Your roofing material can make a
difference in energy costs.

Lower Energy Costs

Anyone who's worn a black T-shirt in the blazing sun or sat on a dark vinyl car seat during the summer knows that darker colors absorb more heat than lighter hues. In a recent study, the Florida Power & Light Co. proved the same principle applies to roofs and directly affects homeowners' energy budgets. In tests comparing various residential roofing materials, the company found that the lighter the roof color, the lower the price of cooling the home.

During the four-month study of six roofing materials -- dark gray shingles, white shingles, white flat cement tile, white S-shape cement tile, terra-cotta S-shape "Spanish" tile, and white metal -- the dark gray roofs reflected only 8 percent of the sun's heat. On the other hand, the white metal roof reflected 66 percent, the S-shape cement tiles reflected 74 percent, and the flat cement tiles reflected 77 percent of the sun's energy. White shingle and terra-cotta tile roofs fell in the middle, reflecting 25 and 34 percent, respectively. Overall, though, the white, galvanized metal roof saved the most energy because it cooled down the most at night.

The study focused on identical, side-by-side residences built by Habitat for Humanity, a nonprofit organization that helps needy families build their own affordable housing. Each home's thermostat was set at a constant 77 degrees.

Based on these results, Florida Power & Light suggests a Florida homeowner in an average-size home (1,770 square feet) can cut annual cooling costs 23 percent by choosing a white, galvanized metal roof rather than a dark gray shingle roof. White S-shape cement tile can save a homeowner 20 percent, while white, flat cement can save 17 percent. Homeowners in areas of the country that use air-conditioning less frequently can expect similar, although less dramatic, savings.