How to Choose Energy Efficient Replacement Windows

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Replacing windows is a significant, long-term investment for homeowners, so choosing the right windows among the plethora of options available today is extremely important. Yet weeding through replacement window choices at your local home improvement center or window dealer showroom can be intimidating. Luckily, the National Fenestration Rating Council (NFRC) is here to help. NFRC’s residential window labels can help consumers quickly compare the energy performance of windows, doors, skylights and other fenestration.

How to Choose Energy Efficient Replacement Windows So, what do you look for when choosing the right replacement window for your climate? Two of NFRC’s ratings should be top of mind: U-Factor and Solar Heat Gain Coefficient (SHGC). By understanding these ratings, you can make an informed decision when comparing energy efficient replacement windows, which can help save you money on heating and air conditioning costs.

  • U-Factor measures how well a window prevents heat from escaping a building and is rated from 0.09 to 1.20. The lower the U-Factor, the better the product is at keeping heat from escaping.
  • SHGC measures how well a window blocks the sun’s heat, and is rated on a scale of 0 to 1. A lower SHGC means that the product is better at blocking unwanted solar heat.

Before heading out to purchase your new replacement windows, contact your local building permits department to inquire about your community’s energy requirements for residential windows. Having this information on hand will make your purchasing decision simpler as you will know which ratings are compliant with local energy codes.

When you are finally ready to purchase your replacement windows, look for the NFRC rating label on each window to compare products. Like the gas mileage sticker on a new car, these labels allow you to quickly compare which windows are in the specific ratings range that you need.

For more than 20 years, consumers, architects, contractors and building code officials have trusted NFRC’s ratings. In fact, to be eligible for the ENERGY STAR® label, windows first must be NFRC-rated. NFRC’s focus on uniform, accurate and unbiased ratings makes it the recognized leader in arming consumers with the energy performance information they need for windows and other fenestration products. For more information, visit

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