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Scientists today reported the development of a “smart” roof coating, made from waste cooking oil from fast food restaurants, that can “read” a thermometer. The coating automatically switches roles, reflecting or transmitting solar heat, when the outdoor temperature crosses a preset point that can be tuned to the local climate. They described the coating at the 239th National Meeting of the American Chemical Society (ACS), being held here this week. “This is one of the most innovative and practical roofing coating materials developed to date,” said Ben Wen, Ph.D., leader of the research project.
Scientists already have evidence that “white roofs” — roofs that are painted white to reflect solar heat and help cool buildings during peak summer weather — could significantly reduce global warming by lowering fuel consumption. However, white roof can have a wintertime heating penalty because they reflect solar heat that would help warm the building. So white roofs are a benefit in summer but a detriment in winter.
The new “intelligent” coating may sidestep this quandry. Tests on coated asphalt shingles showed that it could reduce roof temperatures by about 50 – 80 percent in warm weather. In cooler weather, the coating could increase roof temperatures up to 80 percent compared with the traditional cool roof. By changing the coating’s composition, Wen and colleagues can tune the substance, so that it changes from reflective to transmitive at a specific environmental temperature.