RoofWhiteningSummary

Electricity Savings for North Carolina’s
Schools and Public Buildings by
Expedited Flat Roof Whitening Using
Limestone Paid for by Carbon Credits
from Increased Surface Reflectivity
Summary of Findings
Alvia Gaskill, Jr., President
Environmental Reference Materials, Inc.
August 2015
Environmental Reference Materials, Inc.
P.O. Box 12527
Research Triangle Park, N.C. 27709
888-645-7645, 919-544-1669
alviagaskill@yahoo.com

Abstract
In this summary of the overall report, a plan is described for reducing
air conditioning (A/C) costs for NC schools and public buildings by
expedited whitening of roofs of buildings with flat roofs that are currently
dark colored (gray to black).
Energy savings from white roofs from $0.02-0.03/square feet (SF) of
roof surface area can be achieved by roof whitening. This is $2.4-3.6
million/yr for 120 million SF of the school roofs in NC that are flat and
darkly colored. Proportionally similar savings for other government
buildings can be expected. This is net of the winter heating penalty (about a
third of gross savings) caused by reduced heating from sunlight in winter
that requires additional heating to make up the difference.
Conventional white elastomeric coatings and membranes now used
for this purpose can cost between $0.50-1.00/SF more than the traditional
dark ones for scheduled roof replacements and even more for retrofits to still
functioning roofs ($1.50-2.50/SF). As a result, payback times sometimes
exceed the lifetime of the coating or membrane or even the building itself
and thus, there is no economic incentive to whiten still functioning dark
roofs.
Finding a less expensive substitute for the standard coatings and
membranes would be advantageous and allow rapid whitening of these roofs
and immediate savings on electricity. The work described here identified
agricultural white (calcitic) calcium carbonate limestone as a suitable roof
coating material.
A 1lb (454g) layer of this material at a delivered cost of $35/metric
ton costs approximately $0.02/SF but this may be reduced significantly and
if donated to only the cost of transportation (est. $10/ton). Applied as a wet
powdered mixture, it dries in several days to form a hard white surface with
a reflectivity equivalent to that of the conventional coatings and membranes.
These surface covering materials reflect between 70-90% of incoming
sunlight when new. The limestone would reflect around 70%.
1

To determine the effectiveness of using limestone as a roof coating,
field tests were conducted between 2011-2013 using simulated roof
materials coated with 50 and 300g of limestone and other materials.
Test surfaces used to evaluate limestone and other materials were gray
concrete squares (proxy for a roof deck) and an asphalt shingle (proxy for an
asphalt concrete roof). For comparison, squares were also coated with a
name brand white elastomeric coating used on roofs. To compare
performance to white membrane roof covers, a 4-mil thick white
polyethylene sheet was attached to a concrete square and used as a proxy for
this type cover. Photographs of the test surfaces are shown in Appendix A.
The 50g limestone coatings were subjected to outdoor weathering for
two years to determine their lifetime as well as to evaluate their performance
compared to the elastomeric coating and the white polyethylene that were
not subjected to weathering.
In addition to these tests, concrete squares were coated with 0.7lb
(300g) of limestone to simulate a multi-year coating such as would be done
on building roofs. These squares were not subjected to outdoor weathering
and were used solely to assess their performance vs. the uncoated concrete.
These coated squares were tested on a tennis court and at other
locations over a 2-year period. Because equipment to measure solar
reflectivity was not available, the temperature of the surface was measured
as a proxy using a non-contact IR (infrared) thermometer.
The limestone provided almost the same cooling as the elastomeric
coating and the polyethylene sheet 20ºF lower than the uncoated concrete.
The coating on the shingle lowered the temperature by up to 50ºF.
Unlike the standard roof coatings and membranes, the limestone is
slowly eroded by rain and wind. Based on the field tests it was concluded
that a 50g coating should last for at least one year with little loss of cooling
compared to an uncoated surface and a level ten times that for 10 years
under NC weather conditions, a lifetime comparable to that of the standard
materials before they require recoating or repair.
2

To assess the cooling performance of a coating level expected to last
10 years, gray concrete squares were coated with 300g of limestone using
several levels of water and compared to an uncoated one in field tests. The
coating prepared as a cake batter-like mixture after drying consolidated to
form a hard sheet that should offer the optimum compromise in terms of
ease of application and longevity. It provided surface cooling equivalent to
that of the 50g layers.
Application on roofs of schools and public buildings could be
efficiently done by pumping the limestone water mixture from a tank on the
ground. Labor costs associated with the application can be controlled using
existing state and school employees to perform the coating. The feasibility
of doing this would have to be determined.
The limestone cost can be recovered in less than one year from
electricity savings if the labor is provided at no additional cost, resulting in
up to 9 years of net savings ($0.27/SF) compared to none for a coating or
membrane costing $0.50-2.50/SF.
Because of the low cost of this material, it could be used to extend the
lifetime of asphalt roofs delaying an expensive roof replacement. It could
also be used to determine in one summer if the conventional materials would
result in energy savings, avoiding potentially hundreds of thousands of
dollars in unnecessary resurfacing.
The roofing and coating industry may object to use of an inexpensive
substitute for their products. The limestone would not replace conventional
materials since it would be used on roofs for which no roof whitening would
be expected at all or for a very long time.
The limestone coating would not interfere with placement of rooftop
solar panels and may make them more efficient by keeping the surface
cooler.
A limestone coating does not require any maintenance. Any soiling or
biological growth will be eroded away with a fresh white surface constantly
exposed.
3

The added weight of the limestone/SF is about the same as an asphalt
shingle. It would not add significantly to the structural loading of the roof.
Limestone is porous and water will penetrate throughout the coating so it is
not a substitute for an impervious sealant. By blocking water that impacts it,
it would however, reduce the total amount of water that could reach the
underlying substrate.
Building codes may need to be changed to allow limestone as a roof
coating, although rocks and gravel are now permitted to ballast some roofs.
Warranties for shingles may be voided if a coating is applied, but the
warranty terms for other types of roofs are not known to the author and need
to be determined. Since use of the limestone will likely lengthen and not
shorten the lifetimes of existing roofs, the benefits should outweigh the risks.
Potential beneficial impacts from the roof whitening such as reducing
the Urban Heat Island effect and global warming and lowering production of
ground level ozone would be inconsequential for NC given the small
percentage of the total urban area to be whitened.
Others have also expressed concerns about feedbacks that might raise
the global temperature and reduce precipitation locally where the roofs are
employed but these conclusions have been challenged and the degree and
extent of roof whitening in these studies was not realistic.
The surface area of all air-conditioned flat roof commercial buildings
in the U.S. is less than 800 square miles, too small to have significant
impacts on these large-scale phenomena. The area of school roofs to be
covered in NC, around 4 square miles spread across the state is also too
small to have any measurable impacts.
The electricity savings would result in reduced emissions of carbon
dioxide and air pollutants by the utility supplying the electricity. Roof
whitening would reduce emissions by around 2.5 kg/m2
. For NC’s 120 M
SF of school roof surface that could be whitened, this is about 30,000 tons/yr
of carbon dioxide.
4

Some of the limestone washed or blown away will be oxidized to
carbon dioxide (CO2). The most likely mechanisms are reaction with nitric
acid from nitrogen-based fertilizer and from acid precipitation. However,
since the buildings are not located near agricultural fields and NC’s
precipitation is not acidic, the percent of limestone oxidized will likely be
low. Even if all were oxidized, the impact on net CO2 offsets would be
minimal. Other life cycle costs from mining, transportation and application
are also only a few percent in terms of CO2 emissions offset.
Because actual roofs, unlike the test squares have raised walls, much
of the limestone that was washed from these surfaces may remain in place,
or be carried away through drains or deposited in the soil nearby. Thus,
limestone eroded by wind or washed off the roofs by precipitation has no
adverse environmental consequences.
To arrive at the figures used in this report, a database of nearly 150
flat roofed public buildings in Durham and Wake Counties was compiled
along with photos of the buildings using Bing Maps. These include all
buildings under the control of the Department of Administration in Raleigh,
all public schools in Durham County, all high schools in Wake County and
all city and county buildings in Durham County. Examples of each are
shown in Appendix B along with an explanation of how the database was
constructed.
This data set is large enough to be representative of all government
and school buildings in NC and thus the results can be extrapolated to all
such buildings in this state and nationally.
Should the project proceed, a database of all NC schools and public
buildings needs to be created. Roof areas and colors can be estimated by
online mapping programs like Bing and Google Earth that were used in the
research for this plan.
Site visits to a representative number of buildings will be required to
confirm the mapped data and where necessary, the rooftop reflectivity
determined using field instrumentation. It is uncertain if all buildings will
have to be visited and the initial survey will determine how many. Buildings
with roofs suitable for coating with limestone will also need to be identified.
5

Field trials of the limestone coating should be carried out on a mix of
old and new buildings representative of the inventory of all school and
government buildings in NC. Buildings with new roofs and old ones as well
as new and old HVAC systems should be included. In this way, a range of
likely savings can be predicted.
Roof surfaces that should be considered are finished and unfinished
concrete masonry, asphalt, membranes, wood and stone. Dark roofs on 1-2
story buildings should receive priority consideration, as these are most likely
to experience the greatest electricity savings. Building engineers along with
the author will determine which roofs are suitable for the field trials.
A coating expected to last at least 2 years will be applied to the
surface using the proposed limestone water pumping method, once it has
been found to be satisfactory in small scale tests. Volunteers and/or
government employees will apply the coating.
The limestone will probably have to be purchased for full-scale
implementation or obtained from existing stockpiles maintained by the State,
but a price lower than the market one of $35/ton may be negotiated
depending on the quality of material available. Some quarries discard fines
that could be used for the roof coating and thus, the cost may be only that of
transportation, less than $10/ton. Before it is used, the limestone will be
tested to ensure it will produce a white enough surface to reflect at least 70%
of sunlight.
The electricity savings from the roof coating will be monitored for up
to one year or less if done before the start of the cooling season. If no
electricity savings are found, this will have identified a particular building as
one for which a more expensive and permanent coating would be
unwarranted. Appendix B discusses some of the options for determining
electricity savings.
Based on the results of the field studies, the limestone coating process
will be finalized and a full-scale program designed.
6

