Reflective surfaces (climate engineering)

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make creating solar-reflective shingles a particular challenge, causing asphalt shingles to have solar reflectances of only 4%-26%. When these roofs are designed to reflect increased amount of solar radiation, the urban heat island effect can be reduced through the reduced need for cooling costs in the summer. Though a more reflective roof can lead to higher heating costs in the colder months, studies have shown that the increased winter heating costs are still lower than the summer cooling cost savings. To satisfy the consumer demands for darker colors which still reflect significant amounts of sunlight, different materials, coating processes, and pigments are used. Since only 43% of light occurs in the visible light spectrum, reflectance can be improved without affecting color by increasing the reflectance of UV and IR light. High surface roughness can also contribute to the low solar reflectances of asphalt shingles, as these shingles are made of many small approximately spherical granules which have a high surface roughness. To decrease this, other granule materials are being investigated, such as flat rock flakes, which could reduce the reflectance inefficiencies due to surface roughness. Another alternative is to coat the granules using a dual coat process: the outer coating would have the desired color pigment, though it may not be very reflective, while the inner coating is a highly reflective titanium dioxide coating.

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trade-offs that are often unaccounted for. Cool roofs have been found to be particularly effective for certain areas during summertime. However, during winter, these same urban adaptation strategies, when deployed in northerly locations, further cool the environment, and consequently require additional heating to maintain comfort levels. “The energy savings gained during the summer season, for some regions, is nearly entirely lost during the winter season,” Georgescu said. In Florida, and to a lesser extent southwestern states, there is a very different effect caused by cool roofs. “In Florida, our simulations indicate a significant reduction in precipitation," he said. "The deployment of cool roofs results in a 2 to 4 millimeter per day reduction in rainfall, a considerable amount (nearly 50 percent) that will have implications for water availability, reduced stream flow and negative consequences for ecosystems. For Florida, cool roofs may not be the optimal way to battle the urban heat island because of these unintended consequences.” Overall, the researchers suggest that judicious planning and design choices should be considered in trying to counteract rising temperatures caused by urban sprawl and greenhouse gases. They add that “urban-induced climate change depends on specific geographic factors that must be assessed when choosing optimal approaches, as opposed to one-size-fits-all solutions.”

387:'s "Guidelines for Selecting Cool Roofs" on the subject of cool roof maintenance: "As a cool roof becomes dirty from pollution, foot traffic, wind-deposited debris, ponded water, and mold or algae growth, its reflectance will decrease, leading to higher temperatures. Especially dirty roofs may perform substantially worse than product labels indicate. Dirt from foot traffic may be minimized by specifying designated walkways or by limiting access to the roof. Steep sloped roofs have less of a problem with dirt accumulation because rainwater can more easily wash away dirt and debris. Some cool roof surfaces are “self-cleaning” which means they shed dirt more easily and may better retain their reflectance. Cleaning a cool roof can restore solar reflectance close to its installed condition. Always check with your roof manufacturer for the proper cleaning procedure, as some methods may damage your roof. While it is generally not cost effective to clean a roof just for the energy savings, roof cleaning can be integrated as one component of your roof's routine maintenance program. It is therefore best to estimate energy savings based on weathered solar reflectance values rather than clean roof values." 295:(annual cooling energy savings less annual heating energy penalty) associated with cool roofs (meaning that one will need to use more energy to heat the living space due to reduction in heat from sunlight in winter.) However, this applies only to those areas with low winter temperatures – not tropical climates. Also, homes in areas receiving snow in winter months are unlikely to receive significantly more heat from darker roofs, as they will be snow-covered most of the winter. A response paper titled "Cool Roofs and Global Cooling," by researchers in the Heat Island Group at Lawrence Berkeley National Laboratory, raised additional concerns about the validity of these findings, citing the uncertainty acknowledged by the authors, statistically insignificant numerical results, and insufficient granularity in analysis of local contributions to global feedbacks. 542:(LBNL) measured and calculated the reduction in peak energy demand associated with a cool roof's surface reflectance. LBNL found that, compared to the original black rubber roofing membrane on the Texas retail building studied, a retrofitted vinyl membrane delivered an average decrease of 24 °C (43 °F) in surface temperature, an 11% decrease in aggregate air conditioning energy consumption, and a corresponding 14% drop in peak hour demand. The average daily summertime temperature of the black roof surface was 75 °C (167 °F), but once retrofitted with a white reflective surface, it measured 52 °C (126 °F). Without considering any tax benefits or other utility charges, annual energy expenditures were reduced by $ 7,200 or $ 0.07/square foot.(This figure is for energy charges as well as peak demand charges). 616:

stringent as their appliance standard and does not include the additional components of a roof (i.e. roof structure, fire rated barriers, insulation, adhesives, fasteners, etc.). A disclaimer is posted on their website "Although there are inherent benefits in the use of reflective roofing, before selecting a roofing product based on expected energy savings consumers should explore the expected calculated results that can be found on the Department of Energy's "Roof Savings Calculator" website at www.roofcalc.com. Please remember the Energy Savings that can be achieved with reflective roofing is highly dependent on facility design, insulation used, climatic conditions, building location, and building envelope efficiency."

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system; a building's information is verified by a Green Globes-approved and trained licensed engineer or architect. To qualify for a rating, roofing materials must have a solar reflectance of at least 0.65 and thermal emittance of at least 0.90. As many as 10 points may be awarded for 1–100 percent roof coverage with either vegetation or highly reflective materials or both. The basis in physics of a high emittance is quite questionable, since it merely describes a material which easily radiates infrared wavelength heat to the environment, contributing to the greenhouse effect. Highly reflective, low-emittance materials are much better at reducing energy consumption.

380:’s "Guidelines for Selecting Cool Roofs": “Cool roofs must be considered in the context of your surroundings. It is relatively easy to specify a cool roof and predict energy savings, but some thinking ahead can prevent other headaches. Ask this question before installing a cool roof: Where will the reflected sunlight go? A bright, reflective roof could reflect light and heat into the higher windows of taller neighboring buildings. In sunny conditions, this could cause uncomfortable glare and unwanted heat for you or your neighbors. Excess heat caused by reflections increases air conditioning energy use, negating some of the energy saving benefits of the cool roof.” 159:

longevity of roof membranes. Reducing the extremes of temperature change will reduce the incidence of damage to membrane systems. Covering membranes with materials that reflect ultraviolet and infrared radiation will reduce damage caused by UV and heat degradation. White surfaces reflect more than half of the radiation that reaches them, while black surfaces absorb almost all. White or white coated roofing membranes, or white gravel cover would appear to be the best approach to control these problems where membranes must be left exposed to solar radiation.

