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Engineers Have Developed A “Smart Window” That Can Lighten Or Darken In Under a Minute

Stanford University engineers have developed a “smart window” that can lighten or darken in under a minute — faster than conventional dynamic windows. The new technology could be used to optimize lighting in buildings and vehicles, significantly reducing heating and cooling costs. The results are published in the Aug. 9, 2017, issue of Joule magazine.

image/text credit: energy.stanford.edu

Commercially available smart windows are made of materials, such as tungsten oxide, that change color when charged with electricity. But these materials tend to be expensive, have a blue tint, can take more than 20 minutes to dim and become less opaque over time.(more info: energy.stanford)

The Stanford prototype blocks light through the movement of a copper solution over a sheet of indium tin oxide modified with platinum nanoparticles. When transparent, the window is clear and allows about 80 percent of surrounding natural light to pass through.


When dark, the transmission of light drops below 5 percent. It only takes about 30 seconds to change from transparent to dark or vice versa.To test durability, the researchers switched the windows on and off more than 5,000 times and saw no degradation in the transmission of light.