U. S department of Energy, has developed a new material in windows that could control the amount of heat and light that gets through the window inside the building.
Simply it means that a window will allow natural light to pass through but without unwanted heat. This would reduce need for A.C or heating etc.
Delia Milliron, a chemist at Berkeley's lab, said that, "we spend about a quarter of our total energy on lighting, heating and cooling our buildings".
The technology in the "Smart Window" can block light and heat, people inside buildings have the facility to customize the climate depending on their choice if more or less light and more or less heat.
The coating in the window technology is made of "nanocrystals".