Courtesy of Andersen Windows
Q: We recently bought a home with windows from the 1960s that are drafty. We’d like to replace them with energy-efficient windows. Can you offer any tips?
A: Replacing your windows is often the most costly and least cost-effective energy-efficiency investment you can make. But there are reasons besides energy efficiency to invest in new windows, such as comfort, resale value and aesthetics.
Think about your goals. If reducing your energy costs is important, weigh an investment in new windows against other energy-efficiency opportunities. An energy audit by a qualified auditor (resnet.us) will help you determine how leaky your windows are and compare your options.
Some windows, even old ones, are not as leaky as you might think. You may have more significant air-leakage problems elsewhere in the home.
There may be options for reducing heat loss through your windows without replacing them, such as storm windows or window coverings.
Are you happy with the number, size and location of your windows? You may want to increase or decrease the size of a window or replace a window with an exterior door. Sometimes, these types of changes are quite affordable; however, the cost can be much greater if significant changes to wall framing are required.
When considering whether to add windows, remember that even very efficient ones are much less effective insulators than a home’s exterior walls, which means they will be colder to the touch than the wall in the winter. Depending on orientation and shading, windows can let in too much direct sun in the summer, driving up indoor temperatures and air-conditioning costs.
Window buyers have a number of choices to make. Double-pane windows are necessary to meet code for most applications, but the additional cost for triple-pane windows could be worth the investment if you live in an area with extreme temperatures. Argon or krypton gas between the panes adds a little more efficiency.
A common option that can be well worth the investment is a low-emissivity coating added to the glass. The most important benefit of this “low-e” coating is its ability to reflect heat back into the interior space, which reduces heating bills and increases comfort. These coatings reduce solar heat gain as well, which can help with air-conditioning costs.
Window frames can be made of wood, composite materials, fiberglass, aluminum or vinyl. Each has pluses and minuses in terms of cost, maintenance, durability and energy efficiency.
Fortunately, windows are rated for energy efficiency, so you don’t need to know all the details about their construction. The most important indicator of a window’s energy efficiency is the U-factor, which measures the rate the entire window loses heat. Lower U-factors are more efficient. The window framing material, the number of layers of glass and the special coatings on the glass all contribute to the U-factor. In more extreme climates, it makes sense to have more efficient windows.
Another indicator to look for is the Energy Star label. Only windows that are substantially more efficient than the code requires receive the Energy Star label. The Energy Star website (energystar.gov), maintained by the U.S. Department of Energy, has a climate-zone map and a list of windows, doors and skylights that qualify for the Energy Star label.
Work with a professional installer. Poor installation can result in long-term damage, including moisture problems that can create mold, mildew and rot in the wall, prevent the window from operating properly or cause paint to peel.
Bids for new windows vary a great deal. Request more than one, and compare qualifications as well as price for windows that will change the look and comfort of your home for years to come.
Send questions to Energy Q&A, South Carolina Living, 808 Knox Abbott Drive, Cayce, SC 29033, email energyqa@scliving.coop or fax (803) 739-3041.