The limestone can be paid for by selling CO2 equivalent credits for
CO2 and methane emissions based on the atmospheric infrared radiation (IR)
or heat energy offset by the whitening of roofs. When the roof is made more
reflective with the white coating, less sunlight is absorbed and less IR is
emitted into the atmosphere.
Because a mathematical relationship exists between IR emitted by
these greenhouse gases and their mass in the air and IR is fungible, the
reduction in IR emitted by the roofs is the same as not having a certain mass
of these gases in the air during the lifetime of the roof. Thus, although no
CO2 is directly removed from the air from roof whitening, its global
warming impact is muted.
The algorithm used to calculate this credit is described in detail in the
overall report and summarized in Appendix C.
The potential value of these credits can be estimated based on carbon
offsets now trading in two markets in the U.S., the Regional Greenhouse Gas
Initiative operated by northeastern states and the California market
administered by the state Air Resources Board.
Current prices for carbon credits in these markets range from $5.50-
10/metric ton of CO2 equivalent. At $7/metric ton of CO2 equivalent and for
a 10-year contract, the estimated lifetime of the coating, this will yield
around $0.01/SF net of all life cycle emissions produced and the cost of
administration and monitoring for the 135 M SF of school roof area, around
$1.5 M. Similar credits can be calculated for methane emissions from
animal waste lagoons.
To further expedite the roof whitening, credits for existing white roofs
from schools and public and private buildings can be sold with the private
sources donating their credits to public education and the funds used to
whiten more roofs. For example, if the estimated 100 M SF of existing
commercial white roof area in NC were used to generate carbon credits as
above, this would provide enough funds ($1 million) to pay for the coating
of all of the applicable NC school building roofs if the limestone price is
discounted by a factor of two.
7

To accomplish this, a database could be created for the white roofs of
all publicly and privately owned white roofed buildings in NC. This would
be done after obtaining commitments from the owners to sell the credits to
e.g. Duke Energy or some other party with the stipulation that the proceeds
be donated to public education in NC.
By stipulating that a white roof from photographs is at least 50%
reflective, existing roofs that are white will not need to be measured except
for roof areas. Due to the small value of the credits for individual buildings,
they will have to be aggregated to generate sufficient credits for sale. It
should be possible to complete the inventory of all existing white roofed
buildings in NC by the end of calendar year 2015.
Use of existing projects to claim a carbon credit is generally
considered a violation of the additionality rule in carbon trading markets (the
projects must be additional and not already done for some other purpose
such as regulatory compliance or green building certification or to save on
energy). However, an exception can be made if doing so will result in new
carbon offsets that would be the intention here.
Acceptance of reflectivity-based credits in the carbon markets will be
necessary as will be identification of entities willing to purchase the credits.
One potential purchaser is Duke Energy. If a positive response to this
proposal from the State is received, Duke will be contacted regarding their
interest in the carbon credit sales as well as in the potential energy savings.
The scientific and economic evidence for these claims are presented in
detail in the body of this report. Although some field-testing will be
required to confirm the assumptions made, we believe all of the applicable
roofs of NC schools and public buildings can be whitened in less than one
year and the program expanded nationally and internationally with NC the
proving ground for this innovative and cost effective energy saving measure.
Adopting the white roof/carbon credit strategy can establish North
Carolina as a leader in climate change mitigation, moving it ahead of
California, Florida and Hawaii in implementation of white roofs and
establishing the first carbon-trading program based on reflective surfaces.
8

The support of state and local governments is needed for this concept
to become a reality. Funding is also a requirement for field tests and
implementation of the proposed program. Any assistance in these areas
would be highly desirable.
9

Contents
1.1 Addressing school and state building funding problems 1
1.2 Electricity savings from white roofs on NC school buildings 1
1.3 Cost of roof whitening with conventional materials 2
1.4 Use of limestone to whiten building roofs 2
1.5 Results of field tests comparing limestone with 3
conventional materials
1.6 Lifetime of the limestone coating 6
1.7 Evaluation of 10-year coating with limestone 7
1.8 Application of the limestone/recovery of costs 8
1.9 Other benefits of the limestone coating 9
1.10 Objections from the roofing/solar industry 9
1.11 Maintenance, weight of limestone on roofs, effect 9
on leakage and building codes and warranties,
Energy Star certification
1.12 Environmental impacts 12
1.13 Implementation 13
1.13.1 Database of building roofs 13
1.13.2 Field trials 13
1.14 Paying for limestone with carbon credits 14
1.14.1 Calculation of credits 14
1.14.2 Use of existing white roofs 16
1.15 Schedule/funding 17
1.16 About the author 17
1.17 References and notes 19
Appendix A Photographs of limestone and other materials A-1
applied to simulated roof surfaces
Appendix B Database of public buildings used in this research B-1
B.1 Department of Administration (DOA) buildings
in Raleigh
B.1.1 Identification of buildings and roof areas B-1
and colors
B.1.2 Electricity usage for 1-2 story DOA buildings B-17
B.2 Public and charter schools B-18
B.3 City and county buildings B-31
B.4 Monitoring of electricity savings B-35
Appendix C Calculation of carbon credits from roof whitening C-1
i

Summary
1.1 Addressing school and state building funding problems
State government buildings in Raleigh are in need of major upgrades
and maintenance as are the more than 2500 public schools and other public
buildings around the state (1). One potential source of funds to address this
is savings on electricity use and one area in which savings could be found is
in making these buildings more energy efficient with regard to air
conditioning (A/C) use.
This could free up funds for other uses such as performing needed
maintenance on existing buildings including those that would make the
buildings more energy efficient. Thus, any strategy that cost effectively
reduces A/C electricity expenses for schools and state and local governments
In this summary of the overall report, a plan is described for reducing
A/C costs for NC schools and public buildings by expedited whitening of
roofs of buildings with flat roofs that are currently dark colored (gray to
black). Aged (3 years and older) white surfaces of roofs reflect 50-60% of
sunlight compared to 10-25% for dark surfaces and thus reduce the amount
of heat energy from absorbed sunlight entering the occupied portions of
these structures and the demand for A/C (2).
1.2 Electricity savings from white roofs on NC school buildings
It is estimated from a national survey of commercial buildings that in
NC overall energy savings from white roofs from $0.02-0.03/square feet
(SF) of roof surface area can be achieved by roof whitening (3). This is in
the range of $2.4-3.6 million/yr for 120 million SF of the school roofs in NC
that are flat and darkly colored (4). Proportionally similar savings for other
government buildings can be expected.
1

This is net of the winter heating penalty (about a third of gross
savings) caused by reduced heating from sunlight in winter that requires
additional heating to make up the difference. A/C electricity savings for
buildings from roof whitening are calculated based on the roof area over the
inhabited space below, the “conditioned” roof area (CRA). They generally
only apply to the floor directly beneath the roof.
1.3 Cost of roof whitening with conventional materials
Conventional white elastomeric coatings and membranes now used
for this purpose can cost between $0.50-1.00/SF more than the traditional
dark counterparts for scheduled roof replacements can and even more for
retrofits to still functioning roofs ($1.50-2.50/SF). As a result, payback
times sometimes exceed the lifetime of the coating or membrane or even the
building itself and thus, there is no economic incentive to whiten still
functioning dark roofs (5-7).
This is evident in aerial surveys of Los Angeles and San Francisco
where per regulations white roofs are required on flat roofed buildings, only
3-8% of those over 5000 SF were identified as having a reflectance >40%,
indicative of a slow replacement cycle or non compliance (8). Nationally, it
is estimated that at most 10% of the roofs of commercial flat roofed
buildings are white (9). Similar figures were estimated by the author in the
reviews of roofs of public buildings in Durham and Wake counties.
1.4 Use of limestone to whiten building roofs
Finding a less expensive substitute for the standard coatings and
membranes would be advantageous and allow rapid whitening of these roofs
and immediate savings on electricity. The work described here identified
agricultural white (calcitic) calcium carbonate limestone as a suitable roof
coating material.
A 1lb (454g) layer of this material at a delivered cost of $35/metric
ton (10) costs approximately $0.02/SF but this may be reduced significantly
and if donated to only the cost of transportation (est. $10/ton). Applied as a
wet powdered mixture, it dries in several days to form a hard white surface
with a reflectivity equivalent to that of the conventional coatings and
2

membranes. These surface covering materials reflect between 70-90% of
incoming sunlight when new. The limestone would reflect around 70%.
1.5 Results of field tests comparing limestone with conventional materials
To determine the effectiveness of using limestone as a roof coating,
field tests were conducted between 2011-2013 using simulated roof
materials coated with limestone and other materials.
The test surfaces used to evaluate limestone and other materials were
gray concrete squares (proxy for a roof deck) and an asphalt shingle (proxy
for an asphalt concrete roof). The uncoated square is shown in Figure 1
(Appendix A). Its estimated reflectivity to sunlight is 25%. Many of the
building roofs for NC schools and other public buildings identified in the
online mapping done appear to be about this color.
Most of the testing was performed on squares that had been coated
with whitewash, a mixture of calcium hydroxide with water. Whitewash
converts into limestone after application, in these cases to 50g on the
surface. Figure 2 shows a square with a 50g limestone coating.
For comparison, squares were also coated with a name brand white
elastomeric coating used on roofs.
Figure 3 shows a concrete square coated with 287 Solar-Flex White
Roof Coating, an elastomeric coating with a rated reflectivity to sunlight of
86% (11).
To compare performance to white membrane roof covers, a 4-mil
thick white polyethylene sheet was attached to a concrete square (Figure 4)
and used as a proxy for this type cover. It probably has a solar reflectivity
similar to that of the elastomeric coating. In other field tests, it produced
equivalent performance to thicker layers of polyethylene.
Figure 5 shows an asphalt shingle to which 50g of limestone applied
as whitewash are on half of the shingle. Limestone’s performance on this
material was evaluated by comparing the coated and uncoated sections. The
uncoated asphalt probably has a reflectivity to sunlight of less than 10%
since it is black.
3

