of Local Cool Roof Policies on Urban Heat Islands,”
Memo to ERA, October 29, 2021. Will be available to
view on the ERA website by January 26, 2024.
12. ICF, “Assessing the Effects of Local Cool Roof Policies
on Urban Heat Islands: Review and Takeaways,”
Memo to ERA, August 24, 2021. Will be available to
view on the ERA website by January 26, 2024.
13. ASHRAE, Energy Standard for Sites and Buildings
Except Low-Rise Residential Buildings, standard
90.1–2019, Peachtree Corners, GA: ASHRAE, 2019.
14. ICC (International Code Council), International
Energy Conservation Code, Country Club Hills, IL:
ICC, 2021.
15. ERA Technical Committee, “A Comparison of
Code-Compliant Roof Insulation and Roof Albedo
Impacts and Benefits,” infographic factsheet, last
modified July 15, 2023, https://epdmroofs.org/
resource/ new-research-on-roof-albedo-insulation-
and-energy-efficiency/.
16. ICF, “A Comparison of Code-Compliant Roof
Insulation and Roof Albedo Impacts and Benefits,”
Memo to ERA, May 23, 2023. Will be available to
view on the ERA website by January 26, 2024.
ABOUT THE AUTHORS
Ellen Thorp, MA,
CAE, is the executive
director of the EPDM
Roofing Association,
whose members
manufacture products
for the roof and building
enclosure. As the
leader of the trade
association, which
has existed for over
20 years, she has
served as a trusted advisor and a pivotal leader
who has positioned the organization for growth
and strengthened its goal of representing the
manufacturers of EPDM single-
ply roofing
products and their leading suppliers. Thorp
is an intentional collaborator who structures
high-capacity coalitions to strengthen advocacy,
outreach, and engagement initiatives for
numerous organizations, regulatory agencies,
and municipal governments. She has a
bachelor’s degree in political science and a
master’s degree in education policy and has
earned the rigorous Certified Association
Executive designation from the American
Society of Association Executives.
Jason P. Wilen,
RRO, AIA, CDT, is an
architect and building
enclosure specialist
with over 30 years
of experience. He
joined Klein &
Hoffman (K&H) in
2018 and is now an
associate principal.
Before K&H, Wilen
served for 7 years
as a director with the technical services
section of the National Roofing Contractors
Association and 18 years with architectural,
forensic, and roof consulting firms. He holds
a bachelor of architecture degree from the
Illinois Institute of Technology, Chicago,
and is a licensed architect in Illinois. Wilen
provides leadership and project management
for K&H’s roof system and waterproofing
rehabilitation projects; participates with
enclosure commissioning efforts, provides
litigation support, and consulting for building
and energy code development.
Additionally,
he is a member of ASTM Committees D08,
C16, and E60 and IIBEC, and he has authored
over 25 feature articles for local and national
trade journals and magazines. In 2022, he was
awarded IIBEC’s Richard M. Horowitz Award,
honoring the best technical article published
in its technical
journal, IIBEC Interface.
ELLEN THORP, MA,
CAE
JASON P. WILEN,
RRO, AIA, CDT
Please address reader comments to
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“Letter to Editor” in the subject line, or
IIBEC, IIBEC Interface,
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Raleigh, NC 27601.
January 2025 IIBEC Interface • 27