"Stop throwing money out your old windows," some commercials say. With heating costs on the rise, many homeowners may wonder whether it's time to replace aging, drafty windows with efficient, tight-fitting ones.
In addition to reducing your energy bill, new windows can make your home more comfortable, quiet, and attractive. But don't expect to recoup your investment right away. If you now have old-fashioned single-glazed windows, replacement windows might save you from10 percent to 25 percent a year for heating and cooling. But new windows cost from $7,000 to $20,000 for an average house, and custom sizes can add another 15 percent. So it might take 20 years or more before you break even. That's why you might want to wait until your old windows have deteriorated, when you're remodeling, or when you want windows that are easier to wash and maintain.
Replacement windows have become more energy efficient since insulating features such as multiple glazing, Low-E coatings, and inert-gas insulation have proliferated in many manufacturers' lines. We tested replacement windows for air and water leakage, durability, and convenience. Here's what we found.
Manufacturers mark their replacement windows with a U-factor, a measure of a window's ability to conduct heat. The U-factor is the reverse of the R-value, which is a measure of insulating ability. The lower the U-factor or the higher the R-value, the better a window can keep your home cool in summer and warm in winter. The R-value may be better known to the general public, but manufacturers avoid listing it because it might seem less impressive. The R-value of the very best windows is about 2 or 3, equivalent to that of an uninsulated wall. The solar heat gain coefficient is shown as a fraction and indicates how much of the sunlight that hits a window makes it inside as heat. For cold climates, look for the highest SHGC number you can find; in warm climates, 0.40 or less; temperate areas, 0.55 or less. Visible transmittance measures how much visible light a window lets in. The higher the VT, the better.
Finding an installer
Even the best windows won't deliver the look, comfort, or savings you expect if they're installed poorly. Many major window manufacturers, including Andersen, Marvin, and Pella, train and certify installers for their specific products. Using the same contractor for purchase and installation can minimize the chances of problems arising later. Readers who used an installer recommended by the window manufacturer were more satisfied overall than those who used contractors employed or recommended by Home Depot or Lowe's, according to our Home Improvements Survey. Also look for certification from the American Window & Door Institute (www.awdi.com).
Before work begins, read the installation instructions for the windows you've chosen online, and check that the installer plans to follow those instructions, right down to details such as type, amount, and placement of flashing and insulation. Deviating from the manufacturer's recommendations could void the warranty. If you plan to paint the windows, have the installer use acrylic-latex caulk, which can be painted, not silicone.
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