Windows let in light, keep out heat

Quite a lot of U.S. energy consumption goes out the window, literally. Now, nanotechnology could produce a coating for glass that is affordable and effective at saving energy.

Windows are wonderful for flooding the indoors with light, but they are also a drain on energy. In the cold-weather months, they let out heat that should be kept inside. In summer, they let in too much heat, which necessitates running air conditioning. Scientists at Lawrence Berkeley National Lab, California, have now developed a nano-crystal coating that gives more control over the light spectrum, and therefore how much near-infrared light (which produces heat) and visible light enter a room. The window appears completely clear, even when little heat is entering.

“When used as a window coating, our new material can have a major impact on building energy efficiency,” says researcher Delia Milliron, who adds that it should be possible to link the glass to a climate control system so it would respond automatically to conditions in the room.

Milliron says the new smart glass is cheaper than current technologies because it doesn’t involve any special hardware. More work needs to be done before the product is ready for market, but developments are promising.