As I write this, I pause to gaze out the window in front of me into the Vermont woodland that is my backyard: ferns nestled beneath granite outcroppings, the gnarled trunk of an ancient sugar maple accented with a few fallen leaves already golden in the advancing season. This north window in my study connects me to the outdoors, even while protecting me from the drifting snow and wind that will soon be coming. Through the other window one facing east a refreshing breeze wafts in the screened opening, enlivening my study with the crisp, fresh air of autumn and connecting me to the sounds of the outdoors: a late-season medley of crickets and songbirds.
From an environmental standpoint, decisions we make in selecting windows are among our most important especially as those decisions relate to energy. In a new house, windows typically account for 15 to 30 percent of the total heating load and often over half of the summertime cooling load. The 1.2 billion residential windows in the United States account for 3.2 percent of our national energy consumption, according to researchers at the Lawrence Berkeley National Laboratory, and 9 percent of residential energy consumption.
Beyond simply serving as a barrier to unwanted heat loss or heat gain, however, windows can be energy providers selectively introducing beneficial passive solar heat in the winter or natural lighting year-round. Through careful design, they can do this even while serving the vital function of protection.
Check out the January/February 2000 issue of Natural Home for more on eco-friendly windows, including:
• How to prevent heat loss from windows
• Boosting energy performance of windows with air space, low-emissivity coatings and low-conductivity gas fill
• Selecting windows with an eye on environmental materials