Nanocrystal-studded windows could keep unwanted heat and light out, saving money

window

The same stuff that makes iPhone screens touch sensitive could lead to more efficient windows. Researchers at Lawrence Berkeley National Laboratory have developed nanocrystal-studded glass (subscription required) that can filter out visible and heat-producing light, allowing tighter control over how much heat and light can enter a building.

The “smart windows” are coated in a thin layer of crystals made from indium tin oxide — a transparent semiconductor commonly used on plasma, e-ink and touch-sensitive screens. The crystals are embedded in a glassy substance, resulting in a totally new material that can absorb up to 50 percent of the heat and 70 percent of the visible light that passes through it. The window would appear darker the more light it is set to filter out.

Smart window glass

“In the U.S., we spend about a quarter of our total energy on lighting, heating and cooling our buildings,” research lead Delia Milliron said in a release. “The most exciting part has been taking this project all the way from synthesizing a new material, to understanding it in great detail, and finally to realizing a completely new functionality that can have a big impact on technology.”

Nature reports that Milliron is currently commercializing the technology via an Oakland, Calif.-based startup called Heliotrope. The crystals can filter different amounts of light with an on/off switch, but first an additional film that carries voltage needs to be applied to the window. University of Texas-Austin materials chemist Brian Korgel told Nature the entire system might be too expensive for adoption.

Existing smart windows generally work by blocking visible, but not heat-producing, light. Harvard researchers recently reported that they could cool windows with silicon sheets packed with channels of water. As water flows through the channels, it pulls away heat, keeping it from traveling inside.

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