982:, and has coated over 5 million square feet of NYC rooftops white. On Wednesday, September 25, 2013 Mayor Michael R Bloomberg declared it "NYC °CoolRoofs Day" in New York City with the coating of its 500th building and reducing the carbon footprint by over 2000 tons. Volunteers use paintbrushes and rollers to apply an acrylic, elastomeric coating to the roof membrane. A 2011 Columbia University study of roofs coated through the program found that white roofs showed an average temperature reduction of 43 degrees Fahrenheit when compared to black roofs. 163:(1,000 sq ft) white roof will offset 10 tons of carbon dioxide over its 20-year lifetime. In a real-world 2008 case study of large-scale cooling from increased reflectivity, it was found that the Province of Almeria, Southern Spain, has cooled 1.6 °C (2.9 °F) over a period of 20 years compared to surrounding regions, as a result of polythene-covered greenhouses being installed over a vast area that was previously open desert. In the summer the farmers whitewash these roofs to cool their plants down. 959:

consumption in the EU; to remove and simplify the procedures for cool roofs integration in construction and building's stock; to change the behaviour of decision-makers and stakeholders so to improve acceptability of the cool roofs; to disseminate and promote the development of innovative legislation, codes, permits and standards, including application procedures, construction and planning permits concerning cool roofs. The work will be developed in four axes, technical, market, policy and end-users.

365:(Pacific Northwest National Laboratory) in 2011. These guides were aimed at improvements to existing Retail and Office buildings which could improve their energy efficiency. Cool roofs were not recommended for all locations. “This measure is likely more cost-effective in the hot and humid climate zone, which has a long cooling season, than in the very cold climate zone, for example. For buildings located in warm climates, this measure is worth consideration.” 596:

have a lower impact the more insulation is used. The Secretary of Energy directed all U.S. Department of Energy (DOE) offices to install cool roofs, when life-cycle cost-effectiveness is demonstrated, when constructing new roofs, or when replacing old roofs at DOE facilities. Other Federal agencies were also encouraged to do the same."

318:, explored the relative effectiveness of some of the most common adaptation technologies aimed at reducing warming from urban expansion. Results of the study indicate that the performance of urban adaptation technologies can counteract this increase in temperature, but also varies seasonally and is geographically dependent. 517:

Administration, 2003 Commercial Buildings Energy Consumption Survey, heating accounts for 36% of commercial buildings' annual energy consumption, while air conditioning only accounts for 8% in United States. Energy calculators generally show a yearly net savings for dark-colored roof systems in cool climates.

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Under the LEED 2009 version, to receive Sustainable Sites Credit 7.2 Heat Island Effect-Roof, at least 75% of the surface of a roof must use materials having a solar reflective index (SRI) of at least 78. This criterion can also be met by installing a vegetated roof for at least 50% of the roof area,

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For low-slope roof applications, a roof product qualifying for the Energy Star label under its Roof Products Program must have an initial solar reflectivity of at least 0.65, and weathered reflectance of at least 0.50, in accordance with EPA testing procedures. Warranties for reflective roof products

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In addition to the white Thermoplastic PVC and TPO membranes used in many commercial cool roof applications, there is also research in the field of cool asphalt shingles. Asphalt shingles make up the majority of the North American residential roofing market, and consumer preferences for darker colors

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programs advocate the use of cool roofing to mitigate the urban heat island effect and the resulting poorer air quality (in the form of smog) the effect causes. By reflecting sunlight, light-colored roofs minimize the temperature rise and reduce cooling energy use and smog formation. A study by LBNL

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Green Globe uses performance benchmark criteria to evaluate a building's likely energy consumption, comparing the building design against data generated by the EPA's Target Finder, which reflects real building performance. Buildings may earn a rating of between one and four globes. This is an online

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announced a series of initiatives to more broadly implement cool roof technologies on DOE facilities and buildings across the country. As part of the new efforts, DOE will install a cool roof, whenever cost-effective over the lifetime of the roof, during construction of a new roof or the replacement

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Another method of evaluating coolness is the solar reflectance index (SRI), which incorporates both solar reflectance and emittance in a single value. SRI measures the roof's ability to reject solar heat, defined such that a standard black (reflectance 0.05, emittance 0.90) is 0 and a standard white

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has conducted several studies, beginning in 2002, which examined the elevated temperatures of wiring inside conduits at and above various color roof materials. The findings concluded that the temperatures above cool roofs were higher than those of a darker colored roof material. This illustrates the

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White thermoplastic membrane roofs (PVC and TPO) are inherently reflective, achieving some of the highest reflectance and emittance measurements of which roofing materials are capable. A roof made of white thermoplastic, for example, can reflect 80 percent or more of the sun's rays and emit at least

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When sunlight falls on a white roof much of it is reflected and passes back through the atmosphere into space. But when sunlight falls on a dark roof most of the light is absorbed and re-radiated as much longer wavelengths, which are absorbed by the atmosphere. (The gases in the atmosphere that most

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and specific "in-house" committees may add, subtract or edit the standard, based on an internal review process. Model Building Codes are voted on by members and "in-house" committees, but allow for comments and testimony from the general public during each and every code development cycle at Public

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ranked Cool Roofs as a 53 out of 100 (0 to 100 weighted average) for a cost-effective energy strategy. "Climate issues can affect cool roof performance. Cool roofs are more beneficial in warmer climates and may cause energy consumption for heating applications to rise in colder climates. Cool roofs

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Instruments measured weather conditions on the roof, temperatures inside the building and throughout the roof layers, and air conditioning and total building power consumption. Measurements were taken with the original black rubber roofing membrane and then after replacement with a white vinyl roof

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Cool Roof Rating Council (CRRC) has created a rating system for measuring and reporting the solar reflectance and thermal emittance of roofing products. This system has been put into an online directory of more than 850 roofing products and is available for energy service providers, building code

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Green roofs provide a thermal mass layer which helps reduce the flow of heat into a building. The solar reflectance of green roofs varies depending on the plant types (generally 0.3–0.5). Green roofs may not reflect as much as a cool roof but do have other benefits such as evapotranspiration which

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into the interaction between reflective pavements and buildings found that, unless the nearby buildings are fitted with reflective glass or other mitigation factors, solar radiation reflected off light-colored pavements can increase the temperature in nearby buildings, increasing air conditioning

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The highest SRI rating, and the coolest roofs, are stainless steel roofs, which are just several degrees above ambient under medium wind conditions. Their SRI's range from 100 to 115. Some are also hydrophobic so they stay very clean and maintain their original SRI even in polluted environments.

