Windows may be important for letting natural light and warmth into a room, but sometimes they let in too much, or let your artificial warmth out instead. Researchers at Oxford have developed a new smart window coating that can be tuned on the fly to emit or reflect heat from the Sun in different amounts, reducing the energy costs of heating and cooling by up to a third.
The key to the new tech is a chalcogenide-based material that changes phase in response to heat. In cold weather, this material absorbs the infrared rays from sunlight, and emits it into the room as heat. But when it’s hot out, the material can be switched to reflect heat from the Sun back outside, keeping the interior of the building cooler. In both cases, the idea is to reduce the use of climate control, which is one of the biggest guzzlers of energy.
The team also embedded small, transparent heater units into the coating, which activate the phase change material to different degrees. With this setup, the coating can be adjusted on demand to emit or reflect heat at different rates – so, for example, it could be set so 30 percent of the material reflects heat while 70 percent emits it.