The 50g limestone coatings were subjected to outdoor weathering for
two years to determine their lifetime as well as to evaluate their performance
compared to the elastomeric coating and the white polyethylene that were
not subjected to weathering.
In addition to these tests, concrete squares were coated with 0.7lb
(300g) of limestone (not whitewash) to simulate a multi-year coating such as
would be done on building roofs. These squares were not subjected to
outdoor weathering and were used solely to assess their performance vs. the
uncoated concrete.
Figure 6 shows one of the squares after coating with 0.7lb (300g) of
limestone.
Because limestone applied as whitewash and limestone applied as
limestone both adhered equally well to the surfaces tested, it can be
concluded that limestone would in general if the surface is rough enough for
it to form a bond. Whitewash has traditionally been used on the sides of
buildings because it can be prepared as a soluble coating for application with
a brush to a vertical surface. Limestone is nearly 150 times less soluble (12-
14) than calcium hydroxide, but because it would only be used on flat
surfaces in the proposed program, the solubility issue is not as important.
These coated squares were tested on a tennis court and at other
locations over a 2-year period. Because equipment to measure solar
reflectivity was not available, the temperature of the surface was measured
as a proxy using a non-contact IR (infrared) thermometer. Since all of the
materials are expected to have the same thermal emissivity, around 0.9 (they
all emit IR at about the same rate), their reflectivities should correlate well
with the temperature comparisons.
The surface temperatures were measured periodically during the day
under clear skies, including the times between 10am and 4pm where the
maximum solar heating would occur. Even in March and April, significant
temperature differences were observed between the coated and uncoated
surfaces.
4

An example is seen in the data from April 7, 2011 from testing on a
tennis court at 3:40pm.
Air 85ºF
Gray concrete 116ºF
Limestone 96ºF
Solar Flex 97ºF
Polyethylene 98ºF
The limestone provided almost the same cooling as the elastomeric
coating and the polyethylene sheet 20ºF lower than the uncoated concrete.
A summary of other tests showed a similar performance compared to
the gray concrete:
Limestone 15-20ºF cooler
Solar Flex 17-20ºF cooler
Polyethylene 19-20ºF cooler
Similar performance was achieved for the asphalt shingle coated with
limestone, with much greater relative cooling observed since the reflectivity
of the asphalt is assumed to be around 10%. These results are from July 27,
2012 at 1:20pm.
Air 98ºF
Uncoated shingle 170ºF
Coated shingle 120ºF
Limestone 14 mos. exposure 118ºF
Limestone added 111ºF
The limestone added square was one freshly coated with limestone
while the one exposed for 14 months had been coated with whitewash. The
coating on the shingle lowered the temperature by 50ºF. The limestone-
coated squares were 23-30ºF cooler, with the lower value attributable to
visible loss of the coating during outdoor exposure.
5

1.6 Lifetime of the limestone coating
Unlike the standard roof coatings and membranes, the limestone is
slowly eroded by rain and wind. Observations of the area around the
exposure site revealed tiny flakes of limestone. Repeated wet and dry cycles
cause the surface to become chalky and the powdery surface material is
more easily removed by wind and rain.
After two years of exposure, the limestone showed it had lost more
cooling power due to further reductions in surface reflectivity as shown in
these data from April 27, 2013 at 12:30pm. Figure 7 shows the loss in the
coating for the exposed limestone. Even though it had lost nearly 90% of
the original coating, it still was cooler than the uncoated concrete by 24ºF.
Air 76ºF
Limestone unexposed 88ºF
Limestone 2 years exposure 98ºF
Similar results were found for the asphalt shingle (Figure 8). By July
16, 2013, around 18 months after it was coated, it had lost most of the
original coating, but still produced significant cooling compared to the
uncoated shingle in these results from 12:30pm.
Air 91ºF
Based on these results it was concluded that a 50g coating should last
for at least one year with little loss of cooling compared to an uncoated
surface. However, the goal is not to apply a coating level that will only last
one or two years. The results suggest that if 50g is lost per year, then a
coating level ten times that should last for 10 years under NC weather
conditions, a lifetime comparable to that of the standard materials before
they require recoating or repair.
6

Since the primary mechanism for removal is rain, in regions that get
less rainfall than NC (around 50 inches per year) such as the southwest and
California (around 15-20 inches per year), the coating should last twice as
long (15).
Weathering tests for coatings are performed by manufacturers to
obtain Energy Star certification and in some cases to meet regulatory
requirements that are based on the Energy Star standard of a minimum initial
65% reflectivity (7) degrading to no lower than 50%. These involve 3-year
outdoor tests. However, these are done to determine the degree of soiling
and darkening of the surface that tends to stabilize after 3 years. The
limestone does not darken appreciably after outdoor exposure, so a 3-year
test is meaningless. It is also unlikely that the limestone reflectivity would
decrease below 50% during its lifetime.
Lawrence Berkeley National Laboratory (LBNL) has developed a
laboratory test to simulate 3-year’s of exposure to replace the current tests
required for Energy Star approval of coatings and membranes (16). The
accelerated weathering test only takes several days to complete. It could be
used to confirm the estimated limestone coating lifetime without lengthy
field trials by running the test longer.
1.7 Evaluation of 10-year coating with limestone
To assess the cooling performance of a coating level expected to last
10 years, gray concrete squares were coated with 300g of limestone and
compared to an uncoated one in field tests.
Three different ways of coating the squares were used. In one, 6
individual layers were added, allowing each one to dry before applying the
next (Figure 9). Experience with whitewash indicates that this creates a
stronger material (17). In the second, a mixture was prepared with the
minimum amount of water needed to create a paste-like material (Figure 10).
In the third, more water was used to produce a cake batter-like mixture
(Figure 6).
7

The first method would be too labor intensive to use on roofs. The
second produced a more porous product that may not be as durable long
term. The third, after drying consolidated to form a hard sheet that should
offer the optimum compromise in terms of ease of application and longevity.
Results of field comparisons of all three are shown below from July
24, 2013 at 3:15pm. Except for the coating prepared with little water, all
produced similar cooling to that of the 50g layers. The rough surface of the
paste coating probably contributed to a higher temperature due to absorption
of sunlight due to re-reflection within the matrix.
Air 93ºF
Layered limestone 99ºF
Limestone paste 102ºF
Limestone cake batter 97ºF
Limestone (50g) 97ºF
Limestone 2 years exposure 108ºF
Limestone as whitewash 101ºF
1.8 Application of the limestone/recovery of costs
A program to manually cover flat roofs of 250 M SF of buildings in
New York City with elastomeric coatings using rollers and brushes to reduce
peak demand has whitened around 6 million SF but as of 2013 has taken 5
years and involved over 5000 volunteers plus some paid workers (2, 18-20).
This is less than the same roof area as the total for all the schools in Durham
and Wake counties. At the rate at which this is being done, it will take more
than 200 years to complete the coating. To do the same for NC’s schools
and public buildings will require a different approach.
Application on roofs of schools and public buildings could be
efficiently done by pumping the limestone water mixture from a tank on the
ground. Labor costs associated with the application can be controlled using
existing state and school employees to perform the coating. The feasibility
of doing this would have to be determined.
8

The limestone cost can be recovered in less than one year from
electricity savings if the labor is provided at no additional cost, resulting in
up to 9 years of net savings ($0.27/SF) compared to none for a coating or
membrane costing $0.50-2.50/SF.
1.9 Other benefits of the limestone coating
Because of the low cost of this material, it could also be used to
extend the lifetime of asphalt roofs that become brittle due to exposure to
heat and UV radiation from sunlight. This could delay an expensive roof
replacement until funds become available for a more permanent retrofit with
the conventional coatings and membranes. It could also be used to
determine in one summer if these more expensive surfaces would result in
energy savings, avoiding potentially hundreds of thousands of dollars in
unnecessary resurfacing.
1.10 Objections from the roofing/solar industry
The roofing and coating industry may object to use of an inexpensive
substitute for their products, but as a practical matter, the limestone would
not be replacing them in the market. The buildings to be considered are ones
for which no roof whitening would be expected at all or for a very long time.
Thus, it’s not a matter of limestone vs. elastomeric coatings or membranes;
it’s a matter of limestone vs. nothing. The limestone coating would not
interfere with placement of rooftop solar panels and may make them more
efficient by keeping the surface cooler (2).
1.11 Maintenance, weight of limestone on roofs, effect on leakage and
building codes and warranties, Energy Star certification
A limestone coating does not require any maintenance. Washing of
the limestone surface would not be required and could not be performed
anyway. Any soiling or biological growth will also be eroded away with a
fresh white surface constantly exposed.
9

The added weight of the limestone/SF is about the same as an asphalt
shingle. It would not add significantly to the structural loading of the roof.
Limestone is porous and water will penetrate throughout the coating so it is
not a substitute for an impervious sealant. While it is wet it will weigh more
and may take several days to completely dry after a rain event. By blocking
water that impacts it, it would however, reduce the total amount of water that
could reach the underlying substrate.
Building codes may need to be changed to allow limestone as a roof
coating, although rocks and gravel are now permitted to ballast some roofs.
Warranties for shingles may be voided if a coating is applied, but the
warranty terms for other types of roofs are not known to the author and need
to be determined. Since use of the limestone will likely lengthen and not
shorten the lifetimes of existing roofs, the benefits should outweigh the risks.
Some building owners may desire to meet Energy Star requirements
for cool roofs using the limestone coating. The current standard is that the
aged coating should have a 3-year aged reflectivity of 50% regardless of its
composition (7). Although the limestone should meet this limit as
previously noted, this will require further investigation if the project
proceeds.
1.12 Environmental impacts
A review of current modeling research concluded that potential
beneficial impacts from the roof whitening such as reducing the Urban Heat
Island effect and global warming and lowering production of ground level
ozone would be inconsequential for NC given the small percentage of the
total urban area to be whitened (21-25).
Perhaps surprisingly, there are objections to the use of roof whitening.
One study calculated that increasing use of white roofs globally without first
insulating buildings would result in excessive winter heating penalties
causing more energy to be used for space heating than would be saved on
A/C (26). That would not occur for NC.
10

