Smarter Living: Energy

Take a look at your windows rather than out them if you want to save energy at home. Approximately one-third of a home's total heat loss usually occurs through windows and doors. What lets in light and fresh air may also be letting heat escape in the winter or unnecessarily heating up your home in the summer. But you don't have to replace your windows. Taking the time to seal and insulate around an old window can save money immediately while you decide whether to buy a replacement.

Save Money, Cut Energy Waste Through Your Windows

  • Use shades or drapes to help regulate the heat in your home. When it's hot outside, cover the windows on the south, east and west sides of the house. During cold weather, leave shades and blinds open on sunny days, but close them at night to reduce the amount of heat lost through windows. Insulating curtains or drapes can make a big difference, especially on sliding glass doors and large windows.
  • Applying "low-e" transparent film over drafty windows is a cheap, temporary fix for the winter months. You can also add weather stripping between the window and the frame to reduce heat loss.
  • If you have single-pane windows, consider replacing them, or put up storm windows in the winter. In cold weather, storm windows can reduce heat loss by 25 to 50 percent.
  • If you decide to go ahead and replace your older single-pane windows, make sure you don't miss the opportunity to save energy and reduce your future energy bills. Replace old windows with those that are at least Energy Star-rated for your climate.

Choosing New Windows

Replacing older single-pane windows with double- or triple-pane new ones that exceed Energy Star specifications can be a smart investment. As part of the federal stimulus package, homeowners can now claim a tax credit of up to $1,500 for new, energy-efficient windows, doors and skylights installed in 2009 or 2010.

The best type of window for your home depends on where you live. Energy Star-rated windows must meet requirements tailored for the U.S.'s four climate regions. Look for the National Fenestration Rating Council label on all Energy Star labels to compare important characteristics such as:

  • U-factor, which measures how well a window prevents heat from escaping. The U-factor measures the insulation ability of the entire window, not just the glass. For cold climates, a low U-factor is the most important consideration.
  • Solar heat gain coefficient (SHGC), whichmeasures how much heat from sunlight is transmitted through the window. Most of the country benefits from lower SHGC throughout the year, and if you live in Florida it is the most important thing for you to consider about your windows.

For the tax credit, you need a window with a U-factor of 0.30 or lower and an SHGC of 0.30 or lower. For more information about selecting new windows, see the Web site of the American Council for an Energy-Efficient Economy for a list of basic window features.

What You Can Do

  • Use shades or drapes to help regulate the heat in your home. In the cold months, leave shades and blinds open on sunny days, but close them at night to reduce the amount of heat lost through windows. In summer, keep shades closed to keep out heat.
  • Check for drafts around the windows in your home, and seal all window edges and cracks with caulk.
  • If you have single-pane windows, consider installing storm windows or replacing them with windows that qualify for the tax credit for home efficiency upgrades. Make sure to select windows suited for your climate and home by looking for a low U-factor in the north and low SHGC in the south.

Learn More

Energy Efficiency Tax Credits

last revised 11/15/2011

Get Updates and Alerts

See the latest issue >

NRDC Gets Top Ratings from the Charity Watchdogs

Charity Navigator awards NRDC its 4-star top rating.
Worth magazine named NRDC one of America's 100 best charities.
NRDC meets the highest standards of the Wise Giving Alliance of the Better Business Bureau.

Donate now >

Share | |
Find NRDC on