Choosing Energy Efficient Windows for Your Home

What to look for when buying energy efficient windows.

Published April 7, 20213 min read

There are many benefits to getting new windows. One of the perks is the chance to lower your home’s energy bills, since windows directly affect how much energy is used to heat and cool your residence. 

According to the U.S. Department of Energy, heat gain and loss through your windows accounts for 25%-30% of the energy needed to keep your home at a comfortable temperature. If you’re able to reduce this amount with new energy efficient windows, you could be spending less on energy costs. It’s estimated that ENERGY STAR® rated windows save homeowners an average of 12% on their heating and cooling bills.

How to choose energy efficient windows

Not all new windows are energy efficient; some will be better than others and there’s no easy way to tell if a window is efficient or not. As a result, homeowners must rely on endorsement programs like ENERGY STAR®. The ENERGY STAR® symbol is the stamp of approval that the window meets or exceeds efficiency guidelines set by the U.S. Environmental Protection Agency (EPA). However, alongside that symbol there must also be:

  1. An ENERGY STAR® label showing the geographic area where the product is certified for use in.
  2. A National Fenestration Rating Council (NFRC) label detailing the window’s energy performance ratings. 

You can see a sample of the two labels on the ENERGY STAR® website. Together, these two labels contain a lot of information, however, it’s only useful if you know what numbers to look for and what they represent.

How to read the labels

The ENERGY STAR® label map is a quick visual on whether the windows are suitable for your area. The windows you buy for a home in Wisconsin, Minnesota, Iowa, North Dakota, or South Dakota, for example, are vastly different than the windows you would buy for a home in Arizona or Texas. It’s essential that the windows are rated for the area you live in.

The NFRC label lists the ratings given in four categories that are key to a window’s energy efficiency: U-Factor, Solar Heat Gain Coefficient, Visible Transmittance, and Air Leakage.

  1. The U-Factor represents how well a window keeps heat in a room. It ranges from 0.20 to 1.20. The lower the number the better.
  2. The Solar Heat Gain Coefficient represents how well a window keeps unwanted heat out (like in the summer). It ranges from 0 to 1 and you want to look for low numbers here as well.
  3. The Visible Transmittance rating signifies how well the window lets light in. The more light allowed, the higher the number and the less you’ll have to rely on lamps during the day. The rating ranges from 0 to 1.
  4. The Air Leakage rating measures drafts, how easily outside air is making its way in. The lower the number the better and the rating should never be more than 0.3.

Types of windows and window features to consider for energy efficiency

Even with an ENERGY STAR® endorsement, some types of windows are more energy efficient than others. When comparing windows, keep the following in mind: 

  • Avoid metal frames where possible, as they conduct heat rapidly. Instead, consider vinyl options.
  • Single-glazed windows (i.e. one pane of glass) are generally less efficient than double-glazed windows.
  • The space between panes isn’t just air (or shouldn’t be). It should be filled with krypton or argon gas to minimize heat transfer. Krypton contributes to energy efficiency more than argon, but it’s more expensive.
  • How the window opens. To minimize air leakage, consider awning style windows (hinged at the top and opens outwards), hopper style (hinged at the bottom and opens inwards), or casement windows (hinged on the side).  

Get a free, no obligation quote for energy efficient windows

Get the most out of your energy efficient windows with a Fleet Farm SERVICEfinder window installation professional. Our window specialists are local contractors from your community who will help you select windows that are stylish, complementary to your home’s overall design, and energy efficient, all with expert installation.

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Energy Star® is a registered trademark of the U.S. Environmental Protection Agency.

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