Others have also expressed concerns about feedbacks that might raise
the global temperature and reduce precipitation locally where the roofs are
employed (27-30) but these conclusions have been challenged (31).
These modeling studies found that massive whitening of all roofs in
the U.S. or globally including residential buildings in urban areas results in a
stabilization of the atmosphere over the cities due to the extra sunlight
reflected upwards. This cools the air and reduces upward convection (air
movement) resulting in less cloud formation and ultimately less
precipitation. The white roofs also reduced the evaporation of water, also
contributing to less cloud formation.
All of these models unrealistically assumed the surface reflectivity of
both residential and commercial roofs could be increased to between 70-
90% and they would remain so, i.e., no weathering of the surface. For
aesthetic reasons and due to local ordinances, residential sloped roofs are not
suitable candidates for roof whitening.
Residential roofs can be brightened using specially coated shingles
that raise the reflectivity to around 40% from an initial of around 10-20%
(2), but the impact of this on meteorology and climate has not been
separately investigated. Because commercial building roofs are around 20%
of the total roof area of all buildings (9), the impact on precipitation and air
temperature of whitening only the roofs of commercial buildings would be
far less or none at all.
The CRA of all air-conditioned flat roof commercial buildings in the
U.S. is less than 800 square miles (3), too small an area to have significant
impacts on these large scale phenomena. The area of school roofs to be
covered in NC, around 4 square miles spread across the state is also too
small to have any measurable impacts.
The electricity savings would result in reduced emissions of carbon
dioxide (CO2) and air pollutants by the utility supplying the electricity. Roof
whitening would reduce emissions by around 2.5 kg/m2
(3). For NC’s 120
M SF of school roof surface that could be whitened, this is about 30,000
tons/yr.
11

Some of the limestone that is washed or blown away will likely be
oxidized to CO2. How much will depend on its fate after leaving the roof.
In studies of the lifecycle of agricultural limestone and its impact on CO2
emissions (32), it was found half of the limestone applied to agricultural soil
was oxidized back to CO2 before the remainder reached the ocean. Nitric
acid produced from nitrogen-based fertilizer was the primary oxidant.
Since there are no agricultural fields near the buildings, little of the
limestone should be oxidized by this mechanism. NC rainfall is not acidic
like in some northeastern states and thus it would not be oxidized by this
means either. Even if all were oxidized, the impact on net CO2 offsets
would be minimal. Other life cycle costs from mining, transportation and
application are also only a few percent in terms of CO2 emissions offset.
As noted, the limestone will be slowly eroded from the surface by
wind and rain. The extent to which this will occur is not certain as the
concrete and asphalt surfaces used in the field tests did not have raised walls
as is the case with most flat roofs. Consequently, much of the limestone that
was washed from these surfaces may on actual roofs, remain in place, or be
carried away through drains. Field-testing is necessary to determine the fate
of the limestone.
Most of it will likely accumulate in soil nearby the building and
eventually either be taken up by plants or bound into soil or be carried down
storm drains to a wastewater treatment plant and removed as sludge or
discharged into a river to follow the same pathway as from farm applied
limestone. The soil near the buildings is not expected to be regularly treated
with fertilizer therefore much less limestone would be oxidized to CO2.
Thus, limestone eroded by wind or washed off the roofs by
precipitation has no adverse environmental consequences.
12

1.13 Implementation
1.13.1 Database of building roofs
To arrive at the figures used in this report, a database of nearly 150
flat roofed public buildings in Durham and Wake Counties was compiled
along with photos of the buildings using Bing Maps. These include all the
buildings under the control of the Department of Administration in Raleigh,
all public schools in Durham County, all high schools in Wake County and
all city and county buildings in Durham County. Examples of each are
shown in Appendix B along with an explanation of how the database was
constructed.
This data set is large enough to be representative of all government
and school buildings in NC and thus the results can be extrapolated to all
such buildings in this state and nationally.
Should the project proceed, a database of all NC schools and public
buildings needs to be created. Roof areas and colors can be estimated by
online mapping programs like Bing and Google Earth that were used in the
research for this plan.
Site visits to a representative number of buildings will be required to
confirm the mapped data and where necessary, the rooftop reflectivity
determined using field instrumentation. It is uncertain if all buildings will
have to be visited and the initial survey will determine how many. Buildings
with roofs suitable for coating with limestone will also need to be identified.
1.13.2 Field trials
Field trials of the limestone coating should be carried out on a mix of
old and new buildings representative of the inventory of all school and
government buildings in NC. Buildings with new roofs and old ones as well
as new and old HVAC systems should be included. In this way, a range of
likely savings can be predicted.
13

Roof surfaces that should be considered are finished and unfinished
concrete masonry, asphalt, membranes, wood and stone. Dark roofs on 1-2
story buildings should receive priority consideration, as these are most likely
to experience the greatest electricity savings. Building engineers along with
the author will determine which roofs are suitable for the field trials.
A coating expected to last at least 2 years will be applied to the
surface using the proposed limestone water pumping method, once it has
been found to be satisfactory in small scale tests. Volunteers and/or
government employees will apply the coating.
The limestone will probably have to be purchased for full-scale
implementation or obtained from existing stockpiles maintained by the State,
but a price lower than the market one of $35/ton may be negotiated
depending on the quality of material available. Some quarries discard fines
that could be used for the roof coating and thus, the cost may be only that of
transportation, less than $10/ton. Before it is used, the limestone will be
tested to ensure it will produce a white enough surface to reflect at least 70%
of sunlight.
The electricity savings from the roof coating will be monitored for up
to one year or less if done before the start of the cooling season. If no
electricity savings are found, this will have identified a particular building as
one for which a more expensive and permanent coating would be
unwarranted. Appendix B discusses some of the options for determining
electricity savings.
Based on the results of the field studies, the limestone coating process
will be finalized and a full-scale program designed.
1.14 Paying for limestone with carbon credits
1.14.1 Calculation of credits
The limestone can be paid for by selling CO2 equivalent credits for
CO2 and methane emissions based on the atmospheric infrared radiation (IR)
or heat energy offset by the whitening of roofs. When the roof is made more
reflective with the white coating, less sunlight is absorbed and less IR is
emitted into the atmosphere.
14

Because a mathematical relationship exists between IR emitted by
these greenhouse gases and their mass in the air and IR is fungible, the
reduction in IR emitted by the roofs is the same as not having a certain mass
of these gases in the air during the lifetime of the roof. Thus, although no
CO2 is directly removed from the air from roof whitening, its global
warming impact is muted.
The algorithm used to calculate this credit is described in detail in the
overall report and summarized in Appendix C. It is a modification of the
one proposed by LBNL (22).
LBNL and the California Energy Commission have also proposed
such credits in memoranda to the State Department to include national and
international use of such offsets (9). Thus, this is not the first time such an
idea has been put forth.
The potential value of these credits can be estimated based on carbon
offsets now trading in two markets in the U.S.
The Regional Greenhouse Gas Initiative (RGGI) is a cap and trade
program involving nine Northeastern states in which utilities are allowed to
bid for credits online issued by the states to meet a CO2 emissions limit (33).
Carbon credits began trading in the California market in 2013 established by
the state and administered by the Air Resources Board (34).
Current prices for carbon credits in these markets range from $5.50-
10/metric ton of CO2 equivalent (35, 36). At $7/metric ton of carbon
dioxide equivalent and for a 10-year contract, the estimated lifetime of the
coating, this will yield around $0.01/SF net of all life cycle emissions
produced and the cost of administration and monitoring for the 135 M SF of
school roof area, around $1.5 M. Similar credits can be calculated for
methane emissions from animal waste lagoons.
15

1.14.2 Use of existing white roofs
To further expedite the roof whitening, credits for existing white roofs
from schools and public and private buildings can be sold with the private
sources donating their credits to public education and the funds used to
whiten more roofs. For example, if the estimated 100 million SF of existing
commercial white roof area in NC were used to generate carbon credits as
above, this would provide enough funds ($1 million) to pay for the coating
of all of the applicable NC school building roofs if the limestone price is
discounted by a factor of two.
To accomplish this, a database could be created for the white roofs of
all publicly and privately owned white roofed buildings in NC. This would
be done after obtaining commitments from the owners to sell the credits to
e.g. Duke Energy or some other party with the stipulation that the proceeds
be donated to public education in NC.
By stipulating that a white roof from photographs is at least 50%
reflective, existing roofs that are white will not need to be measured except
for roof areas. Due to the small value of the credits for individual buildings,
they will have to be aggregated to generate sufficient credits for sale. It
should be possible to complete the inventory of all existing white roofed
buildings in NC by the end of calendar year 2015.
Use of existing projects to claim a carbon credit is generally
considered a violation of the additionality rule in carbon trading markets (the
projects must be additional and not already done for some other purpose
such as regulatory compliance or green building certification or to save on
energy) (37). However, an exception can be made if doing so will result in
new carbon offsets that would be the intention here (38).
Acceptance of reflectivity-based credits in the carbon markets will be
necessary as will be the identification of entities willing to purchase the
credits. One potential purchaser is Duke Energy. If a positive response to
this proposal from the State is received, Duke will be contacted regarding
their interest in the carbon credit sales as well as in the potential energy
savings.
16

