One microgel closer to smart windows of the future
December 10, 2014 - Windows allow natural light to stream into homes and buildings but, along with light comes heat that, in warm weather, we often counter with energy-consuming air-conditioning. Scientists are now developing a new kind of ‘smart window’ that can block out heat when outdoor temperatures rise.
By Anthony Capkun
Reported in the American Chemical Society’s (ACS) journal “Industrial & Engineering Chemistry Research”, the advance could one day help consumers better conserve energy on hot days and reduce electric bills.
Xuhong Guo, Kaimin Chen, Yanfeng Gao and colleagues explain that researchers are pursuing smart windows that can respond to a variety of cues, including electricity, gas, light and heat. Those that are sensitive to heat are particularly useful for cutting down on energy use: when it gets hot outside, the windows turn an opaque white to block unwanted heat from entering a building while still allowing light to pass. They become transparent again as temperatures drop.
Current methods for making these windows use jelly-like materials called hydrogels that swell in the heat that, according to researchers, hurts window performance. Guo’s and Gao’s teams are addressing this flaw.
Building on previous advances, the researchers 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 shone a lamp mimicking solar light on the smart window, it turned opaque and kept the inside of the house cool, and the microgel did not swell as much as its predecessor. The researchers conclude their new microgel is a good candidate for use in future smart windows.