Air conditioners consume a great amount of electricity, making them both a financial and an environmental burden. The good thing is scientists are increasingly coming up with innovative ways to slash down our over-reliance on these cooling machines. For instance, just this week we wrote about a highly reflexive white paint that buildings can lather on in order to bounce hot sun rays and avoid absorbing heat. This time we present to you a a team of researchers who have managed to develop a ‘smart’ window that can quickly turn from clear to dark thanks to layers of nickel oxide, lithium ions, and electrolytes. By applying a current to the layers in the glass, a chemical reaction causes the window to become opaque. Windows made according to this formula can switch states quickly, blocking 94 percent of light within 60 seconds. If scaled up, the new technology could significantly reduce the need for air conditioning in buildings and vehicles, benefiting both the environment and our wallets.