Researchers at Lawrence Berkeley National Laboratories have developed a technology that prevents solar heat gain without blocking visible light, allowing for “smart windows” that can respond to outdoor conditions without a visible change in the window.
At present, electrochromic window coatings can block near-infrared radiation, which causes heat gain, but only by darkening the window at the same time; this can lead to increased use of indoor lighting and offset the energy benefits of smart windows. The new technology uses a transparent nanocrystal coating of indium tin oxide—a semiconductor used in flat-screen TV displays.
The coating could allow for the creation of smart windows programmed to work in tandem with HVAC and lighting systems by selectively allowing heat to pass and always allowing light to pass—thereby reducing heating, cooling, and lighting loads.
Researchers also reported that the new coating requires less electricity in order to work compared with typical electrochromic coatings, making it more efficient in its own right. For more information, see www.newscenter.lbl.gov.