Excerpted from Real Goods Solar Living Source Book, edited by Doug Pratt and executive editor John Schaeffer.
Windows are the weakest link in any building s thermal barrier.
Until a few years ago a window was basically a hole in the wall that let light in and heat out. Nearly half of all residential windows in the U.S. only provide this negligible insulation value. In cold climates, windows are responsible for up to 25 percent of a home s winter heat loss. Install tight-fitting insulating shades. These shades incorporate layers of insulating material, a radiant barrier, and a moisture-resistant layer to help prevent condensation.