Harvard’s Engineering team has been working a new form of glass that will help with letting the sunlight in, nothing beats natural light, while keeping the heat out. This will be done by applying this thin layer of silicon rubber. This silicone works like the living animals, it dilates when the surface is hot, causing less heat to get in. This could be extremely beneficial to keep electricity bills down, due to it working both ways in summer letting less heat in, while in the winter taking in as much heat as possible. It will also benefit the solar system industry, as it can help keep it cooler, and what electric apparatus likes the heat?

Source: http://www.seas.harvard.edu/news/2013/08/self-cooling-windows-let-in-sun-without-heat