You can save money on your energy by understanding how windows work to help you control your energy costs. Windows are great for views, ventilation, and daylight, but can be a source of heat loss in the winter and heat gain in the summer. Windows are responsible for about 10 - 25% of your home's winter heating bill. Unwanted solar heat gain through windows in the summer can make your air conditioner work two to three times harder. (source: EREN)

Window Recommendations

Whether you are building a new house or replacing windows, the following recommendations will help you choose windows that are just right:
  • Choose windows with good warranties against the loss of the air seal. If the glazing seal is lost, low-conductivity gas between the layers of glass will immediately be lost and fogging will occur.
  • Look for the NFRC label as your guide to their energy performance. The U-factor measures the window's ability to insulate; the lower the U-factor, the more efficient the window.
  • Select windows with low air leakage ratings between 0.01 and 0.06 cfm / ft.
  • To ensure that your new windows perform as well as they should, hire a skilled contractor to install them.
  • To maximize energy performance, choose windows with large, unbroken glazing areas instead of multi-pane windows. Applied grills that simulate multi-pane windows are fine, as they do not reduce energy efficiency.

More Information

For additional information on energy-efficient residential windows, check out these related websites: 
  • Efficient Windows - This website provides unbiased information on the benefits of energy-efficient windows, descriptions of how they work, and recommendations for their selection and use.
  • Energy Star - Energy Star-labeled windows can keep your house comfortable and help save money on utility bills through superior designs that require less money and less energy.
  • National Fenestration Rating Council - NFRC is a nonprofit organization created by the window, door, and skylight industry to develop a window energy rating system based on whole product performance.