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significantly reduces the peaks of heat conduction transfer and roof-top surface temperature as well as the values of heat conduction transfer and roof-top surface temperature throughout diurnal profiles. Contrarily, the results also reveal that it does not influence the nocturnal profiles, as a

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Research and practical experience with the degradation of roofing membranes over a number of years have shown that heat from the sun is one of the most potent factors that affects durability. High temperatures and large variations, seasonally or daily, at the roofing level are detrimental to the

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Strengthening and Implementing the Global Response. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of

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An urban heat island occurs where the combination of heat-absorbing infrastructure such as dark asphalt parking lots and road pavement and expanses of black rooftops, coupled with sparse vegetation, raises air temperature by 1 to 3 °C (1.8 to 5.4 °F) higher than the temperature in the

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Though a full year of actual data was collected, due to aberrations in the data, one month of data was excluded along with several other days which didn't meet the parameters of the study. Only 36 continuous pre-retrofit days were used and only 28 non-continuous operating days were used for the

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Unlike other Energy Star-rated products, such as appliances, this rating system does not look at the entire roof assembly, but only the exterior surface. Consumers (i.e. building owners) may believe that the Energy Star label means their roof is energy-efficient; however, the testing is not as

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A perfect SRI is approximately 122, the value for a perfect mirror, which absorbs no sunlight and has very low emissivity. The only practical material which approaches this level is stainless steel with an SRI of 112. High-reflectivity, low-emissivity roofs maintain a temperature very close to

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Specifically, what works in California's Central Valley, such as cool roofs, does not necessarily provide the same benefits to other regions of the country, like Florida. Assessing consequences that extend beyond near surface temperatures, such as rainfall and energy demand, reveals important

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study looking at this issue for air-conditioned commercial buildings across the United States found that the summer cooling savings typically outweigh the winter heating penalty even in cold climates near the Canada–US border giving savings in both electricity and emissions. Without a proper

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The aim of the proposed action is to create and implement an Action Plan for the cool roofs in EU. The specific objectives are: to support policy development by transferring experience and improving understanding of the actual and potential contributions by cool roofs to heating and cooling

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In some climates where there are more heating days than cooling days, white reflective roofs may not be effective in terms of energy efficiency or savings because the savings on cooling energy use can be outweighed by heating penalties during winter. According to the U.S. Energy Information

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If all urban, flat roofs in warm climates were whitened, the resulting 10% increase in global reflectivity would offset the warming effect of 24 gigatonnes of greenhouse gas emissions, or equivalent to taking 300 million cars off the road for 20 years. This is because a 93-square-metre

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A 2012 study by researchers at Concordia University included variables similar to those used in the Stanford study (e.g., cloud responses) and estimated that worldwide deployment of cool roofs and pavements in cities would generate a global cooling effect equivalent to offsetting up to

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Solar reflective cars or cool cars reflect more sunlight than dark cars, reducing the amount of heat that is transmitted into the car's interior. Therefore, it helps decrease the need for air conditioning, fuel consumption, and emissions of greenhouse gases and urban air pollutants.

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When the sunlight strikes a dark rooftop, about 15% of it gets reflected back into the sky but most of its energy is absorbed into the roof system in the form of heat. Cool roofs reflect significantly more sunlight and absorb less heat than traditional dark-colored roofs.

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in order to provide industry-consensus roof savings for both residential and commercial buildings. It reports the net annual energy savings (cooling energy savings minus heating penalties) and thus is only applicable to the buildings with a heating and/or cooling system.

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White Roof Project is a US nationwide initiative that educates and empowers individuals to coat rooftops white. The program's outreach has helped complete white roof projects in more than 20 US states and five countries, engaged thousands in volunteer projects, and

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system is used in Canada and the United States. In the U.S., Green Globes is owned and operated by the Green Building Initiative (GBI). In Canada, the version for existing buildings is owned and operated by BOMA Canada under the brand name 'Go Green' (Visez vert).

90:, the IPCC 2018 report indicated that the potential for global temperature reduction was "small," yet was in high agreement over the recognition of temperature changes of 1-3 °C on a regional scale. Limited application of reflective surfaces can mitigate 553:

Another case study, conducted in 2009 and published in 2011, was completed by Ashley-McGraw Architects and CDH Energy Corp for Onondaga County Dept. of Corrections, in Jamesville, New York, evaluated energy performance of a green or vegetative roof, a dark

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CRRC's rating program allows manufacturers and sellers to appropriately label their roofing products according to specific CRRC measured properties. The program does not, however, specify minimum requirements for solar reflectance or thermal emittance.

970:) do not reflect heat as well as the truly "cool" color of white, especially as metallic surfaces fail to emit infrared back to the sky. European fashion trends are now using darker-colored aluminium roofing, to pursue consumer fashions. 790:(LEED) rating system is a voluntary, continuously evolving national standard for developing high performance sustainable buildings. LEED provides standards for choosing products in designing buildings, but does not certify products. 2932: 2081: 1612: 97:

Reflective surfaces can be used to change the albedo of agricultural and urban areas, noting that a 0.04-0.1 albedo change in urban and agricultural areas could potentially reduce global temperatures for overshooting 1.0 °C.

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An existing (or new) roof can be made reflective by applying a solar reflective coating to its surface. The reflectivity and emissivity ratings for over 500 reflective coatings can be found in the Cool Roofs Rating Council.

