White Hats | Green Energy News

August 22, 2004 – Vol.9 No.22

WHITE HATS.

Light-colored, light-reflecting roofs are the good guys for houses. They can save money on air conditioning bills.

However, Americans like dark roof colors - shades of gray, brown, green and deep red.

(Americans also like to travel to tropical areas where roofs are often bright white to reflect heat, but don’t bring this energy, money-saving idea home.)

From a solar reflective standpoint clean white metal or tile roofs can reflect up to 70 percent of the sun’s energy. Weathered white roofs (white, a little dirty) can have a solar reflectance of 25 to 55 percent. At 55 percent reflectivity cooling costs can be reduced up to 20 percent. Conventional dark roofing will reflect only 5 to 25 percent of sunlight.

Fortunately scientists at Berkeley Labs, working with companies in the roofing industry, understand how stubborn homeowners can be about their roof color and have developed a database of cool color pigments that are both dark in appearance but light reflective. The database of available pigments will become a reference tool for roof manufacturers who want to offer energy saving roofs based on light reflectivity.

Those pigments are being tested with roofing materials such as metal, tile, and asphalt shingle for their manufacturing feasibility and market acceptance.

The cool-color pigments that achieve a solar reflectance of 25 percent, or higher, will qualifying for an Energy Star (tm) cool-roof label as well as being qualified as a cool roof in the new version of the California building energy code, the upcoming 2005 Title 24 California Building Energy Efficiency Standard.

Visit Berkeley Labs at http://enews.lbl.gov/ , Energy Star Roofs http://www.energystar.gov/index.cfm?c=roof_prods.pr_roof_products and the California Building Energy Code, Title 24 http://www.energy.ca.gov/title24/