Air conditioning and heating have made it easy to control the temperature inside our homes, but both can get pretty expensive. This high-tech window film is designed to solve that problem by letting in the sun's heat on cold winter days, while blocking it during the dog days of summer.
Developed by scientists at Japan's National Institute of Advanced Industrial Science and Technology (AIST) working in collaboration with Sumitomo Chemical, the film leverages the fact that the sun sits higher up in the sky during the summer months than it does in winter. The film consists of a sandwich of two plastic layers, and it is the boundary between these layers that is engineered to reflect back the sun's energy if it strikes the window at a sharp angle, while letting it through if it hits the sheet directly.
This sounds intriguing, but we see a few potential problems. Of course the sun rises and falls all the way to the horizon every day, that's how we get sunrises and sunsets. Sure, it ends up going higher by midday in the summer, so we suppose the reflective trick will work during the hottest part of the day. The other problem is that this sounds like it would work only with windows that get hit with direct sunlight. Still, we suppose every little bit helps.
Sumitomo says that they are still working to improve the effectiveness of the film, but they say we should expect to see a commercial product on store shelves within two to three years.