Windows can be one of a home's most attractive features. Windows provide views, daylighting, ventilation and solar heating in the winter. Unfortunately, they can also account for 10 percent to 25 percent of a heating bill. During the summer, sunlight streaming through windows can make an air conditioner work two to three times harder.
If your home has single-pane windows, as almost half of U.S.
homes do, consider replacing them. New double-pane windows with
high-performance glass also called low-e or spectrally
selective are available on the market. In colder
climates, select windows that are gas filled with
low-emissivity coatings on the glass to reduce heat loss.
If you are building a new home, you can offset some of the cost of installing more efficient windows because doing so allows you to buy smaller, less expensive heating and cooling equipment.<
If you decide not to replace your windows, the simpler, less costly measures listed below can improve the performance of your windows.
Double-pane windows with low-e coating on the glass reflect heat back into the room during the winter months.
New windows are long-term investments that have a large impact on a home's energy systems. Today, there are many new window technologies available that are worth considering, especially those with the ENERGY STAR® label. Glazing materials now come with a variety of selective coatings and other features. Frames are available in aluminum, wood, vinyl, fiber glass or combinations of these materials. Each type of glazing material and frame has advantages and disadvantages.
Source: Tips for Energy Savers, U.S. Department of Energy