From Eco-Logical Innovations, a highly insulative window that keeps your home both cool and warm.
The KSD window consists of three panes of glass, one of which (the center green pane) reflects heat away in one direction. When the green side is turned outside towards the sun, it will reflect heat from the sun back to the outside, keeping the house cool. So for winter, you can pivot the window to bring the green side in - thus, keeping the heat from leaving.
There is no word on how much an average home will save, but the numbers should be substantial.
The windows have been on sale in Germany for a few years and has just entered the U.S. market.