in different climates, outdoor exposure is conducted for three years in each of three different climates: 1) Miami, Florida: hot and humid; 2) Phoenix, Arizona: hot and dry; and 3) Cleveland, Ohio: cold/temperate. Results from the three sites are averaged to provide a ‘U.S.’ value.
Building Owners and the Environment Keep Their Cool with Cool Roofs
When properly installed and maintained, cool roofs can provide a variety of benefits that contribute to the community’s health, the building occupants, and the owner’s wallet. Building occupants can experience improved comfort as compared to a conventional dark roof, as the building’s interior is subject to less thermal flux and stays cooler during warm seasons. Reduced indoor temperatures lead to energy savings from reduced cooling energy loads. Cool roofs are distinguished among energy conservation measures because of their ability to help mitigate the urban heat island effect, a phenomenon characterized by a measured increase in the ambient air temperature in cities over their surrounding rural areas. This effect is due to roofs and non-reflective surfaces that absorb and trap heat, gradually warming the ambient air temperature and causing cities to be up to 8°F warmer than their surrounding areas. Cool roofs help improve urban conditions by contributing to cooler ambient temperatures by immediately reflecting solar radiation back into the atmosphere before it can degrade to heat, as well as reemitting a portion of infrared light. Reduced air conditioning loads can also improve grid stability, increasing peak energy savings, reducing the risk of brown outs or black outs, and decreasing pollution production. Lower ambient air temperatures also contribute to improved air quality by combating the formation of ground-level ozone, a pollutant which forms more readily in hot environments. This effect is magnified by the reduction of pollutants and greenhouse gas emissions from power plants by reducing electricity demands for air conditioning.
Product Types: Cool Roofs Need Not be White
Cool roofing products are available in a variety of colors and materials, including but not limited to: built-up roofing capsheets, foam roof systems, metal panels, field-applied coatings, tile, and single-ply membranes. While white roofs tend to offer the highest solar reflectances and thermal emittances, other colors and even patterns can perform as well as some white options. Ultimately, roofing materials should be carefully selected based on the slope of the roof, energy savings goals, the project location and climate, local code requirement or green building credits, and aesthetic preferences. A useful resource to help locate cool roofs by product type is the CRRC Rated Products Directory.
Green Roofs
Green roofs, also known as vegetated roofs, use plants as roof covering and are distinct from cool roofs. While typically not highly reflective (a key feature of a “cool” roof), green roofs can stay cooler than a traditional non-cool roof through
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Roof Tile & Slate Supply Experts
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