Learning About Replacement Window Ratings

December 10, 2009

When buying replacement windows, there's plenty to consider, including window materials, styles, and the cost of the windows and their installation. Various ratings have been developed that measure the efficiency of window performance in various areas. Here are some replacement window glass ratings that you'll want to review before purchasing new windows:

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Ratings For Replacement Windows

  • U-Factor: This rating measures heat loss through windows. It is cased on a scale of .2 to 1.3, with lower scores indicating less heat loss.
  • Air leakage: This measures outside air leakage into your home from window frames, with fixed and awning window styles typically rated highest. The rating scale is between .1 and .3, with lower numbers being better.
  • Solar heat gain coefficient: Never mind the scientific sounding title of this rating. It measures how much sun penetrates through a window pane. This rating is measured on a scale of 0 to 1, with lower scores being better.
  • Condensation resistance: A common problem with multi-layer replacement windows is clouding between layers caused by trapped moisture. The condensation resistance rating measures a window's ability to resist condensation; in this case, the higher the rating, the better.

The significance of some of the ratings can depend on your climate, but learning how various replacement windows perform can help you make the best choice of replacement windows for your home.

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