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Earth Sense: Windows have better energy efficiency now
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A look around local building supply stores shows that window glass has changed considerably since the last century.

Most windows now show a greenish tint, which improves energy efficiency.

Although Georgia still uses the 2009 International Energy Conservation Code, the U.S. Department of Energy recommends looking for products with a IECC 2012 stamp. The savings in utility bills that are typically quoted range from 5 percent to 15 percent. It’s not huge, but new windows improve not only the household budget, but also the comfort level and appearance.

In most cases, replacing windows is not difficult. They come “pre-hung” from the supply center. This means there’s no fiddling with sliding rails, glass seals or angles. Removing the moldings around the existing window exposes the “raw opening” in the wall, which is a wooden frame in which the window resides.

Labels on new windows indicate the proper raw opening to fit. Some windows have a fin that gets screwed on from the outside, some don’t. Place the complete unit into the raw opening and secure it with screws or nails driven in diagonally from the wall frame.

Insulate open gaps with fiberglass wool pushed in loosely. Using expanding foam can distort the window frame and cause problems with opening and closing. There are foam products labeled “safe for window installation,” but fiberglass is still the safest.

After the window is in place, put on the new moldings, and after caulking and painting them you’re done. Vinyl-clad windows are especially nice because they never require paint and don’t get the black mold stains that exposed wood does.

The federal energy.gov site supplies more information about details such as the U-factor, which is the rate of heat flow that’s not from the sun. SHGC is “solar heat gain” and should be a number as low as possible.

Also important is whether to choose tempered glass or not. Every window within 2 feet of a door must be tempered.

This means the glass is treated to break into thousands of little pieces, instead of large, sharp daggers that can cause injury.

During severe storms, it’s important to keep away from windows. Tempered or not, broken glass caused by a branch hurled at the window is a hazard. The old urban legend urging us to “open the windows so the house won’t explode” is nonsense, if only for this reason.

Rudi Kiefer, Ph.D., is a professor of physical science and director of sustainability at Brenau University. His column appears Sundays and at gainesvilletimes.com.

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