A clear window coating that lowers the temperature inside buildings could reduce the energy used to cool indoor spaces by 31%. It lets visible light through but blocks the sun’s infrared and ultraviolet rays, and radiates heat from the window at a wavelength that passes through the atmosphere into outer space. Researchers from Kyung Hee University in South Korea and the University of Notre Dame used computer modeling to design the coating, using alternating super-thin layers of common materials on a glass sheet, topped with a plastic film. They created many iterations using machine learning and advanced quantum computing, then made a film using the best design and tested it in Phoenix, AZ. The team calculated the energy it can save per year for a standard office with two windows in 16 US cities and several cities worldwide. The film could be made on large scale for practical applications, they said.