1.15 Schedule/funding
The scientific and economic evidence for these claims are presented in
detail in the body of this report. Although some field-testing will be
required to confirm the assumptions made, we believe all of the applicable
roofs of NC schools and public buildings can be whitened in less than one
year and the program expanded nationally and internationally with NC the
proving ground for this innovative and cost effective energy saving measure.
Adopting the white roof/carbon credit strategy can establish North
Carolina as a leader in climate change mitigation, moving it ahead of
California, Florida and Hawaii in implementation of white roofs and
establishing the first carbon-trading program based on reflective surfaces.
The support of state and local governments is needed for this concept
to become a reality. Funding is also a requirement for field tests and
implementation of the proposed program. Any assistance in these areas
1.16 About the author
Alvia Gaskill, Jr., 60 is the president of Environmental Reference Materials,
Inc., PO Box 12527 Research Triangle Park, NC 27709. 888-645-7645
919-544-1669, alviagaskill@yahoo.com
The company produces and sells soil, paint and oil standards to
laboratories performing lead paint and predictive maintenance testing. The
company is also an e-procurement vendor for the state of NC and sells
standards to the state laboratory of public health. Mr. Gaskill assisted NC
DENR in developing regulations for the used oil industry in NC and has
provided expert testimony in federal criminal cases involving waste
disposal.
He has carried out research on global warming mitigation
technologies for the last 15 years including development of geoengineering
strategies for reducing solar radiation by stratospheric aerosols and
increasing the reflectivity of large natural areas like deserts.
17

His proposals have been the subject of computer modeling and
analyses by others (39, 40) and included in reports on geoengineering issued
by the Royal Society in London (41) and the Intergovernmental Panel on
Climate Change (42) as well as various books. He was the first to suggest
the use of CO2 credits for surface whitening in 2004 (43).
He has been interviewed by the New York Times, CNN Money, the
Christian Science Monitor (43), Canadian Public Radio and the Daily
Telegraph among others about his work and has appeared in a
geoengineering documentary on the Discovery Channel and in an
independent film, Owning the Weather along with other scientists in the
field.
He has a BA in Chemistry from UNC-CH (1974) and a Master of
Science in Public Health, UNC-CH (1978). Prior to starting his company in
1989, he worked at RTI International from 1979-1989 on evaluation of the
quality of measurements used in air pollution control technologies and later
on development of environmental test methods for hazardous wastes, some
of which are widely used today.
18

1.17 References and notes
1. A. Jones-Hoyle, SeveralstateagenciesmullmoveoutsideofdowntownRaleigh,
TriangleBusinessJournal,February2,2014,
http://www.bizjournals.com/triangle/print-edition/2014/02/14/several-
state-agencies-mull-move.html?page=all
2. A Practical Guide to Cool Roofs and Cool Pavements, January 2012,
Global Cool Cities Alliance and R20 Regions of Climate Action,
www.coolroofkit.org
3. R. Levinson and H. Akbari, Potential benefits of cool roofs on
commercial buildings: conserving energy, saving money, and reducing
emission of greenhouse gases and air pollutants, Energy Efficiency
3:53–109, 2010, doi:10.1007/s12053-008-9038-2
This is how the cost savings for North Carolina schools were
estimated. In the simulation performed by Levinson and Akbari (2010),
schools were considered offices and savings ranged from $0.01 to 0.05/SF.
If it is assumed 50% of the schools in North Carolina in their study were
built before 1980, an average figure of $0.03/SF can be expected. We
estimate there are 120 million SF of school flat roof area in North Carolina
suitable for white coating (Appendix B). This would predict annual energy
savings of $3.6 million.
Because many new schools have been built in North Carolina since
the study data was generated (2003) if the percentage of new schools has
increased to 75%, then apportioning the $0.02 and 0.03/SF savings the
figure becomes 0.0075 + 0.015 = $0.023/SF. This would then yield an
estimated annual energy savings of $2.4 million. However, the estimate of
75% may be excessive and the actual predicted savings closer to the study
average.
19

Summary statistics for NC from this study are presented below, noting
these are based on 2003 data. NC schools represent about 15% of the total
CRA in NC.
Total commercial flat roof area 1.37 billion SF
Total CRA 979 million SF
Electricity cost $/kWh $0.069
Gas cost $/therm $1.25
Cooling savings kWh/m2
4.91
Heating penalty $/therm/m2
0.0604
Net savings $/SF $0.024/SF
CO2 kg/m2
reductions 2.52
4. Satellite and airplane photographs of buildings and on screen
measurements determined that the average school in NC has a coatable
roof area of around 65,000 SF accounting for equipment and other roof
obstructions. After eliminating sloped and metal roof buildings and those
already with white roofs, the figure of 120 million is arrived at.
5. DDC Cool and Green Roofing Manual, NYC Dept. of Design and
Construction, Office of Sustainable Design, June 2005-June 2007, Cool
Green Roof Man.pdf,
http://www.nyc.gov/html/ddc/html/ddcgreen/home.html
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National Laboratory, March 2014,
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20

9. H. Akbari and A. Rosenfeld, Broadening the U.S. climate commitment to
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10. The cost of $35/ton is based on prices listed by Shelter Creek Lime and
Stone of Maple Hill, NC of $27/ton and $8/ton was added to cover
transportation and other costs such as milling of the limestone to a
powdered form. This company operates a quarry in Jones County and
supplies much of the agricultural limestone used in NC. Their website is
now down and this estimate is from several years ago, but is probably
in line with current prices for agricultural limestone. If the project
proceeds, more current and complete estimates will be obtained.
11. HE287SF, 287 Solar-Flex White Roof Coating, Technical Data Sheet,
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Segundo CA 90245-2754, www.henry.com
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precipitation.php
21

16. M. Sleiman, T.W. Kirchstetter, P. Berdahl, H.E. Gilbert, S. Quelen, L.
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According to this work, the strategic plan for this program intends that
250 million SF of roofs (25% of all the flat roofs in New York City) be
whitened by 2020. However, this is clearly unrealistic. The goals outlined
in the long-term plan for New York City in reference 19 indicate that the
goal is to whiten 10 M SF by 2025 at a rate of 1 M SF per year, about the
rate at which this is being done (reference 20).
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Low Carbon Future, Mayor’s Office of Long-Term Planning and
Sustainability, OneCity.pdf, p. 82, nyc.gov/BuiltToLast,
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22

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24

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absence of the CDM (i) the proposed voluntary measure would not be
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systematically not enforced and that non-compliance with those
requirements is widespread in the country/region, or (iii) the project will
lead to a greater level of enforcement of the existing mandatory
policy/regulation.”
“Clean Development Mechanism: An arrangement under the Kyoto Protocol
allowing industrialised countries (Annex I countries) with a greenhouse gas
reduction commitment to invest in projects that reduce emissions in
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expensive emission reductions in their own countries.”
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25

42. L. Clarke et al, Assessing Transformation Pathways. In: Climate Change
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geoengineering options to prevent abrupt and long-term climate change,
Environmental Reference Materials, Inc., June 29, 2004,
http://www.see.ed.ac.uk/~shs/Cliamte%20change/Geo-
politics/Gaskill%20DOE.pdf
44. M. Clayton, How white roofs shine bright green, Christian Science
Monitor, October 3, 2008,
http://features.csmonitor.com/innovation/2008/10/03/how-white-roofs-
shine-bright-green/
45.Willowtec Utility Tracker Energy Management System,
http://energy.willowtec.com/reports.php
46. Facts and Figures 2012-2013, Division of School Business, Financial
and Business Services, NC Department of Public Instruction, Raleigh,
NC 27601-2825, December 2012,
http://www.ncpublicschools.org/docs/fbs/resources/data/facts
figures/2012-13figures.pdf, accessed 1-14-14.
47. Highlights of the North Carolina Public School Budget, Division of
School Business, North Carolina Department of Public Instruction,
February 2013,
http://www.ncpublicschools.org/docs/fbs/resources/data/highlights
/2013highlights.pdf, accessed 1-14-14.
48. 2008-2009 Selected Financial Data, Division of School Business
Financial and Business Services, Public Schools of North Carolina, State
Board of Education, Department of Public Instruction,
www.ncpublicschools.org/fbs/resources/data/, accessed 2010.
26

49. Energy Service Company,
http://en.wikipedia.org/wiki/Energy_service_company
50. Determining energy savings using utility bills: a winning method for
ESCOs, Abraxis Energy, 3rd International Congress on Energy
Efficiency and Renewable Energy Sources, April 26, 2007
http://www.energyvortex.com/files/DeterminingEnergySavings
UsingUtilityBills.pdf
51. GAO, “Energy savings: performance contracts offer benefits, but
vigilance is needed to protect government interests, 2005,
http://gao.gov/cgi-bin/getrpt?GAO-05-340
52. P. Campra, Global and local effect of increasing land surface albedo
as a geo-engineering adaptation/mitigation option: a study case of
Mediterranean greenhouse farming in climate change-research and
technology for adaptation and mitigation, pp. 453-474, In: Research and
Technology for Adaptation and Mitigation, J Blanco and H Kheradmand,
ed., ISBN: 978-953-307-621-8, InTech, 2011,
http://www.intechopen.com/books/climate-change-research-and-
technology-foradaptation-and-mitigation/global-and-local-effect-of-
increasing-land-surface-albedo-as-a-geo-engineeringadaptation-
mitigation
53. P. Campra, M. Garcia, Y. Canton and A. Palacios-Orueta, Surface
temperature cooling trends and negative radiative forcing due to land use
change toward greenhouse farming in southeastern Spain, Journal of
Geophysical Research, 113(D18109, 10), 2008, doi:
10.1029/2008JD009912
54. I. Muñoz, P. Campra and A.R. Fernández-Alba, Including CO2-
emission equivalence of changes in land surface albedo in life cycle
assessment. Methodology and case study on greenhouse agriculture,
International Journal of Life Cycle Assessment, 15, 672–81, 2010, DOI
10.1007/s11367-010-0202-5
27

