Windows can be one of your home’s most attractive features. Windows provide views, daylighting, ventilation, and solar heating in the winter. Unfortunately, they can also account for 10% to 25% of your heating bill. During the summer, sunny windows make your air conditioner work two to three times harder. If you live in the Sun Belt, look into new solar control spectrally selective windows, which can cut the cooling load by more than half.

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 (e.g., low-e or spectrally selective) are available on the market. In colder climates, select windows that are gas filled with low-emissivity (low-e) coatings on the glass to reduce heat loss. In warmer climates, select windows with spectrally selective coatings to reduce heat gain. 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.

Cold Climate Window Tips

  • Graphic showing double-pane windows reflecting heat back into roomInstall exterior or interior storm windows; storm windows can reduce your heat loss through the windows by 25% to 50% – Storm windows should have weatherstripping at all moveable joints; be made of strong, durable materials; and have interlocking or overlapping joints Low-e storm windows save even more energy
  • Repair and weatherize your current storm windows, if necessary
  • Install tight-fitting, insulating window shades on windows that feel drafty after weatherizing
  • Close your curtains and shades at night; open them during the day
  • Keep windows on the south side of your house clean to maximize solar gain

Warm-Climate Window Tips

  • Graphic showing window with spectrally selective coating reflecting sunlight, keeping room coolerInstall white window shades, drapes, or blinds to reflect heat away from the house
  • Close curtains on south- and west-facing windows during the day
  • Install awnings on south- and west-facing windows
  • Apply sun-control or other reflective films on south-facing windows to reduce solar gain