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A perfect roof would absorb no heat in the summer and lose no heat in the winter. To do this it would need a very high SRI to eliminate all radiative heat gains in summer and losses in winter. High SRI roofs act as a

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de Coninck, H., A. Revi, M. Babiker, P. Bertoldi, M. Buckeridge, A. Cartwright, W. Dong, J. Ford, S. Fuss, J.-C. Hourcade, D. Ley, R. Mechler, P. Newman, A. Revokatova, S. Schultz, L. Steg, and T. Sugiyama, 2018:

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and covered the building types of Small to Medium Office Buildings, Medium to Big Box Retail Buildings, Large Hospitals and K-12 School Buildings. In Climate Zones 4 and above the recommendation is to follow the

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release of heat to the sky takes place throughout the night. The release of heat from the building occurs due to the absence of solar radiation, which reduces the sky temperature and enables the sky to act as a

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Pisello, A.L.; Castaldo, V.L.; Pignatta, G.; Cotana, F.; Santamouris, M. (2016). "Experimental in-lab and in-field analysis of waterproof membranes for cool roof application and urban heat island mitigation".

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Cool roofs achieve cooling energy savings in hot summers but can increase heating energy load during cold winters. Therefore, the net energy saving of cool roofs varies depending on climate. However, a 2010

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cools the plants and the immediate area around the plants, aiding in lowering rooftop temperatures but increasing humidity, naturally. Moreover, some Green roofs need maintenance such as regular watering.

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ambient at all times preventing heat gains in hot climates and minimizing heat loss in cold climates. High emissivity roofs have much higher heat loss in cold climates for the same insulation values.

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showed that, if strategies to mitigate this effect, including cool roofs, were widely adopted, the Greater Toronto metropolitan area could save more than $ 11 million annually on energy costs.

525:, providing a thermos-bottle effect. High emissivity cool roofs carry a climate penalty due to winter radiative heat losses, which reflective bare metal roofs, such as stainless steel, do not. 78:

called the "cool roof". While cool roofs are mostly associated with white roofs, they come in a variety of colors and materials and are available for both commercial and residential buildings.

1604: 2928: 2070: 3191: 2564: 1537: 992: 2958: 1127:"Effect of Roof Tile Colour on Heat Conduction Transfer, Roof-Top Surface Temperature and Cooling Load in Modern Residential Buildings under the Tropical Climate of Malaysia" 105:(PDRC) being that they are both ground-based, yet PDRC focuses on "increasing the radiative heat emission from the Earth rather than merely decreasing its solar absorption." 354:

standard for roof reflectance, which does not require roofs to be reflective in these zones. In Climate Zones 4 and above, Cool Roofs are not a recommended Design Strategy.

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effect", they may actually increase global temperature. The study noted that it did not account for the reduction in greenhouse gas emissions that results from building

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must be equal in all material respects to warranties offered for comparable non-reflective roof products, either by a given company or relative to industry standards.

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and the U.S. Department of Energy designed to reduce greenhouse gas emissions and help businesses and consumers save money by making energy-efficient product choices.

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bodies, architects and specifiers, property owners and community planners. CRRC conducts random testing each year to ensure the credibility of its rating directory.

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to manufacture mirrors and polymer reflective films for potential widespread use on rooftops and in open spaces such as farmland. Trials have been undertaken in

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idea in which deflected solar radiation, when impeded by rooftop equipment, piping, or other materials will be subjected to the heat gain of the radiation.

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and vegetated roof in combination that meets this formula: (Area of Roof meeting Minimum SRI Roof/0.75) + (Area of vegetated roof/0.5) ≥ Total Roof Area.

2047: 1356:"Potential benefits of cool roofs on commercial buildings: conserving energy, saving money, and reducing emission of greenhouse gases and air pollutants" 2380: 1928: 407:, is the ability to reflect sunlight. It is expressed either as a decimal fraction or a percentage. A value of 0 indicates that the surface absorbs all 2522: 1957: 566:

surface. The reduction in solar absorption reduced solar gains in the summer but also increased heat losses during the heating season. Compared to the

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Levinson, Ronnen (2007-02-15). "Methods of creating solar-reflective nonwhite surfaces and their application to residential roofing materials".

3181: 2906: 1541: 257:" absorbs visible light, and emits light in the near-infrared range. It may be useful in construction materials to keep roofs and walls cool. 2676: 1446: 539: 446: 250: 2147: 3150: 1125:

Farhan, Syed Ahmad; Ismail, Fouad Ismail; Kiwan, Osamah; Shafiq, Nasir; Zain-Ahmed, Azni; Husna, Nadzhratul; Hamid, Afif Izwan Abd (2021).

1498:"Surface temperature cooling trends and negative radiative forcing due to land use change toward greenhouse farming in southeastern Spain" 2258: 471:

which are designed to reflect solar radiation may use modified mixes, reflective coatings, permeable pavements, and vegetated pavements.

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A series of Advanced Energy Retrofit Guides for “Practical Ways to Improve Energy Performance” were developed in cooperation with the

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H. Suehrcke; E. L. Peterson & N. Selby (2008). "Effect of roof solar reflectance on the building heat gain in a hot climate".

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Menon, Surabi; Ronnen Levinson; Marc Fischer; Dev Millstein; Nancy Brown; Francisco Salamanca; Igor Sednev; Art Rosenfeld (2011).

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roof. The measured results showed that the TPO and vegetative roof systems had much lower roof temperatures than the conventional

330: 3066: 2855: 2826: 1670: 3032: 71:), change of albedo at a larger scale (covering glaciers or deserts with reflective sheeting and changes in ocean albedo)." 2583: 2008: 1066: 978:

NYC °CoolRoofs is a New York City initiative to coat rooftops white with volunteers. The program began in 2009 as part of

442: 435: 175: 2929:"Southern California Edison's New Service Center in Wildomar Awarded Platinum Certification by National Building Council" 417:

is the ability to emit absorbed heat. It is also expressed either as a decimal fraction between 0 and 1, or a percentage.

3373: 3363: 315: 303: 2652: 3368: 3297: 2624: 2236: 1472: 798: 1106: 369: 3332: 3213: 3087: 2705: 2283: 1986: 967: 345:(United States Department of Energy) in 2011. These guides were aimed at achieving 50% Energy Savings toward a Net 203:

150 gigatonnes of carbon dioxide emissions – enough to take every car in the world off the road for 50 years.

