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Replacing old windows

Except for siding and roofing, new windows have the biggest impact on the overall appearance of your home. And a window's attraction isn't limited to the home's exterior. Depending upon the material and style chosen, a new window can dress up the interior of a room too.

Energy-efficient windows can make your home more comfortable by eliminating drafts in winter and preventing heat gain in summer. Higher-end windows with an R-value of 6 or more can save more energy than common double pane (insulated) windows. You enjoy the best of both worlds -- allowing sunshine to warm your home in the winter and preventing solar gain in the summer, thus keeping your home cool/warm depending on the season. The result is a more stable interior climate and reduced demand on your home comfort system-heating and air conditioning. That means less energy use, lower utility bills and home comfort equipment that won't work as hard, and consequently will last longer.

If you're window shopping, we have two words of advice for you: "Energy Star." It's a government-backed program that helps individuals and businesses protect the environment through superior energy efficiency. In one year Energy Star rated products saved enough energy to power 15 million homes and avoid greenhouse gas emissions equivalent to those emitted from 14 million cars. It says a lot that a home improvement that has such a positive effect on the value of your home also has such a profound effect on our environment and economy.

Using new technology in frame materials, glass coatings, design and gas fills, today's Energy Star qualified windows, doors and skylights lead to significant energy cost savings.

The facts:

*Energy Star-qualified windows today are, on average, twice as efficient as the average window made only 10 years ago.

*Energy Star-qualified windows, doors and skylights can help reduce your energy bills up to 15 percent. Over the lifetime of a typical window, the return on investment can be substantial. And, saving energy prevents pollution.

*Energy Star-qualified windows, doors and skylights also provide increased comfort, noise reduction and protection against sun damage to carpet, vinyl wood flooring, window treatment, fabrics and even artwork in your home.

*To achieve maximum energy and pollution savings when window shopping: Look for windows, doors and skylights with the Energy Star label.

*Check the U-factor -- the rate of heat transfer either from your home or the outside through your window, door or skylight. A lower U-factor means less heat is transferred.

*Be aware of the Solar Heat Gain Coefficient (SHGC)-how much heat your house gains from the sun. A lower SHGC results in less heat gain from the sun.

*Consider climate: Windows, doors and skylights are tailored to fit the energy needs of the country's four main climate regions: northern, north central, south central and southern.

*Learn about energy-efficiency horsepower. All Energy Star qualified windows, doors and skylights also bear a label from the National Fenestration Rating Council (NFRC), which provides independent energy performance ratings by product for U-factor, solar heat gain coefficient, and visible transmittance.

There are three basic means of window replacement installation:

1. Install a retrofit window that fits inside the old wood frame. While there are many variations on this process, the basics are the same: A new frame -- generally aluminum or vinyl -- is custom built to fit into the old one. In retrofit installations, built-in wooden flashings reduce any water infiltration between the old and new frames. These flashings work well but don't always offer the best aesthetics.

2. Saw the old frame out and install the new window in a thick bed of caulking and/or foam on all four sides. This technique is used primarily for aluminum and older-type steel windows. With all windows, leaks are a primary concern and this process has the most potential for developing leaks because caulk may dry out and shrink or separate from the frame as a result of normal house movement and settling.

3. Install a new window. In our opinion, this is the best option. It also happens to be the most disruptive and costly. All exterior wall covering gets removed; the old window is taken out completely (including the flashing) down to the studs; and the new window and flashing is nailed in place, covered with siding paper, and caulked and sealed from face of stud to exterior trim. This way, you have three or four layers of protection between the outside elements and the interior of the house.

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James Carey and Morris Carey are nationally recognized experts on home building and renovation.