Windows and Window Shades

Even when a home's walls have been well insulated, doors and windows can be responsible for up to 50 percent of the heat loss that takes place in winter. Air can seep through cracks around door and window frames, and heat can be transferred directly through the glass and frame through the process of conduction.

Sealing air leaks, or even replacing old windows with vastly improved new models, will go far to improve a home's energy efficiency. Loosely fitting windows can lose up to five times more heat than tightly fitting ones, so even if homeowners can't afford to replace old windows, they can help to minimize their losses by checking for drafts around windows and doors on windy days. Any leaks should be sealed with weather-stripping. Gaps or holes should be caulked and windows should be kept tightly locked to prevent drafts.

Use window coverings to control the loss or gain of heat in your home. Storm windows and insulated shades keep heat in during the winter while solar screens, reflective film, drapes and shutters can keep heat out during the summer.

-- from Energy Excerpts

"New window technologies allow windows to perform better than insulated walls as energy savers. A key technology in these products is low-emissivity or low-e coatings (special coatings that transmit light but not heat.) Combined with insulating frames, double glass and non-heat-conducting filler gases such as argon, the new generation of windows is use ... can let builders create efficient homes with larger glass areas.

Research shows that windows account for about 25 percent of the heating and cooling energy used in buildings, and about 5 percent of total national energy use. Low-e windows can save more than half of the energy lost through older windows. Their use has grown to about one-third of the residential window market, saving consumers about $350 million a year and avoiding about 4 million metric tones of carbon emissions!"

-- from Building Technologies,
Solar Energy Industries Association handouts on ECOS, Summer 1996

For more information on the ever-improving technology of energy efficient windows, visit the home page of the National Fenestration Rating Council (NFRC).

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