2412: 179: 2617:"Measured energy savings and demand reduction from a reflective roof membrane on a large retail store in Austin" 2314: 260:

They have also developed fluorescent ruby red coatings which have reflective properties similar to white roofs.

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This project is co-financed by the European Union in the framework of the Intelligent Energy Europe Programme.

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Mirrors are being explored as a reflective surface to reflect solar radiation and cool temperatures. MEER is a

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maintenance program to keep the material clean, the energy savings of cool roofs can diminish over time due to

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Natural white gravel covering can be seen as an alternative option to obtain cool roofing and cool pavements.

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strongly absorb these long wavelengths have been termed "greenhouse gases"). Findings of a study conducted by

2450: 2387: 1920: 3266: 2565:"A nonprofit is using mirrors as a climate solution to a heating planet. Could MEER be in Arizona's future?" 2514: 1949: 438:

which estimates cooling and heating savings for low-slope roof applications with white and black surfaces.

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Levinson, Ronnen; Pan, Heng; Ban-Weiss, George; Rosado, Pablo; Paolini, Riccardo; Akbari, Hashem (2011).

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Georgescu, Matei; Morefield, Philip E.; Bierwagen, Britta G.; Weaver, Christopher P. (5 February 2014).

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membrane, the TPO roof had 30% higher heating losses and the vegetative roof had 23% higher losses.

2796: 1810: 1330: 1031: 963: 314:'s School of Geographical Sciences and Urban Planning and a senior sustainability scientist in the 292: 284: 196: 2680: 3186: 2139: 1740: 1377: 1302: 1198: 1076: 1004: 770: 484: 3158: 2040:"You Know The Roof Your Wife Painted White Last Summer? Well, She Needs To Paint It Black Again" 2262: 2210: 1442: 414: 288: 287:

suggested that although reflective roofs decrease temperatures in buildings and mitigate the "

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Savings of up to 15% of the annual air-conditioning energy use for a single-story building

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The Roof Savings Calculator (RSC) is a tool developed by the U.S. Department of Energy's

3290:"Energy impacts of heat island reduction strategies in the Greater Toronto Area, Canada" 2472: 2186: 1605:"Painting roofs white is as green as taking cars off the roads for 50 years, says study" 1579: 1513: 1290: 141:, as well as a significant offsetting of the warming impact of greenhouse gas emissions. 123:

Cool roofs, in hot climates, can offer both immediate and long-term benefits including:

3358: 2205: 2170: 1588: 1563: 1081: 1013: 87: 1412: 329:(American Society of Heating, Refrigerating and Air-Conditioning Engineers), AIA (The 3352: 2849: 2818: 1381: 1202: 1158: 1036: 794: 492: 468: 254: 1862:"World's 1st artificially-made pigment Egyptian blue, can help produce solar energy" 1771:"Experimental analysis of natural gravel covering as cool roofing and cool pavement" 1744: 1662: 1306: 2488: 3247:. New York, NY: Applied Climatology: Principles & Practices. pp. 273–287. 3003: 1648: 310:

In 2014, a team of researchers, led by Matei Georgescu, an assistant professor in

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described this method as "whitening roofs, changes in land use management (e.g.,

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Cool color parking lots are parking lots made with a reflective layer of paint.

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Residential Compliance Manual For California's 2005 Energy Efficiency Standards

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Campra, Pablo; Monica Garcia; Yolanda Canton; Alicia Palacios-Orueta (2008).

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Limited application of reflective surfaces can mitigate urban heat pollution.

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There are two properties that are used to measure the effects of cool roofs:

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A series of Advanced Energy Design Guides were developed in cooperation with

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Examples of LEED-certified buildings with white reflective roofs are below.

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that promotes the transfer of heat from the building to the sky to achieve

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Berdahl, Paul; Akbari, Hashem; Jacobs, Jeffry; Klink, Frank (April 2008).

2854:. Washington, DC: United States Green Building Council, Inc. p. 20. 1522: 1497: 1108:

climate change, sustainable development, and efforts to eradicate poverty

183: 52: 3151:"Op-Ed: White Roofs Are the White Knight We Need to Slay Climate Change" 2171:"Urban adaptation can roll back warming of emerging megapolitan regions" 1979: 168: 16: 2677:"DOE Takes Steps to Implement Cool Roofs across the Federal Government" 1143: 1126: 253:

have determined that a pigment used by the ancient Egyptians known as "

218: 2584:"Table E1A. Major Fuel Consumption by End Use for All Buildings, 2003" 1787: 1770: 993:

sponsored the coating of hundreds of nonprofit and low-income rooftops

3221: 979: 811: 500: 404: 384: 377: 358: 342: 326: 152: 44: 21: 2140:"Research reveals effectiveness of urban heat-reducing technologies" 1396: 1275:"Global cooling: increasing world-wide urban albedos to offset CO2" 2851:

LEED 2009 for New Construction and Major Renovations Rating System

2442: 2420: 802: 496: 338: 334: 1769:

Pisello, A.L.; Pignatta, G.; Castaldo, V.L.; Cotana, F. (2014).

567: 563: 555: 362: 75: 3017: 1564:"The long-term effect of increasing the albedo of urban areas" 1471:. Sacramento, CA: California Energy Commission. Archived from 1273:

Akbari, Hashem; Menon, Surabi; Rosenfeld, Arthur (June 2009).

924:

Salt Lake City Olympic Winter Games 2002 Organizing Committee

60: 3258: 851:

Donald Bren School of Environmental Science & Management

3182:"So Cool! La MaMa, Theater for the New City Get White Roofs" 2788: 1802: 620:

Certification requirements for different cool roof programs

74:

The most well-known type of reflective surface is a type of

411:, and a value of 1 (or 100%) represents total reflectivity. 2679:. United States Department of Energy. 2010. Archived from 2760:"All Certified Products - ENERGY STAR Qualified Products" 221:

roof only reflects between 6 and 26% of solar radiation.

