Window science

In a serendipitous discovery, scientists at Lawrence Berkeley Laboratory and the University of California at Berkeley, USA, may have found an inexpensive material for making windows more energy efficient. While working on a way to boost the performance of a rechargeable battery, they put a transparent film of nickel hydroxide and titanium dioxide on glass. Surprise, surprise: it works like pho- , tochromatic eyeglasses, adjusting the brightness of the light hitting it.