HIGH PERFORMANCE WINDOWS

Many scientists now say that global climate change is underway due primarily to the burning of fossil fuels and the resulting build-up of carbon dioxide and other "greenhouse gases" in the atmosphere. Climate change threatens human health and well-being because it causes more severe storms and droughts, rising sea levels, increased spread of infectious diseases, and other adverse effects.

While policy makers and nations debate a tougher international treaty to curtail greenhouse gas emissions, there is much that we as individuals can do in our homes and workplaces to reduce our contribution to global warming. The good news is that many of these actions can save money as well as protect our environment.

Windows account for around 25% of the heating and cooling bills in a typical home, due to heat loss through windows in the winter and heat gain in the summer. Homeowners may be paying $200 per year to heat and cool the outdoors, thanks to their windows. Along with this bill comes increased burning of fuel in power plants and at home, and more emissions contributing to global warming, urban smog, and acid rain.

High performance windows are now available that can dramatically cut this energy bill and pollution source. These windows feature double or triple glazing, specialized transparent coatings, insulating gas sandwiched between panes, and improved frames. All of these features reduce heat transfer, thereby cutting the energy lost through windows.

Consumers now have a reliable way to identify energy-efficient windows, thanks to the National Fenestration Rating Council (NFRC), an independent organization. NFRC labels for windows and skylights are similar to mileage rating stickers on new cars.[See sample NFRC label below.]The label’s "U-factor" rating measures how much heat escapes through the window -- the lower the U-factor, the less heat lost. In colder climates, consumers should select windows with a low emittance ("Low-E") coating and/or an insulating gas fill, to achieve a U-factor rating of no more than 0.35.

For hotter climates where air conditioning dominates, the label’s "Solar heat gain" rating measures the sun-shielding ability of the product. The lower the rating, the less solar heat is transmitted through the window. Consumers should select windows with a "Southern" low-E coating and a solar heat gain rating of no more than 0.40.

If all windows were as efficient as the best products now widely available in the marketplace, the environmental benefits would be enormous. Energy use due to heat flows through windows would fall by about 70%. The typical household would cut its carbon dioxide emissions by about 4,300 pounds per year and the United States would reduce its annual emissions by about 430 billion pounds, or 3 % of total US emissions.

Installing high performance windows is also a smart investment. The extra cost for upgrading to the "best technology" at the time new windows are needed will cost a typical household about $600, but would lower its heating and cooling bills by about $150 each year. Since new windows should last 20 years or more, investing in high performance windows would yield a 20-40% return. Not bad, considering the 5% or so return offered by most consumer savings accounts.

Energy savings aren't the only benefits provided by efficient windows. They increase comfort, reduce condensation on windows, and transmit less ultraviolet radiation that can fade drapes, carpets, and furniture. So when buying a new home, constructing an addition, or replacing drafty existing windows, consumers that choose high performance windows will benefit their family and their planet.