The hotter the roof, the more energy it takes to cool the building beneath it. So, in 1999, the U.S. Environmental Protection Agency's Energy Star program began rating roofing materials for energy efficiency. Traditionally, asphalt shingles have been among the hottest roofing materials available, but manufacturers have been finding ways to make them more reflective and reduce the amount of heat they absorb. Many of them have earned an Energy Star rating.
Dark Roofs Equal Hot Roofs
In general, dark colors tend to absorb more heat, and on roofs, that heat is transferred to the building. Studies by the Heat Island Group and the Florida Solar Energy Center have shown that buildings with dark roofs required up to 40 percent more energy to cool than buildings with light-colored or reflective roofs (see References 4 and 5). Even among the qualified Energy Star shingles, the lighter ones tend to carry a better Energy Star rating than the darker ones.
Benefits of Energy Star
Energy Star-qualified shingles come in a variety of colors, including dark colors, even dark browns and grays. They are designed with special granules that make them more reflective than standard asphalt, so they absorb less heat. Surface temperatures can be as much as 100 degrees Fahrenheit lower on roofs with qualified shingles. That can translate into a 10 to 15 percent reduction in the amount of energy needed to cool the building during peak cooling periods. (See Reference 2)
Finding Roof Shingles and Ratings
The Cool Roof Rating Council certifies roof products for the Energy Star program. Its website offers a comprehensive list of roof materials and manufacturers. The list includes an Energy Star rating for each type of roof material. As of late 2010, three manufacturers carried qualified Energy Star shingles. Most of these are available at home stores and building supply houses.
Don't Forget the Tax Breaks
The U.S. federal government offers tax credits and other incentives for energy-efficient home products. The incentives change from year to year, so it is important to check with a tax accountant. In 2011, the tax credit for installing a qualified Energy Star roof on a principal residence equals 10 percent of the cost of the roof up to $500. Many states also offer grants, tax exemptions or credits and other incentives for using green products. (See References 3)
- U.S. Environmental Protection Agency: Heat Island Effect
- Energy Star: Roof Products
- Energy Star: 2011 Federal Tax Credits for Consumer Energy Efficiency
- Heat Island Group: Cool Roofs
- Florida Solar Energy Center: Comparative Evaluation of the Impact of Roofing Systems on Residential Cooling Energy Demand in Florida
A former science writer for the Smithsonian Institution, Kimbra Cutlip is a freelance writer and children's book author whose articles have appeared in numerous national publications. A certified group fitness instructor and emergency medical technician, Cutlip co-owns a remodeling company specializing in energy-efficient sustainable building and solar hot water systems. She holds Bachelor of Arts degrees in magazine journalism and anthropology.
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