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Home Window Efficiency Testing

About one-third of your heating and cooling are lost as heat transfers through your windows. While window technology has improved dramatically over the past 20-30 years, newer windows still contribute to home energy loss significantly. There are many things you can do to improve the efficiency of your home windows. The best place to start is with testing the efficiency of your windows to determine if it is time to invest in new windows, or if there are smaller improvements you can make to your existing windows.  

  1. The air leak test: Use a lit incense stick or match and hold it around the perimeter of your window. Any obvious air leaks should become apparent.
  2. Is there moisture or mold between the window frame and wall? Not only with this spread through your walls and is just all around bad for your health and home, but it is a sign of leaks in your window where heat can get in and out.
  3. Are there cracks in your caulk?
  4. Are your windows single or double pane? Double pane are significantly more efficient.
  5. What year were your windows installed? Many states enacted window efficiency standards in the early 1980’s. Windows prior to 1980 tend to be quite inefficient. Windows installed in the past decade tend to be fairly efficient.
  6. Check your weatherstripping and replace old felt weatherstrips with synthetics.
  7. Do your windows have energy efficiency films? If so, are they intact?
  8. Check your window frames: Wood and vinyl frames do not conduct heat, but aluminum does and is a poor choice in terms of energy efficiency. Fiberglass windows are becoming more and more popular and are one of the most efficient window frames.

If your house has a standard window-to-wall ration (12-14% of your home being window) and your windows are less than 30 years, you may want to hold off on purchasing all new windows, unless you noted significant concerns when going through the test above. Often small repairs, such as caulking, weatherstripping, and applying window film, can have a dramatic impact without the large financial burden. You may want to step back and do an overall energy efficiency audit to determine if replacing windows or repairing windows is the best use of your money, or if you may want to focus your resources on another source of energy loss.