Global Challenges/Chemistry Solutions

Our Sustainable Future: “Smart” roofs that can save energy

August 26, 2010



Conventional roofing shingles (top)
and shingles with a “smart” coating
(bottom) that could save energy and
lower bills by adjusting to
temperature changes.
Credit: Ben Wen, Ph.D.


Summary

Scientists are reporting development of a “smart” roof coating,
made from waste cooking oil from fast food restaurants, that
can “read” a thermometer and help save energy. Roofs coated
with the material would reflect scorching summer sunlight and
reduce sticker-shock air-conditioning bills. When chilly weather
sets in, the coating would change roles and transmit heat to
help warm the interior. Scientists described the sustainable
material at the 239th National Meeting of the American
Chemical Society in San Francisco.

Choosing the most energy-efficient roofing material for homes, schools, and businesses is no simple matter. Top a building with a light-colored “cool roof,” and it reflects sunlight, cutting air conditioning bills in summer, but increasing winter heating costs. Choose black shingles, and the roof soaks up sunlight to cut winter heating costs but makes the roof bake in the summer sun. One or the other. You can’t have it both ways….until now. Ben Wen and colleagues of United Environment & Energy in New York are developing a “smart” roof coating that can “read” a thermometer. The material is made from waste cooking oil from fast food restaurants. The new coating automatically switches roles, reflecting or transmitting solar heat when the outdoor temperature crosses a pre-set point that can be tuned to the local climate. Dr. Wen is also vice-president of the company. He described the research at the 239th National Meeting of the American Chemical Society in San Francisco.

Here is Dr. Wen:

“This is one of the most innovative and practical roofing coating materials developed to date. This amazing new coating can read a thermometer. It is also sustainable.”

Roofs coated with the material would reflect scorching summer sunlight and reduce sticker-shock air-conditioning bills. When chilly weather sets in, the coating would change roles and transmit heat to help warm the interior.

Here again is Dr. Wen:

“This bio-based 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 of asphalt shingles covered with the “intelligent” coating 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 can either reflect or absorb heat at a specific environmental temperature.

Dr. Wen describes the benefit of this technology for consumers:

“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.”

In producing the coating, the scientists process waste cooking oil into a liquid polymer that hardens into a plastic after application. Unlike raw waste oil, which can smell like French fries or fish, the resulting polymer is virtually odorless. The coating contains special chemicals that allow it sense and respond to temperature changes. Manufacturers could potentially produce the roof coating in any shade, ranging from clear to black, depending on what additives are used. The material is also non-flammable and nontoxic.

Who knew that left-over cooking grease might one day help people cut energy bills and fight global warming?

Smart chemists. Innovative thinking

Smart chemists. Innovative thinking. That’s the key to solving global challenges of the 21st Century. Be sure to check our other podcast on Our Sustainable Future: Decomposing BPA-containing plastic using a “fungus among us. Today’s podcast was written by Mark Sampson. I’m Adam Dylewski at the American Chemical Society in Washington.

Ben Wen, Ph.D.,
Ben Wen, Ph.D., Image courtesy of United Environment & Energy