Energy Star Windows

ENERGY STAR ratings have been around for more than 20 years. It started in the United States as a way to signify products that generally use 20 to 30 percent less energy than their counterparts, and it’s since been adopted by a range of other countries including Australia, Canada, New Zealand and Japan as well as the European Union. Today consumers know to look for the ENERGY STAR logo when shopping for appliances, but not everyone knows they can purchase ENERGY STAR doors and windows. Installing ENERGY STAR windows is a good way to cut cooling and heating costs down for your home.

What Makes an ENERGY STAR Window?

There are two main deciding factors that determine whether a window is ENERGY STAR certifiable or not. They are the U-factor and the SHGC (solar heat gain coefficient). The U-factor determines how easily heat flows through a window, with lower numbers being more restrictive and the SHGC shows how much heat-causing light can travel into a home, with a lower number signifying a lower level of heat traveling into the home.

The type of windows you will need depends largely on what climate you live in, the ENERGY STAR rating for windows fluctuates based on climate. In northern climates a low U-factor and higher SGHC are necessary to receive an ENERGY STAR certificate and in southern climates a low U-factor and lower SGHC rating is necessary to get the certificate. That’s why it’s so important to buy the right ENERGY STAR windows depending on your location.


Window ENERGY STAR Requirements by Region

Here are the guidelines by region for ENERGY STAR to certify different windows.


  • U-factor= .30 or lower with any SHGC
  • U-factor = .31 with an SHGC of .35 or higher
  • U-factor = .32 with an SHGC of .40 or higher

North Central Guidelines

  • U-factor= .30 or lower with
  • SHGC = .40 or higher

South Central

  • U-factor = .30 or lower and SHGC = .25 or lower


  • U-factor = .30 or lower and SHGC = .25 or lower

energy star regions


While ENERGY STAR window requirements are stringent, skylight requirements aren’t as strict. The U-factor can be considerably higher and the SGHC doesn’t have to be as low in Southern locations. Even though the requirements aren’t as strict, you should still pay attention to these ratings. Having a low u-factor skylight installed in a Northern home will allow a decent amount of heat to escape from your home.

Skylight ENERGY STAR Requirements by Region

  • Northern – U-factor = .50 or lower
  • North Central – U-factor = .53 or lower with an SHGC of .35 or lower
  • South Central – U-factor = .53 or lower with an SHGC of .28 or lower
  • Southern – U-factor = .60 or lower with an SHGC of .28 or lower

Do a Bit More Research

ENERGY STAR ratings are a good place to start when shopping for windows, but just picking out a window because it is an ENERGY STAR window isn’t the best strategy. Some ENERGY STAR windows are much more efficient than others. Some are much more durable and some are worth the investment while others are not. Working with a window professional will help you choose quality windows that will be a good investment for the long term.

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