491:

and further application opportunities are developing in

182:

in 2021, which is based on the hot and humid climate of

2443:"Roof Savings Calculator (RSC) - DOE ORNL LBNL CEC EPA" 2413:"Roof Savings Calculator (RSC) - DOE ORNL LBNL CEC EPA" 2343: 2341: 2107:"Effect of reflective pavements on building energy use" 806:

Review hearings, generally held multiple times a year.

1320:

United States Environmental Protection Agency (2011).

618: 2623:. Lawrence Berkeley National Laboratory. LBNL-47149. 1562:

Akbari, Hashem; H Damon Matthews; Donny Seto (2012).

1323:

Reducing Urban Heat Islands: Compendium of Strategies

935:

Premier Automotive Group North American Headquarters

337:(Illuminating Engineering Society of North America), 217:

70% of the solar radiation that the roof absorbs. An

3323:, Global Cool Cities Alliance. Retrieved 2023-10-10. 1397:"Long-term performance of high-albedo roof coatings" 1120: 1118: 1116: 546:

with the same insulation and HVAC systems in place.

1177:"Tackling Climate Change through Radiative Cooling" 882:Travaux Public et Services Gouvernementaux Canada 3120:"Bright Is The New Black: New York Roofs Go Cool" 2754: 2752: 2733:. United States Environmental Protection Agency. 2610: 2608: 1950:"Are Ruby Red Crystals the Secret to Cool Roofs?" 907:National Geographic Society Headquarters Complex 2105:Yaghoobian, Neda; Kleissl, Jan (December 2012). 1395:Bretz, Sarah E.; Akbari, Hashem (January 1997). 3149:Juan Carlos Piñeiro Escoriaza (20 March 2013). 2903:"USGBC - Southern California Edison - Wildomar" 2646:"ashley%20roof%20final%20report-Oct%202011.pdf" 2175:Proceedings of the National Academy of Sciences 1354:Levinson, Ronnen; Akbari, Hashem (March 2010). 101:The reflective surfaces approach is similar to 3245:Urban Climates and Global Environmental Change 2591:Commercial Buildings Energy Consumption Survey 1837:Lawrence Berkeley Laboratory Heat Island Group 63:, reducing heat transfer to the surface). The 2700: 2698: 788:Leadership in Energy and Environmental Design 8: 2615:Konopacki, Steven J.; Hashem Akbari (2001). 1538:"Cool_Roofs_Science_at_Theater_Berkeley.ppt" 1234: 1232: 3243:Oke, TR. Thompson, R.D.; Perry, A. (eds.). 3063:"Cool Roofs Planned Across CUNY's Rooftops" 604:Energy Star is a joint program of the U.S. 422:(reflectance 0.80, emittance 0.90) is 100. 341:(United States Green Building Council) and 3033:"White Trumps Black in Urban Cool Contest" 1439:Roofs: Design, Application and Maintenance 1248:. US. Department of Energy. Archived from 3296:. Lawrence Berkeley National Laboratory. 3288:Konopacki, Steven; Hashem Akbari (2001). 2993: 2204: 2194: 2122: 1786: 1669:. Lawrence Berkeley National Laboratory. 1587: 1521: 1371: 1192: 1142: 361:(United States Department of Energy) and 2593:. U.S. Energy Information Administration 2545:"Cool Pavements Research and Technology" 854:University of California, Santa Barbara 819: 441:This tool was the collaboration of both 15: 2957:. EU Cool Roofs Council. Archived from 1092: 3088:"NASA Technical Reports Server (NTRS)" 2315:"Travis_Lindsey_Presentation_2011.pdf" 1980:"Cool Roofs, Cool Cities, Cool Planet" 1891:"Scientists give solar PV a paint job" 1725:Solar Energy Materials and Solar Cells 1694:Solar Energy Materials and Solar Cells 1615:from the original on 13 September 2017 1157:Sen, Sushobhan, and Lev Khazanovich. " 186:, suggest that the selection of white 3321:Cool Roofs and Cool Pavements Toolkit 2515:"Parking Lot Science: Is Black Best?" 1833:"Egyptian Blue for Energy Efficiency" 1673:from the original on 15 November 2016 1462:California Energy Commission (2005). 951:Cool Roofs Europe and other countries 540:Lawrence Berkeley National Laboratory 447:Lawrence Berkeley National Laboratory 251:Lawrence Berkeley National Laboratory 7: 3130:from the original on 9 December 2013 2848:U.S. Green Building Council (2009). 2737:from the original on 2 November 2011 2731:"Roof Products Key Product Criteria" 2543:Levine, Kendra (September 1, 2011). 1989:from the original on 7 December 2011 1100: 1098: 1096: 2935:from the original on 15 August 2016 2877:"Voluntary Green Building Programs" 2799:from the original on April 20, 2016 2582:Energy Information Administration. 2144:ASU Now: Access, Excellence, Impact 1813:from the original on April 20, 2016 1242:Guidelines for Selecting Cool Roofs 300:University of California, San Diego 3043:from the original on 11 April 2015 3031:Foster, Joanna M. (9 March 2012). 2909:from the original on 6 August 2016 2495:from the original on 21 April 2012 2284:"technical_report: PNNL-20814.pdf" 1215:U.S. Department of Energy (2010). 865:Frito-Lay Jim Rich Service Center 786:The U.S. Green Building Council's 593:United States Department of Energy 585:United States Department of Energy 579:Across the U.S. federal government 316:Global Institute of Sustainability 14: 3194:from the original on May 29, 2016 2955:"Market challenges on cool roofs" 1062:Passive daytime radiative cooling 588:of an old one at a DOE facility. 