55. National Solar Radiation Data Base, NSRDB update-TMY3: 1991-2005
update, alphabetical list by state and city, NREL, 2005,
http://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3/
56. National Solar Radiation Data Base, 1991-2010 Statistics
http://rredc.nrel.gov/solar/old_data/nsrdb/1991-
2010/statistics/dsf/723140.dsf
28

Appendix A
Photographs of limestone and other materials
applied to simulated roof surfaces
Figure 1. Uncoated gray concrete square, approximately 12 in x 12 in
A-1

Figure 2. Gray concrete square coated with 50g of limestone
A-2

Figure 3. Gray concrete square coated with HE287SF, 287 Solar-Flex White
Roof Coating
A-3

Figure 4. Gray concrete square covered with 4-mil white polyethylene sheet
A-4

Figure 5. Asphalt shingle coated with 50g of limestone (top) and uncoated
(bottom)
A-5

Figure 6. Gray concrete square coated with 0.7 lb (300g) of limestone
A-6

Figure 7. Limestone coated concrete square after two years exposure
(bottom right). Unexposed limestone at same coating level (upper right).
Uncoated gray square (left).
A-7

Figure 8. Limestone coated asphalt shingle after 18 months exposure
A-8

Figure 9. Limestone applied in 6 layers to gray concrete
A-9

Figure 10. Limestone applied to gray concrete with minimum amount of
water
A-10

Appendix B
Database of public buildings used in this research
B.1 Department of Administration (DOA) buildings in Raleigh
B.1.1 Identification of buildings and roof areas and colors
The DOA buildings in the Raleigh area under the management of the
Department of Administration (DOA) were identified from maps provided
by the DENR and from Willowtec (45), a company contracted by the State
to track electricity usage for these and related buildings.
Using these maps and listings and other information from DENR,
Willowtec, Google Earth, Bing Maps and other sources, buildings that could
be amenable to roof whitening were identified. The state government
buildings surveyed included those in the State Government Complex as well
as others.
Sloped roof buildings were eliminated. The remaining buildings were
then analyzed to determine which ones had (a) flat roofs, (b) light colored
roofs (c) white roofs and (d) dark or black roofs. The areas suitable for
coating were also determined.
Information on the roofs (flat or sloped, roof material and color) and
roof areas of most of these buildings is not readily available. This was
obtained from satellite and airplane photographs of the buildings from Bing
Maps.
Light colored roofs include those that appear to consist of white, tan
or light gray colored concrete or some other surface material, while white
roofs are defined here as those with a white coating or membrane surface.
In comparing Google Earth and Bing map photos taken from satellites
(aerial views) with that from airplane photography taken at about a 45º angle
(“Bird’s Eye views” in the lexicon of global mapping), it was noticed both
the Google Earth and Bing aerial images were sometimes inaccurate with
regard to roof surface color.
B-1

In some cases, roofs that were actually light-colored, i.e., tan or white,
appeared blue or gray on the satellite images and much lighter in color on
the airplane images. This is probably due to the time of day at which the
photographs were taken and to shifts in the visible spectrum from satellite
imaging.
It is known that the satellite used to obtain ground photographs passes
over the U.S. at the same time each day, but the amount of light received at
the surface will vary seasonally and due to cloud cover. Likewise, the
airplane photography could be subject to similar artifacts due to the sun
angle and clouds. For these reasons, the colors reported for the roofs in this
evaluation need to be confirmed by an on-site assessment.
An example of this is the Motor Fleet Management Building shown in
Figure 11. In the aerial view (top), it appears to have a dark gray roof, but in
the Bird’s Eye view (bottom), the roof is much lighter in color.
Due to the color inaccuracies, aerial (satellite) images were used to
confirm locations and estimate roof surface areas while determinations of
roof color were made using the Bird’s Eye views. Because the aerial views
are generally straight down, the areas are more easily estimated than from
the Bird’s Eye views.
B-2

Figure 11. Motor Fleet Management, 1915 Blue Ridge Road, Raleigh, NC
27607
B-3

Other representative examples of state government buildings in the Raleigh
area are shown below.
Figure 12. Textbook Warehouse, 3905 Reedy Creek Road, Raleigh, NC
27607
This is a one-story building with a gray flat roof with 35,000 SF of total
coatable surface area.
B-4

Figure 13. Old Education Building, 114 West Edenton Street, Raleigh, NC
27603 (Dept. of Justice Building)
This is a six-story building with a light brown flat roof. The total coatable
surface area is 20,000 SF. Note surrounding construction in progress in the
Bird’s Eye view.
B-5

Figure 14. New Revenue Building, 501 North Wilmington Street, Raleigh,
NC
This seven-story building has a gray flat roof with a total coatable surface
area of 35,000 SF.
B-6

Figure 15. Bath Building, 306 North Wilmington Street, Raleigh, NC 27601
This is a five-story building with a light gray flat roof and a large HVAC
pod in the middle and two smaller ones on the corners. The total coatable
surface area is 20,000 SF.
B-7

Figure 16. Old Textbook Warehouse, 215 West Lane Street, Raleigh, NC
27603
Now listed as the Old Records Building, this is a one-story building with a
dark gray flat roof with around 20,000 SF of total coatable surface area.
B-8

Figure 17. Personnel Development Center, 101 West Peace Street, Raleigh,
NC 27603
This is a one-story building with a light gray flat roof and five HVAC pods
down the center and 15,000 SF of total coatable surface area.
B-9

It must be noted that aerial views are newer, by several years than the
Bird’s Eye views, no doubt due to the greater cost of airplane compared to
satellite photography. This is apparent in the discrepancies noticed in some
of the two photos for each building roof. The only way to resolve this is by
onsite visits which is not possible without climbing on the roof. If the
project proceeds, site visits will be necessary to obtain accurate roof colors
and dimensions.
The roof area potentially suitable for whitening or for claiming carbon
credits was estimated using the aerial satellite scale on Bing Maps, after
omitting HVAC equipment that could not be coated and raised sloped
surface areas and rounded to the nearest 5000 SF (Table 1). The map
estimates were compared with actual building square footage reported by the
DOA (45) after adjusting for the number of stories (Table 2).
Given inherent errors associated with such measurements, the roof
areas so calculated are not intended to be exact or relied upon for final
determination of costs of roof coverings or potential electricity savings and
carbon offsets. However, based on other knowledge of the buildings, the
estimates are probably accurate to ± 20%.
Some of the discrepancies in surface area between those measured
using Bing Maps and reported by the DOA are negative due to reductions in
usable surface area after subtracting HVAC and other equipment on the
roofs that would not be coated. In those cases where the map estimates were
higher than the DOA’s, the DOA’s were used going forward. The highest
estimates vs. the DOA were for the Reedy Creek Research Laboratory,
because this unit was part of a larger building and could not be separately
identified.
Of these buildings, the 1-2 story structures are the most likely to
benefit due to reduced electricity usage on a per building basis by whitening
roofs, while the others would not benefit as much, but could still qualify for
carbon credits (Table 3). As noted previously, most of the electricity
savings and temperature reduction occurs in the story immediately below the
roof with less impact experienced in those further below.
B-10

Table 1. Roof data for DOA buildings in Raleigh area from Bing Maps
Roof, coatable
Building Stories Roof color square feet
2. Old Education Building 6 light brown 20,000
3. Old Revenue Building 6 white and gray 10,000
4. Court of Appeals 4 gray 7,500
5. Justice Building 5 light gray 8,000
6. New Revenue Building 7 gray 35,000
10. Caswell Building 6 gray 8,000
11. Shore Building 4 gray 5,000
13. Oral Hygiene Building 2 black 1,500
14. Cooper Memorial Building 6 gray 7,500
16. Albemarle Building 11 light gray 10,000
17. Bath Building 5 gray 20,000
20. DENR Administration* 4 gray 20,000
22. Old Central Heat Plant 2 green 1,000
54. Central Heat Plant 2 off white 10,000
23. Caswell Square Heat Plant 1 white 1,000
24. Old Records Building** 2 dark gray 20,000
26. Building Systems/HVAC 1 light gray 2,500
Shop
31. Phillips Building 1 light gray 15,000
32. State Capitol Police 1 white 5,000
(Womack)
33. Facility Management Bldg 1-2 dark gray 15,000
34. Personnel Development Ctr. 1 light gray 15,000
58. Construction Services Bldg. 2 gray 20,000
59. Legislative Office Building 5 light gray 25,000
60. Brown Rogers Building 4 gray 3,000
61. Plumbing/Electrical Shops 1 white 5,000
62. Landscape Services Office 1 dark gray 5,000
63. New Education Building 7 gray, tan 25,000
64. NC Museum of History 5 gray 30,000
65. Motor Fleet Management 1 light gray 15,000
66. Textbook Warehouse 1 gray 35,000
67, 74-83, 91, 92.
Garner Road Complex 1-2 gray, tan 50,000
B-11

Table 1. Roof data for DOA buildings in Raleigh area from Bing Maps
(cont’d)
Roof, coatable
68. State Surplus Warehouse 1 gray 35,000
84. New SBI Laboratory 5 gray 20,000
85. Research Laboratory**** 1 black 70,000
(Reedy Creek Road)
87. Facility Management 1 gray 3,500
Greenhouse Offices
101. Administration Building 6 gray 25,000
103 Archdale Building 15 light gray 15,000
104. Dobbs Building 5 gray 25,000
105. State Archives & Library*** 2 tan 30,000
113. Chiller Plant #2 1 gray 500
117. Agriculture Building and 6 gray 20,000
Old Museum of Natural Sciences*****
Other State
Buildings
1. NC State Lab of Public Health 3-4 white 30,000
2. NC DOT (Highway Bldg) 5-6 gray 40,000
3. Central Prison 2-6 tan, gray, black 70,000
Total: 764,000
The numbering system is based on a DENR list.
*Replaced Old YWCA Building **Originally listed as Old Textbook
Warehouse ***Not included in total as may be leased space and much less
than 70,000 ****Originally listed as both Museum of History & Archives &
History Bldg *****Old Museum of Natural Sciences also known as the
Agriculture Building Annex
B-12

