Most Americans are probably aware that they can save energy and create a more comfortable indoor living environment by installing double pane windows, but by using spectrally selective coated glass, a double-paned window can save even more energy.

Spectrally selective glass, also called Low-E (lower emittance) glass, has a microscopic coating applied to the glazing that allows selected portions of the solar spectrum to pass through it, while restricting others. The lower emittance of solar heat in and outside the home will keep certain homes warmer in the winter, and others cooler in the summer depending on the climate, and will continually save money year after year over traditional glass. This is not the dark shaded glass of the past, in fact, today's Spectrally Selective glass appears virtually clear, allowing the daylight to brightly illuminate the home, making the most use of the sun's light to reduce indoor lighting cost.

There are varying types of Spectrally Selective Low-E coatings, with each variant more suitable for a particular climate zone. Windows that are energy efficient in Arizona, will not be appropriate for use in Maine. The Federal government's Energy Star program lists four climate zones in the United States and a recommended glass type for each. In order to gain the coveted Energy Star qualified rating, new home builders must install the Low-E glass determined for their particular climate zone.

For example, in the North/Central region of the country, Energy Star recommends, "Moderate Solar Gain Low-E Windows" which screen out a selected portion of the sun's heat in the summer, but allow a good amount of solar heat in winter. The inside window glass stays warmer, so you're not constantly feeling that drafty pull of chilly air assaulting your body, even though your thermostat is at 70 degrees.

In the Southwest portion of the country, energy efficient builders such as Pardee Homes (http://www.pardeehomes.com) use "Low Solar Gain Low-E Windows" which will screen the most heat from the sun and offer the greatest energy savings by keeping the home cooler during hot summers. These coatings also block ultra-violet rays, which greatly reduce the fading of fabrics, floor coverings, artwork, and window treatments.

For more information on Spectrally Selective Low-E glass, and other ways to save money by saving energy visit EnergyStar.gov.