How to Choose The Best Energy Efficient Windows

Learn what to look for to save on energy costs. Replacing old windows with ENERGY STAR certified windows lowers household energy bills by an average of 12 percent. 

Double pane energy efficient windows

Thinking about replacing the windows in your home with more energy efficient materials?  According to, replacing old windows with ENERGY STAR certified windows lowers household energy bills by an average of 12 percent nationwide.  In addition to saving money, lowering your household energy consumption can also reduce greenhouse gas emissions and shrink your home’s carbon footprint, as well as other benefits that include:

  • Increased comfort
  • Coatings that reduce UV sun damage to interiors and contents
  • Performance certification
  • Protection from chills, drafts, and summer heat

Once you make the decision to replace your windows, you’ll have more choices to make regarding window materials.  The National Fenestration Rating Council (NFRC) is a non-profit organization that helps consumers who are interested in energy efficient windows, doors, and skylights. NFRC independently tests, certifies, and labels fenestration (openings in buildings) products to give consumers information about how well they will perform.  One rating component for windows is the U-factor, or the rate at which a window conducts non-solar heat flow. The lower the U-factor, the better the window’s energy performance.

There are many different types of window frame, glazing, and coating materials from which to choose.  The type of frame in particular can affect a window’s U-factor.  Vinyl, wood, fiberglass, and composite frame types generally offer better thermal resistance than metal.  In some cases, metal frames can be improved by installing an insulating thermal break.

After you’ve chosen a frame type, you’ll need to consider the different glazing and glass choices. You might even want to mix up the types for windows on different sides of your home depending on your climate and house design.  Your choices may include gas fills, heat absorbing tints, insulated glazing, low-emissivity coating, and reflective coating, as well as other options. 

To help you with these decisions and to find the right product, first determine your ENERGY STAR climate zone, and look for the ENERGY STAR label that is certified for that zone.  Make sure your windows are installed according to manufacturer’s instructions, and take care to seal air leaks that may be reducing your home’s energy efficiency.

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