Table 2. Comparison of roof areas from Bing Maps estimates with those
from the DOA
Bing Maps DOA Percent
Building Stories area (SF) area (SF) difference
2. Old Education Building 6 20,000 28,995 -31
3. Old Revenue Building 6 10,000 28,998 -66
4. Court of Appeals 4 7,500 13,987 -46
5. Justice Building 5 8,000 13,700 -42
6. New Revenue Building 7 35,000 42,686 -18
10. Caswell Building 6 8,000 13,082 -39
11. Shore Building 4 5,000 8,929 -44
13. Oral Hygiene Building 2 1,500 8,813 -83
14. Cooper Memorial Building 6 7,500 9,489 -21
16. Albemarle Building 11 10,000 17,488 -43
17. Bath Building 5 20,000 23,760 -16
20. DENR Administration 4 20,000 unknown ----
22. Old Central Heat Plant 2 1,000 unknown ----
23. Caswell Square Heat Plant 1 1,000 unknown ----
54. Central Heat Plant 2 10,000 10,457 -4
24. Old Records Building 2 20,000 18,348 9
26. Bldg. Systems/HVAC Shop 1 2,500 2,958 -15
31. Phillips Building 1 15,000 14,136 -6
32. State Capitol Police (Womack) 1 5,000 6,344 -21
33. Facility Management Bldg 1-2 15,000 17,200 -19
34. Personnel Development Ctr 1 15,000 13,250 -2
58. Construction Services Bldg 2 20,000 22,953 -13
59. Legislative Office Building 5 25,000 unknown ----
60. Brown Rogers Building 4 3,000 2,842 +6
61. Plumbing/Electrical Shops 1 5,000 8,778 -22
62. Landscape Services Office 1 5,000 unknown ----
63. New Education Building 7 25,000 45,920 -50
64. NC Museum of History 5 30,000 38,020 -21
64. Motor Fleet Management 1 15,000 14,698 +2
66. Textbook Warehouse 1 35,000 53,298 -16
67, 74-83, 91, 92
Garner Road Complex 1-2 50,000 182,089 -73
68. State Surplus Warehouse 1 35,000 41,164 -15
B-13

Table 2. Comparison of roof areas from Bing Maps estimates with those
from the DOA (cont’d)
Bing Maps DOA Percent
Building Stories area (SF) area (SF) difference
84. New SBI Laboratory 5 20,000 26,614 -25
85. Research Laboratory 1 70,000 18,000 +289
(Reedy Creek Road)
87. Facility Management 1 3,500 2,500 +40
Greenhouse Offices
101. Administration Building 6 25,000 33,579 -26
104. Dobbs Building 5 25,000 41,709 -40
105. State Archives & Library 2 30,000 73,799 -59
113. Chiller Plant #2 1 500 3,000 -83
117. Agriculture Bldg./Museum 6 20,000 25,634 -28
Annex
Other State
Buildings
1. State Lab Public Health 3-4 30,000 unknown ----
45. NC DOT (Highway Bldg) 5-6 40,000 unknown ----
46. Central Prison 2-6 70,000 unknown ----
Total: 764,000
Percent difference = (Bing Maps – DOA)/DOA
One and two story buildings are also more representative of school
buildings, which comprise a much greater percentage of government
buildings than do office buildings in NC. The 1-2 story buildings shown in
Table 3 account for 37% of the total estimated surface area.
B-14

Table 3. Roof colors and coatable surface areas for 1-2 story buildings under
DOA management in Raleigh
Roof, coatable
23. Caswell Square Heat Plant 1 white 1,000
24. Old Records Building 2 dark gray 18,348
Shop
32. State Capitol Police 1 white 5,000
(Womack)
34. Personnel Development Ctr. 1 light gray 13,250
54. Central Heat Plant 2 off white 9,000
58. Construction Services Bldg. 2 gray 20,000
61. Plumbing/Electrical Shops 1 white 5,000
67, 74-83, 91, 92.
85. Research Laboratory* 1 black 18,000
(Reedy Creek Road)
Greenhouse Offices
105. State Archives & Library 2 tan 30,000
Total: 284,000
The more darkly colored the roof, the more effective the novel coating
could be in reducing A/C usage, so in Table 4, the buildings from the
previous table with dark roofs are listed.
B-15

Table 4. Dark roofed 1-2 story buildings under DOA management in
Raleigh
Roof, coatable
24. Old Records Building 2 dark gray 18,348
Shop
34. Personnel Development Ctr 1 light gray 13,250
58. Construction Services Bldg 2 gray 20,000
67, 74-83, 91, 92.
85. Research Laboratory 1 black 18,000
(Reedy Creek Road)
Greenhouse Offices
105. State Archives & Library 2 tan 30,000
Total: 264,000
These are the buildings most likely to benefit in terms of reduced A/C
usage from covering their roofs with a white reflective surface. They should
be among the first candidates for a field test of the limestone coating. In
addition, other buildings with lighter roofs and buildings with more than 2-
stories should also be included as one of the outcomes of a field study would
be to identify those buildings that could benefit from electricity savings from
a more permanent white roof without having to spend the money to find out.
B-16

B.1.2 Electricity usage for 1-2 story DOA buildings
Electricity usage for buildings under DOA management can possibly
be used to predict the cost due to A/C and with it potential savings from
installation of white roofs. The way in which electricity savings have
usually been estimated from use of white roofs is with computer simulations.
Here, an attempt was made to determine electricity costs and savings using
data from electric bills for individual buildings reported by Willowtec. If
successful, this approach could be used for all buildings in the proposed
program.
The cost of electricity from A/C is not easily separated from other
expenses in reports published by the DOA. This is complicated even further
when the heat transfer liquid is supplied by an offsite chiller plant and the
fans and ventilation system are in the building of interest as is true for some
of the buildings in downtown Raleigh. This may artificially lower the
reported costs estimated for A/C for some of these buildings.
Because these electric bills are dated the first day of the month, the
actual usage is for the previous month. Hence, the bill for July is actually
for electricity used in June. To compare heating and cooling months, the
averages for December, January, February and March were compared with
those for June, July, August and September, taking into consideration that
the bills were offset by one month from the usage.
In NC, the cooling season is usually from June-September and thus
comparing the difference in electricity use during these months with use
during the winter should provide an estimate for A/C use assuming other
electricity use remains constant. Thus, averages were taken for January,
February, March and April and compared to those for July, August,
September and October.
B-17

An analysis of electric bills comparing cooling months with non-
cooling months showed only $0.05/SF attributable to A/C. It was concluded
that for buildings in the State Government Complex, most of the A/C costs
were associated with the chiller plant suggesting that any roof whitening
done to these buildings would be reflected in lower costs for that plant more
than for individual buildings. In the simplest approach to determining
savings, the chiller plant bills for July year over year could be examined
with the impact of increasing white roof areas seen in declining electricity
charges.
B.2 Public and charter schools
To determine the area of school building roofs suitable for whitening
for purposes of increasing energy efficiency and sale of carbon offsets, an
examination of the NC school system is required.
There are 2526 public and charter schools in NC according to 2012-13
figures (46, 47): 1834 or 72.6% are elementary (grades PK-8), 413 (16.3%)
are secondary (grades 9-12), 98 (3.9%) are combined and 108 (4.3%) are
charter schools. A charter school is a privately run school required to follow
state policies and receives state funding but isn’t administered by county or
city school boards. The public schools are organized into 100 county and 15
city units, also known as school districts or LEAs (Local Education
Agencies). NC has 100 counties.
This list does not include other private schools that aren’t charter
schools, but probably represents more than 95% of all primary and
secondary education schools in NC. Public and private universities,
community colleges and technical schools are not included in this analysis
with the exception of community colleges in Durham and Wake counties.
Total enrollment is nearly 1.5 million students with Wake County the
largest with nearly 150,000. Wake County’s daily membership, as the state
calls it, makes it larger than that of Philadelphia. Wake’s large enrollment,
along with other rapidly growing areas along the I-85 corridor is indicative
of the fact that NC, with a population of over 9.5 million (greater than
Michigan) is now the 10th
largest state in population, making it an excellent
candidate for an energy efficiency program such as the one proposed here.
B-18

The ten largest school systems by enrollment (rounded to the nearest
1000) are:
Wake 151,000 Durham 33,000
Mecklenburg 140,000 Gaston 31,000
Guilford 73,000 Cabarrus 30,000
Forsyth 53,000
Cumberland 52,000
Union 41,000
Johnston 33,000
These ten total nearly 640,000 or 44% of the entire state enrollment.
By comparison, Pamlico County, where the author attended elementary and
high school is the seventh smallest with 1393 enrolled, exceeding only Clay,
Graham, Hyde, Jones, Tyrell, Elkin and Weldon City. Thus, NC consists of
a mix of large and small school districts with an average enrollment of
around 8000 excluding the top 10.
The overall administration of public schools in NC is by the Dept. of
Public Instruction along with the State Board of Education. County and city
school boards oversee schools at the local level by hiring administrators,
teachers and staff and paying for services including utilities. Funding comes
from a combination of state, federal and local sources. Due to
incompleteness of information, some figures are quoted from 2011-12 and
some from 2012-13.
2011-12 Expenditures:
State $ 7.6 billion 63%
Federal $ 1.7 billion 14%
Local $ 2.7 billion 23%
Total $12.0 billion 100%
Of these, salaries and benefits for teachers and other employees were
$9.8 billion or 82% of operating expenses, while school buses cost $500
million and textbooks $26 million. The total of these, $10.3 billion, leaves
$1.7 billion for other operating expenses. In the 2012-13 figures, $239
million was allocated for school administration, which would be expected to
include utilities (water, gas and electricity).
B-19

