A roof is a building's first line of defense in controlling energy consumption. A solar reflective coating is a roof surface coating that lowers the surface temperatures of the roof dramatically, resulting in greater comfort inside the building and less demand on air conditioning equipment, resulting in lower energy costs. These solar reflective coatings are typically a white roof coating consisting of a polymeric binder blended with pigments and other additives or silver containing asphalt, pigment flakes and pure aluminum resulting in a silver reflective coating. Solar reflecting coatings provide two main benefits: 1) protection of roof membranes, for longer roof life cycles; and 2) reflectivity of solar radiation (amount of solar energy that is reflected away from a surface), for lowering of air conditioning costs.
White roofs reflect the sun’s heat and black roofs soak it in.
That’s the key advantage offered by a white solar reflective roof surface. Testing conducted on a sunny day at 100°F ambient temperature shows that the surface temperature of a roof topped with a black membrane can reach 180°F while a gravel roof can be as hot as 145°F. A roof with a solar reflective coating will reflect the sun’s heat, staying significantly cooler at 90°F, contributing to a cooler indoor environment and reducing peak cooling demand up to 15 percent. As "green" building standards (such as California’s Title 24 requirements) become more prevalent, products that contribute to reduced environmental impact become more necessary.
Solar reflectance isn't the only property to look for in a roofing material. It should also have a high infrared emittance (the amount of absorbed heat energy that is radiated from a surface) to help the roof shed heat by re-radiation.
Solar reflective coatings can either be applied to the roofing membrane at the factory, such as CertainTeed’s CoolStar line of solar reflective roof membranes, or after the roof is applied to the building, such as CertainTeed’s FlintCoat –A 300
, FlintCoat –A Plus
and FlintCoat –W
. The advantage of a factory pre-coated roof surface is that it allows for a hassle-free, one-step field application. Once the roof system is applied, the job is complete. This one-step installation helps reduce labor costs because there are no costly time delays for application of multiple coats. Applying the roof solar reflective coatings after the roof system is complete is typically accomplished with the use of a roller, brush or with conventional airless spray equipment and the coating dries to a tough, flexible elastic film.
Look for solar reflective membranes and coating products that meet ENERGY STAR® requirements, are rated by the Cool Roof Rating Council, and contribute credits under the U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED®) Green Building Rating System™.