'Smart' windows that block out heat

Scientists are developing a new kind of "smart window" that can block out heat when the outside temperatures rise.

"Researchers are pursuing smart windows that can respond to a variety of cues, including electricity, gas, light and heat," said lead scientist Xuhong Guo from East China University of Science and Technology.

Current methods for making these windows use jelly-like materials called hydrogels that swell in the heat which hurts performance.

Guo, along with co-authors Kaimin Chen, Yanfeng Gao and colleagues made a version of the hydrogels but in the form of microscopic soft beads suspended in a liquid.

They sandwiched the solution between two pieces of glass and tested it using a model house.

When they shined a lamp mimicking solar light on the "smart window", it turned opaque and kept the house cooler.

The microgel, however, did not swell as much as its predecessor.

"The new microgel is a good candidate for use in future 'smart windows'," the team noted.

The breakthrough, reported in American Chemical Society's journal Industrial and Engineering Chemistry Research, could one day help consumers conserve energy in a better way on hot days and reduce electricity bills.