403:Solar reflectance, also known as 103:passive daytime radiative cooling 2879:. VinylRoofs.org. Archived from 1239:Urban, Bryan; Kurt Roth (2011). 331:American Institute of Architects 33:ground-based albedo modification 3300:from the original on 2015-04-02 3269:from the original on 2015-08-14 3118:Lynch, Patrick (7 March 2012). 3100:from the original on 2020-09-30 2858:from the original on 2011-12-18 2829:from the original on 2014-07-04 2770:from the original on 2014-02-27 2712:from the original on 2014-02-27 2627:from the original on 2014-04-16 2525:from the original on 2013-10-04 2453:from the original on 2014-04-03 2327:from the original on 2016-03-04 2296:from the original on 2013-11-26 2229:"Advanced Energy Design Guides" 2150:from the original on 2014-11-12 2087:from the original on 2016-05-13 2071:"Cool Roofs and Global Cooling" 2021:from the original on 2012-01-11 1960:from the original on 2018-10-15 1931:from the original on 2018-10-14 1901:from the original on 2018-10-14 1872:from the original on 2018-10-12 1843:from the original on 2018-10-14 1751:from the original on 2020-06-29 1603:Connor, Steve (13 April 2012). 1502:Journal of Geophysical Research 1419:from the original on 2021-11-22 606:Environmental Protection Agency 283:A 2011 study by researchers at 2489:10.1016/j.apenergy.2011.05.006 370:Copper Development Association 1: 3004:10.1016/j.enbuild.2008.06.015 2381:"Cool Roof Q & A (draft)" 2009:"HeatIsland+WhiteRfs0911.pdf" 1649:10.1016/j.enbuild.2015.05.026 1413:10.1016/S0378-7788(96)01005-5 1067:Passive solar building design 634:Min. solar reflectance index 538:In a 2001 federal study, the 443:Oak Ridge National Laboratory 436:Oak Ridge National Laboratory 176:Universiti Teknologi PETRONAS 3214:"About - White Roof Project" 1737:10.1016/j.solmat.2007.10.011 1706:10.1016/j.solmat.2006.06.062 1589:10.1088/1748-9326/7/2/024004 1441:. Polyscience Publications. 966:(silvery) sheeting (usually 910:National Geographic Society 558:roof and a white reflective 304:Jacobs School of Engineering 109:Types of reflective surfaces 47:(the ability to reflect the 43:method of enhancing Earth's 2259:"PNNL: Publication Details" 2124:10.1016/j.uclim.2012.09.002 1194:10.1016/j.joule.2019.07.010 840:Southern California Edison 799:International Building Code 3392: 3333:Carnegie Mellon University 2789:"Cool Roof Rating Council" 2563:Dana, Joe (20 June 2022). 1919:Chao, Julie (2016-09-21). 1803:"Cool Roof Rating Council" 1002: 857:Santa Barbara, California 307:demands and energy usage. 267: 137:Reduced air pollution and 41:solar radiation management 2379:Levinson, Ronnen (2009). 2138:Skip Derra (2014-02-10). 1978:Levinson, Ronnen (2010). 1373:10.1007/s12053-008-9038-2 1299:10.1007/s10584-008-9515-9 1010:surrounding countryside. 720: 691: 638: 624: 180:Universiti Teknologi MARA 155:degradation and soiling. 24:of several types of roofs 3335:, School of Architecture 1925:Berkeley Lab News Center 1437:Maxwell C Baker (1980). 999:Urban heat island effect 893:Seattle Central Library 837:Wildomar Service Center 752:Cool Roof Rating Council 633: 630: 627: 312:Arizona State University 139:greenhouse gas emissions 2196:10.1073/pnas.1322280111 1175:Munday, Jeremy (2019). 962:In tropical Australia, 628:Min. solar reflectance 430:Roof Savings Calculator 298:Also, 2012 research at 130:Help in mitigating the 86:As a method to address 3328:"Smart Surfaces Guide" 1165:12, no. 1 (2021): 1-8. 879:Edifice Multifunction 801:, only members of the 550:post-retrofit period. 25: 3180:REBECCA PRUSINOWSKI. 1163:Nature Communications 927:Salt Lake City, Utah 843:Wildomar, California 810:or installing a high 591:In October 2013, the 483:proposing the use of 19: 3259:"Heat Island Effect" 2982:Energy and Buildings 1868:. October 11, 2018. 1637:Energy and Buildings 1523:10.1029/2008JD009912 1401:Energy and Buildings 1217:Cool roof fact sheet 1110:. In Press. Pg. 348. 1072:Passive solar design 871:Rochester, New York 574:Promotional programs 347:zero-energy building 3374:Climate engineering 3364:Low-energy building 2349:"coolroofguide.pdf" 2187:2014PNAS..111.2909G 2050:on October 23, 2014 1983:(PowerPoint Slides) 1897:. October 9, 2018. 1839:. October 9, 2018. 1580:2012ERL.....7b4004A 1514:2008JGRD..11318109C 1291:2009ClCh...94..275A 1032:Building insulation 941:Irvine, California 938:Ford Motor Company 621: 293:energy conservation 285:Stanford University 249:Researchers at the 197:thermal equilibrium 59:wavelengths of the 29:Reflective surfaces 3369:Solar architecture 3218:White Roof Project 3187:The New York Times 3037:The New York Times 2819:"Code Development" 2764:www.energystar.gov 2550:2017-02-20 at the 2239:on August 10, 2016 2078:heatisland.lbl.gov 1568:Environ. Res. Lett 1222:2017-02-10 at the 1144:10.3390/su13094665 1077:Thermal insulation 1005:Urban heat islands 986:White Roof Project 921:Utah Olympic Oval 619: 583:In July 2010, the 507:Climatic variables 485:recycled materials 245:Blue and red roofs 26: 3224:on April 10, 2015 2483:(12): 4343–4357. 