While state funding increased in 2012-13 to $7.74 billion, federal aid
declined to $856 million. Federal funding has varied over the last 6 years
due to extraordinary funding under the American Recovery Act (ARRA) and
the Race to the Top program. Federal funding is more typically around 7%
of the total as it was for 2012-2013. With the decrease in federal funding
and increase in students year over year, this has strained the overall system
according to the Dept. of Public Instruction. Thus, a program to increase
energy efficiency could be beneficial.
Electricity bills for individual schools are not available online.
However, a line item total for all public utility and energy services was
included in summary reports prepared by the Dept. of Public Instruction
(48).
For the most recent period available, 2008-2009, $290,000,000
(rounded to the nearest ten million) was spent on these services with an
additional $4 million for charter schools. Since these included water and
natural gas and electricity used was not broken out by month, it is
impossible to directly estimate the spending for A/C.
It should be noted most public schools do not operate year round,
although activities are held during summer months that would use electricity
such as summer school and various camps. As most of the A/C costs should
be incurred during June-August when the schools are not in session, the
impact of reducing A/C demand during these months needs to be studied
further.
Schools in Durham and Wake County, NC were chosen for the
electricity and roof analysis. All of the Durham County schools were
included to arrive at an estimate of the potential impact on an entire school
district. Only high schools in Wake County were included along with
Durham and Wake Technical Community Colleges.
The results of these analyses are shown in Tables 5 and 6. The
mapping approach used for state government buildings in Raleigh was used
to determine stories, roof colors and SF of coatable roof area.
Representative examples are shown below.
B-20

Hillside High School in Durham, NC is a relatively new high school
consisting of a series of interconnected one and two story buildings with
light gray flat roofs. The total coatable surface area is 145,000 SF. This
includes large surface structures that appear to be HVAC equipment.
B-21

Lowes Grove Middle School in Durham, NC consists of three
interconnected one and two-story buildings with gray and tan flat roofs with
a total coatable surface area of 100,000 SF.
Hope Valley Elementary School in Durham, NC consists of several
interconnected one-story buildings with light gray flat roofs. The total
coatable surface area is 70,000 SF.
B-22

Lakewood Elementary School in Durham, NC consists of several
interconnected one and two story buildings with white and light gray flat
roofs. The total coatable surface area is 80,000 SF.
Pearsontown Elementary School in Durham, NC consists of several
interconnected one and two-story buildings with tan to light gray flat roofs
that show evidence of soiling. The total coatable surface area is 70,000 SF.
B-23

C.C. Spaulding Elementary School in Durham, NC consists of several
interconnected one and two-story buildings with dark gray flat roofs. The
total coatable surface area is 25,000 SF.
Athens Drive High School in Raleigh, NC consists of several
interconnected one and two story flat roofed buildings. The roofs are mostly
gray in color with one that is white. The total coatable surface area is
150,000 SF.
B-24

Sanderson High School in Raleigh, NC consists of a series of
interconnected flat roof one and two story buildings. The roofs are gray in
color, with two that are white. The total coatable surface area is 150,000 SF
with 17,000 SF white.
Enloe High School in Raleigh, NC consists of a series of
interconnected flat roof one and three-story buildings. The roofs are tan and
gray in color with parts of two white. The total coatable surface area is
160,000 SF.
B-25

Southwest Raleigh Magnet High School in Raleigh, NC consists of a
series of interconnected flat roof one and two story buildings. The roofs are
white in color. The total coatable surface area is 175,000 SF.
With ~2500 public schools in NC, the 42 in Durham are about 1.7%
of the total. If Durham schools are representative of the entire system
(excluding Durham Tech and the Public Schools Warehouse), the total flat
or slightly sloped roof surface area of all public schools is around 160
million square feet or nearly 6 square miles. Based on the estimates (3) of
around 1 billion SF of flat roofed commercial buildings in NC, schools
represent around 15% of the total, making them the largest single category
of flat roofed buildings in NC and probably the nation.
A similar analysis can be done based on total SF/school where in
Durham County the total area is 2,797,500 SF. This is 66,600 SF/school. If
this is the average for the entire state, then the total SF statewide is 166
million, about the same as for the other estimate. With the uncertainties in
the methodology used to arrive at the estimates of surface area, it can be
assumed the roof area of NC public schools is at least 150 million SF.
It is further assumed 10% (15 million SF) are already white and
another 10% are constructed of metal or some other material not suitable for
the program (15 million SF). The figures for Durham and Wake County
schools show that around 5-10% of these roofs are white.
B-26

This leaves 120 million SF and that is the figure used in calculating
coating costs. The 10% assumed to already be white is used separately in
calculating carbon offsets and also in combination with the 120 million not
already white that could be made white, a total of 135 million SF.
Assuming 75% of utility and energy services costs are due to
electricity ($218 million) and 50% to operation of equipment and lighting
not related to heating or cooling ($109 million), this leaves $109 million for
heating and cooling. It is also assumed annual A/C expenses are 50% of this
total ($55 million).
It is further assumed during June-September A/C use increases the
total electricity bill by 50% vs. that of non-cooling/non heating months and
all of this is incurred during June-September. This results in a monthly A/C
charge of $13.75 million for June-September. Based on 150 million SF of
roof surface, this results in $0.37/SF/yr due to A/C. Any improvements in
building energy efficiency such as decreasing heat input into occupied parts
of the buildings by increasing the SR of the roofs will reduce this $0.37/SF
figure.
If white roofs could decrease electricity use by $0.03/SF (the average
predicted for NC (3), making all roofs of schools in these counties white
would result in an annual cost savings of around $100,000 for Durham
County schools and around $70,000 for Wake County high schools alone.
B-27

Table 5. Roof data for Durham County Schools from Bing Maps
Roof, coatable
School Stories Roof color square feet
Other Buildings
1. Durham Tech 1 light to dark gray 150,000
2. Durham Public Schools 1 white 125,000
Warehouse
Total 275,000
High Schools
1. Hillside 1-2 light gray 145,000
2. Jordan 2-3 off white, light gray 120,000
3. Northern 1-2 light gray 145,000
white 20,000
4. Riverside 1-2 off white 150,000
5. Southern 1-2 light gray 165,000
Total 745,000
Middle/Secondary Schools
1. Brogden 2 gray, tan 75,000
2. Carrington 1 off white 80,000
3. Chewning 1 off white 110,000
4. Githens 1 tan 20,000
5. Lakeview Secondary 1 white 25,000
6. Lowes Grove 1-2 gray, tan 100,000
7. Neal 1-2 off white 100,000
8. W.G. Pearson 1-3 light to dark gray 25,000
9. Rogers Herr 1-2 light gray 65,000
10. Shepard 1 brown, light gray 70,000
Total 670,000
B-28

Table 5. Roof data for Durham County Schools from Bing Maps (cont’d)
Roof, coatable
School Stories Roof color square feet
Elementary Schools
1. Bethesda 1 yellow 15,000
2. Burton 1-2 light gray, black 45,000
3. Creekside Elementary 1 green, gray 7,500
4. Easley 1-2 tan 5,000
5. Eastway 1 light gray 50,000
6. Eno Valley 1 off white, light gray 75,000
7. Fayetteville Street 1-2 light gray 40,000
8. Forestview 1 light gray 80,000
9. Glenn 1 light gray 50,000
10. R.N. Harris 1 gray, white 45,000
11. Hillandale 1 light gray 70,000
12. Hope Valley 1 light gray 70,000
13. Holt 1-2 light gray 40,000
14. Lakewood 1-2 white, light gray 80,000
15. Little River 1-2 gray 75,000
16. Mangum Elementary 1-2 white, light gray 35,000
17. Merrick Moore 1-2 light gray 55,000
18. Morehead Montessori 1 white 30,000
19. Oak Grove 1 light gray 80,000
20. Parkwood 1-2 off white, tan 40,000
21. W.G. Pearson 1 white 60,000
22. Pearsontown 1-2 tan, light gray 70,000
23. E.K. Powe 1-2 light to dark gray 30,000
24. Southwest 1 off white, tan 70,000
25. Y.E. Smith 1 white 30,000
26. C.C. Spaulding 1-2 dark gray 25,000
27. George Watts 2-3 white, gray 20,000
Total 1,317,500
Other
1. Durham School of Arts 1-3 white/gray 65,000
Overall Total 3,072,500
B-29

Table 6. Roof data for Wake County Schools from Bing Maps
Roof, coatable
Community Colleges Stories Roof color square feet
1. Wake Tech
a. Main Campus 1-2 off white/tan/gray 200,000
b. Health Science Campus 2-4 gray 40,000
c. Northern Wake Campus 2 white 40,000
d. Western Wake Campus 1 black 25,000
e. Beltline Education Center 1 light gray 130,000
f. Public Safety Education 1 off white 15,000
Campus
g. Eastern Wake Education 1 gray 0
Center
Total 450,000
Roof, coatable
High Schools Stories Roof color square feet
1. Apex 1 off white, tan, 120,000
white, black
2. Athens Drive 1-2 gray 150,000
3. Broughton 1-3 gray 70,000
4. Cary 1-2 gray, dark brown 120,000
5. East Wake 1-2 tan, gray, white 150,000
6. Enloe 1, 3 tan, gray, white 160,000
7. Garner 1-2 gray, off white 160,000
8. Green Hope 1-3 off white, gray 120,000
9. Knightdale 1-3 gray 160,000
10. Leesville Road 1-2 tan, light gray 200,000
11. Millbrook 1-2 gray 160,000
12. Panther Creek 1, 3 gray 100,000
13. Sanderson 1-2 gray 133,000
white 17,000
14. Southwest Raleigh 1-2 white 175,000
15. Wake Forest Rolesville 1-3 light gray, white 150,000
16. Wakefield 1-3 white 100,000
Total 2,245,000
Total including Wake Tech 2,695,000
B-30

RoofWhiteningSummary

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