cooling costs

A group of recent Massachusetts Institute of Technology graduates has developed a roof tile that remains white in summer to reflect the sun’s energy then turns black in winter to absorb the sun’s rays and heat buildings.

The so-called “thermeleon” (rhymes with chameleon) technology uses a common commercial polymer trapped between layers of plastic, including a black layer at the back. When the temperature drops, the white layer disappears, exposing the black layer.

The MIT graduates say the tiles reflect about 80 percent of the sun’s heat when they are white, translating into a 20 percent savings in cooling costs. When the tiles turn dark, they absorb about 70 percent of solar energy.

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