The idea behind cool roofing is the same as the reasons people living in hot climates wear light colored clothing. Here in the desert southwest, wearing light-colored or white clothing helps keep you cool. Its because light colors reflect heat and sunlight, whereas dark colors absorb them. Homes are similar to people. If your roof is dark colored, your home will be hotter than if it had a light-colored roof. During the hot summer months we experience here in the Phoenix area, a darker colored roof can reach temperatures as high as 150 to 190 degrees at their peak. In contrast, a cool roofing system will peak at around 100 to 120 degrees.
They are made of materials that reflect the energy and heat from the sun away from the surface of your roof. The materials for homes with low-slope roofs are typically bright white, however, there are other colors that are being made for more sloped roof applications. Cool roofing is highly emissive, which allows it to emit infrared energy away from the roof. Bare metals and metallic coatings usually don’t have low emissive abilities, which is one of the reasons they aren’t thought of as cool roofing materials.
Initial costs for a cool roof are similar to traditional roofing materials. Some cool roofing materials cost less than traditional materials and some cost more. Cool protective coatings can be applied every 10 to 15 years, which can reduce, or eliminate, the need for expensive roof tear-offs and replacements. If you add these roof repair or replacement savings with an average 20 percent savings on utility costs, it makes a cool roof a money saver over the life of your property. You can also get rebates in some communities, in addition to energy and lifespan savings, from local utility companies for installing cool roofing on your home.
There are 2 two types of materials for low-slope roofing systems on homes – single-ply materials and reflective coatings. Single-ply materials are made of large sheets of pre-constructed roofing fastened together over the old roof and sealed at the seams. Reflective coatings are installed or applied over an existing clean, leak-free roof surface using rollers, sprayers, or brushes.
There are other materials available for sloped roofs in clay or concrete tiles. They stay cool by using certain pigments that reflect the sun’s infrared heat. There aren’t asphalt shingles or pre-coated metal roofing materials available in cool versions right now.
You can visit the ENERGY STAR® Website for a comprehensive list of cool roofing system products and manufacturers at www.energystar.gov.