1788:10.3390/su6084706 1667:Heat Island Group 1448:978-0-921317-03-6 1360:Energy Efficiency 948: 947: 913:Washington, D.C. 885:Montreal, Quebec 749: 748: 415:Thermal emittance 383:According to the 376:According to the 289:urban heat island 169:Syed Ahmad Farhan 148:energy efficiency 132:urban heat island 92:urban heat island 3381: 3345: 3343: 3342: 3309: 3308: 3306: 3305: 3285: 3279: 3278: 3276: 3274: 3255: 3249: 3248: 3240: 3234: 3233: 3231: 3229: 3220:. Archived from 3210: 3204: 3203: 3201: 3199: 3177: 3171: 3170: 3168: 3166: 3157:. Archived from 3146: 3140: 3139: 3137: 3135: 3115: 3109: 3108: 3106: 3105: 3099: 3092: 3084: 3078: 3077: 3075: 3074: 3065:. Archived from 3059: 3053: 3052: 3050: 3048: 3028: 3022: 3021: 3018:"NYC °CoolRoofs" 3014: 3008: 3007: 2997: 2977: 2971: 2970: 2968: 2966: 2961:on 23 April 2012 2951: 2945: 2944: 2942: 2940: 2925: 2919: 2918: 2916: 2914: 2899: 2893: 2892: 2890: 2888: 2883:on 21 March 2012 2873: 2867: 2866: 2864: 2863: 2845: 2839: 2838: 2836: 2834: 2815: 2809: 2808: 2806: 2804: 2785: 2779: 2778: 2776: 2775: 2756: 2747: 2746: 2744: 2742: 2727: 2721: 2720: 2718: 2717: 2702: 2693: 2692: 2690: 2688: 2673: 2667: 2666: 2664: 2663: 2657: 2651:. Archived from 2650: 2642: 2636: 2635: 2633: 2632: 2612: 2603: 2602: 2600: 2598: 2588: 2579: 2573: 2572: 2560: 2554: 2541: 2535: 2534: 2532: 2530: 2511: 2505: 2504: 2502: 2500: 2468: 2462: 2461: 2459: 2458: 2439: 2433: 2432: 2430: 2428: 2419:. Archived from 2409: 2403: 2402: 2400: 2398: 2393:on 21 April 2012 2392: 2386:. Archived from 2385: 2376: 2370: 2369: 2367: 2366: 2360: 2354:. 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Archived from 1328: 1317: 1311: 1310: 1285:(3–4): 275–286. 1270: 1264: 1263: 1261: 1260: 1254: 1247: 1236: 1227: 1213: 1207: 1206: 1196: 1187:(9): 2057–2060. 1172: 1166: 1155: 1149: 1148: 1146: 1122: 1111: 1102: 1047:Insulative paint 896:City of Seattle 868:Frito-Lay, Inc. 820: 622: 212:White cool roofs 3391: 3390: 3384: 3383: 3382: 3380: 3379: 3378: 3349: 3348: 3340: 3338: 3326: 3317: 3312: 3303: 3301: 3287: 3286: 3282: 3272: 3270: 3257: 3256: 3252: 3242: 3241: 3237: 3227: 3225: 3212: 3211: 3207: 3197: 3195: 3179: 3178: 3174: 3164: 3162: 3148: 3147: 3143: 3133: 3131: 3117: 3116: 3112: 3103: 3101: 3097: 3090: 3086: 3085: 3081: 3072: 3070: 3061: 3060: 3056: 3046: 3044: 3030: 3029: 3025: 3016: 3015: 3011: 2995:10.1.1.659.4287 2988:(12): 2224–35. 2979: 2978: 2974: 2964: 2962: 2953: 2952: 2948: 2938: 2936: 2927: 2926: 2922: 2912: 2910: 2901: 2900: 2896: 2886: 2884: 2875: 2874: 2870: 2861: 2859: 2847: 2846: 2842: 2832: 2830: 2817: 2816: 2812: 2802: 2800: 2787: 2786: 2782: 2773: 2771: 2758: 2757: 2750: 2740: 2738: 2729: 2728: 2724: 2715: 2713: 2704: 2703: 2696: 2686: 2684: 2683:on 3 March 2016 2675: 2674: 2670: 2661: 2659: 2655: 2648: 2644: 2643: 2639: 2630: 2628: 2614: 2613: 2606: 2596: 2594: 2586: 2581: 2580: 2576: 2562: 2561: 2557: 2552:Wayback Machine 2542: 2538: 2528: 2526: 2513: 2512: 2508: 2498: 2496: 2470: 2469: 2465: 2456: 2454: 2441: 2440: 2436: 2426: 2424: 2423:on June 1, 2013 2411: 2410: 2406: 2396: 2394: 2390: 2383: 2378: 2377: 2373: 2364: 2362: 2358: 2351: 2347: 2346: 2339: 2330: 2328: 2324: 2317: 2313: 2312: 2308: 2299: 2297: 2293: 2286: 2282: 2281: 2277: 2268: 2266: 2257: 2256: 2252: 2242: 2240: 2227: 2226: 2222: 2168: 2167: 2163: 2153: 2151: 2137: 2136: 2132: 2104: 2103: 2099: 2090: 2088: 2084: 2073: 2068: 2067: 2063: 2053: 2051: 2038: 2037: 2033: 2024: 2022: 2018: 2011: 2007: 2006: 2002: 1992: 1990: 1982: 1977: 1976: 1972: 1963: 1961: 1948: 1947: 1943: 1934: 1932: 1918: 1917: 1913: 1904: 1902: 1895:PV magazine USA 1889: 1888: 1884: 1875: 1873: 1860: 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3385: 3377: 3376: 3371: 3366: 3361: 3351: 3350: 3347: 3346: 3324: 3316: 3315:External links 3313: 3311: 3310: 3280: 3265:. 2014-02-28. 3250: 3235: 3205: 3172: 3141: 3110: 3079: 3054: 3023: 3009: 2972: 2946: 2920: 2894: 2868: 2840: 2825:. 2015-01-02. 2810: 2780: 2748: 2722: 2694: 2668: 2637: 2604: 2574: 2555: 2536: 2521:. 2012-09-13. 2506: 2477:Applied Energy 2463: 2434: 2404: 2371: 2337: 2306: 2275: 2250: 2220: 2161: 2130: 2097: 2061: 2031: 2000: 1970: 1956:. 2016-09-28. 1941: 1911: 1882: 1853: 1824: 1794: 1775:Sustainability 1761: 1731:(4): 482–489. 1711: 1700:(4): 304–314. 1684: 1654: 1626: 1595: 1574:(2): 159–167. 1554: 1529: 1488: 1454: 1447: 1429: 1407:(2): 159–167. 1387: 1346: 1312: 1265: 1228: 1208: 1167: 1150: 1131:Sustainability 1112: 1091: 1089: 1086: 1085: 1084: 1082:Weatherization 1079: 1074: 1069: 1064: 1059: 1054: 1049: 1044: 1039: 1034: 1029: 1022: 1019: 1014:Green building 1003:Main article: 1000: 997: 987: 984: 975: 974:NYC °CoolRoofs 972: 952: 949: 946: 945: 942: 939: 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