Window Replacement 101: An Introduction to Window Energy Efficiency & Cost Savings


Did you know that according to the U.S. Department of Energy, 10-25% of the energy you use to heat and cool your home is lost through inefficient windows? During the summer, your air conditioner must work harder to cool hot air from drafty windows, and cold drafts entering your home during winter are an important sign that it’s time to replace your windows. But will window replacement really help you save energy and money? The answer is a resounding YES!

How Much You’ll Save

According to ENERGY STAR®, upgrading old single-pane windows to more energy-efficient units can help your household save anywhere from $126 to $465 per year. Your exact savings will depend on climate, local energy costs, home orientation and construction, and your windows’ energy efficiency ratings.

Understanding Energy Efficiency Ratings

To be sure you’re buying energy-efficient products, it’s important to understand window efficiency ratings. Window efficiency is measured by the following ratings displayed on the Department of Energy’s blue-and-yellow ENERGY STAR label, and the white National Fenestration Rating Council label.

  • U-Factor. U-factor is a measure of how well a window prevents heat from escaping your home. The lower the number, the better. This measurement is particularly important in cold northern climates.
  • Solar Heat Gain Coefficient (SHGC). Solar Heat Gain Coefficient is a measure of how much of the sun’s heat is blocked by a window. The lower the number, the less heat that comes through the glass.
  • Visible Transmittance. Visible Transmittance is a measure of how much light a window lets in. The higher the number, the more light is admitted into your home.
  • Air Leakage. Air Leakage is a measure of how much air a window lets in. The lower the number, the better.
  • Condensation Resistance. Condensation resistance is a measure of how well a window resists the formation of condensation on its inside surface. The higher the number, the better.

Learn More about Sunrise® Windows

Watch the video to learn more about popular window types, including double- and single-hung windows and picture windows, then explore the options for your home with the Design Your View virtual tool. Visit to locate an authorized Sunrise® Windows & Doors dealer near you.


About the Author

Joseph Mills

Joseph Mills

Joe Mills is the Director of Marketing for Sunrise Windows and Doors. He has spent almost 15 years working with homeowners helping them envision and design home improvement projects. He is proficient in assisting homeowners through their entire buying process, including helping them do the proper research, what signs to look for to minimize a homeowner’s risk, understanding the in home selling process and once the decision is made, how the installation process will work. He has written a consumer-oriented book called “How To Buy Vinyl Replacement Windows” that can help window buyers make educated choices.