Scientists have developed a 'smart' roof coating, made from waste cooking oil from fast food restaurants, which they claim could 'read' a thermometer and save energy in summer and winter.
A team in the US has developed the coating which automatically switches roles, reflecting or transmitting solar heat, when the outdoor temperature crosses a preset point that can be tuned to the local climate.
Roofs coated with the material would reflect scorching summer sunlight and reduce sticker-shock air-conditioning bill.
And, when chilly weather sets in, the coating change roles and transmit heat to help warm the interior, say the scientists.
According to team leader Ben Wen of United Environment & Energy LLC in New York, "This is one of the most innovative and practical roofing coating materials developed to date.
"This biobased intelligent roof coating, compared with a traditional cool roof, could reduce both heating and cooling costs as it responds to the external environment. It will help save fuel and electricity and reduce emissions of volatile organic compounds from petroleum-based roofing products.
"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."
Tests on coated asphalt shingles showed that the smart roof could reduce roof temperatures by about 50 to 80 per cent in warm weather.
In cooler weather, the coating could increase roof temperatures by 80 per cent compared with the traditional cool roofs.
In fact, by changing the coating's composition, the scientists can tune the substance so that it changes from reflective to transmitive at a specific environmental temperature.
"Even though the roof temperature is reduced or increased by a few degrees, depending on the outside temperature, this change could make a big difference in your energy bill," Wen said. In producing the coating, waste cooking oil is processed into a liquid polymer that hardens into a plastic after application.
The material is also non-flammable and nontoxic. The coating can be applied to virtually any type of roof.
"The coating can last many years and can be reapplied when it wears off. If further testing continues to go well, it could be ready for commercial use in about three years," say the scientists. The findings have been described at the National Meeting of the American Chemical Society.
