About a third of the energy consumed by buildings goes out the window. So efforts to reduce energy use in homes and offices have naturally focused on windows, with varying success. While there are all kinds of smart glass—from electrochromic to suspended particle displays—many are expensive, degrade after relatively short periods, or present environmental problems during manufacturing processes. Many U.S. companies and research organizations are trying to better these early designs. But one of the most promising pieces of research now comes via South Korea, where a group of researchers say they have developed a simple, inexpensive system with minimal environmental impacts.
Like other smart windows, their proposed design becomes more or less transparent according to the light outside, darkening to save air conditioning bills on hot days, and letting in warmth on cold days to reduce heating costs. But unlike other designs, it does so automatically, without users having to use a control to dim or brighten the effect.
Writing in the journal ACS Nano, the researchers claim that by using a polymer, "counterions" (ions with an opposite charge to the substance they associated with) and methanol in layers inside the pane, they can create a low-cost, stable window with extreme switching ability. The glass turns from completely clear to completely opaque in a matter of seconds.
"To our knowledge, such extreme optical switching behavior is unprecedented among established smart windows," they say. "This type of light control system may provide a new option for saving on heating, cooling and lighting costs through managing the light transmitted into the interior of the house." And it doesn't hurt that smart windows will probably impress your friends, too.