A group of scientists with funding from the Department of Energy has presented a new type of roof coating that would allow all the benefits and none of the drawbacks of black and white roofs combined.
It's long been agreed that a white roof, because it naturally reflects sunlight, reduces the amount of heat a building absorbs in extremely hot and sunny situations, thus, contributing to keeping the building cool (think Greece). Some have even gone as far as to propose white "green" roofs as a geoengineering idea for reducing global warming because they may both reduce air conditioning use and reflect more sunlight back into space if used en masse.
Meanwhile, a black roof absorbs sunlight and can help reduce building heating needs in places with cold but sunny winters (think Boston on a good year).
But wouldn't it be nice if you could have it both ways?
A new "smart roof" coating invented by a group of scientists from the research and development company United Environment & Energy offers that option. The liquid polymer made from fast-food waste oil hardens into plastic once applied and dry. It then reflects strong sunlight in hot weather but switches roles to absorb and transmit heat in cold weather.
It can be applied to any type of roof, according to the scientists. When tested, it showed a decrease in roof temperature between 50 and 80 percent in warm weather when compared to regular asphalt shingles, and an increase in roof temperature by 80 percent in cold weather.
"This is one of the most innovative and practical roofing coating materials developed to date," Ben Wen, leader of the research project and vice president of United Environment and Energy, said in a statement. The project was funded in part by a grant from the Department of Energy.
"In addition, it will provide a new use for millions of gallons of waste oil after it is used to cook French fries and chicken nuggets," said Wen.
But, Wen noted, the coating does not smell like French fries as with most fast-food waste oil. Instead, the group's polymer coating is "virtually odorless."
The polymer invention was presented in March at this year's 239th American Chemical Society national conference in San Francisco.