Window U-Factor: How Effective Is Your Window’s Insulation?

window u-factor, window insulationIn past posts, we’ve discussed at length the importance of a window’s energy efficiency. One way this is measured is through the window U-factor. Very few homeowners are aware of the U-factor, though it’s an integral part of modern window installation.

What Is a Window U-Factor?

In a nutshell, the U-factor indicates a window’s ability to prevent warm air from escaping the home interior. The U-factor is especially a big deal in the winter. You want to retain as much heat as possible and keep heating costs to a minimum.

If your windows are really out of date, a window replacement with a good U-factor rating can slash energy costs up to 50%.

How the Measurement Works

The U-factor ranges between .20 and 1.20. Unlike most other measurement systems, the lower the figure the better (usually). That is, you want to gravitate towards a window closer to the .20 end. The measurement takes into account all parts of the window, including the glass, frame, and insulating materials. These components all have an effect on thermal transmittance.

To reduce U-Factor, manufacturers add a low emissivity coating to the window glazing. When indoor heat hits the window, the coating deflects it back and prevents heat from escaping.

Lower not Always Better

A higher U-factor rating enables more heat to escape. However, this is not necessarily a bad thing. This is actually desirable in regions with a hotter climate. However, while the Pacific Northwest has a relatively mild climate, it tends to lean slightly towards the cold end. In Washington, the recommended U-factor is lower than for a warmer region like, say, Arizona.

We Install Windows of All U-Factor Ratings

We install windows and siding as part of a home makeover. An initial inspection will determine a window U-factor that is right for your particular climate zone.

On the subject of window installation, we also have a special offer. From now until January, Exteriors Unlimited provides a $200 rebate for purchase and installation of seven or more windows. In addition, we also pay for your first month of heating bill following installation. Strike now while the iron is hot!

Energy-Efficient Window Installation

Serving Spokane, Spokane Valley, Liberty Lake, Medical Lake, Cheney, Sprague, Reardan, Spangle, Rockford, Fairfield, Edwall, Ford, Clayton, Deer Park, Colbert, Chattaroy, Mead, Airway Heights, Davenport, Ritzville, Nine Mine Falls, Rosalia, Oakdale, Tekoa, Colfax, St. John, Endicott, Springdale, Elk, Post Falls and Coeur d’Alene since 1984