At peak temperatures during summer months, the surface of a black roof can easily reach 170 degrees. The heat is transferred into the building below via conduction and causes the building's air conditioning units to work harder to maintain interior temperatures, thereby inflating energy bills.
Energy bills can be reduced up to 50% by utilizing ENERGY STAR-qualified roof coatings, which can reduce the amount of air conditioning needed in buildings. The program outlines standards for solar reflectance, three-year maintenance, and emissivity, which is a material’s ability to release absorbed heat.
Elastomeric coatings are almost always white or light-colored so as to reflect sunlight, rather than absorb it like black or darker colors would. Reflecting sunlight can lower the temperature of the roof surface up to 100 degrees.
Cool roofs can have a particularly favorable impact in urban areas. In cities, the combination of tightly packed buildings and few green spaces can contribute to a phenomenon known as an Urban Heat Island. The roofs of the buildings, which are often dark-colored, absorb sunlight and raise ambient temperatures well above what is observed in surrounding suburban and undeveloped areas. The abnormally high temperatures cause the building's air conditioning units to run more often and work harder, resulting in inflated energy bills. The installation of Cool Roofs will cause much of the previously absorbed sunlight to be reflected, thereby lowering ambient temperatures, air conditioner workloads, and energy bills.
The properties and performance of protective coatings can vary greatly, so it's important to consult established guidelines that outline the standards by which to compare coating products. If a coating has been tested to said standards and obtained approval by an authorized organization like the American Society for Testing and Materials (ASTM), proof of approval will be evident on a coating's packaging or labeling.