Researchers at the University of Chicago have designed a new building material that can control the temperature inside buildings in a more energy-efficient way. When installed on the outer walls of buildings, this electrochromic material can emit or absorb varying amounts of infrared radiation based on outside temperature, keeping interior temperatures at safe and comfortable levels. The material contains a central layer that, when triggered, can assume one of two states: solid copper, which can retain heat and keep buildings warm, and a watery solution, which can reflect heat and keep buildings cool. According to the researchers, this smart material is more energy-efficient, because the amount of electricity needed to switch between the heating and cooling modes is negligible. Moreover, it could lower the cost of heating and air conditioning, as well as reduce the energy and carbon footprint of buildings, which account for nearly a third of global energy consumption and a tenth of all global greenhouse gasses.