Breaking Down Window Energy Efficiency Ratings

When you're in the process of shopping around for new windows, you will most likely notice the yellow energy efficiency sticker attached to each one. This sticker may be very confusing to you if you are unfamiliar with the different rating factors on it. Here's what you should understand about the ratings to know which window is best.


The window's U-factor translates to how well the window prevents hot air from seeping outside of your house. A high number in this category actually identifies a window that is less efficient. U-factor is important to focus on if your home is in a climate that sees very low temperatures throughout the winter.

Solar Heat Gain Coefficient (SHGC)

The SHGC essentially means how effective the window is at blocking the sun. Similar to U-factor rating, lower is better if you want a window that does a great job at blocking the sun's rays. A low rating is ideal for homes in warmer climates, where you want to prevent the sun from warming your home. It will cause your air conditioner to work less to get your house to a comfortable temperature.

Visible Transmittance

The visible transmittance of a window is just a fancy way of saying how much light it allows into the home. The higher the number, the more daylight it lets in. This is a factor you can improve on your own later by adding a window tint, but you cannot modify a window with high visible transmittance to let in more light.

Air Leakage

Air leakage is important for homes in both hot and cold climates. This rating is a measurement of how much outside air is let in through the window. A lower rating means the window does a better job at keeping air outside the home.

Condensation Resistance

The rating for condensation resistance measures how well the window resists condensation buildup. This factor plays less into your energy costs and more into the damage that can be caused by a window. Excessive condensation can cause damage to the window frame if it is made out of wood, the wall beneath the window, and the carpeting. A higher rating will be a window that has less condensation buildup.

Keep in mind that energy ratings are just one factor you need to consider when purchasing new windows. Work with a local window contractor when it comes to replacing the windows in your home. To learn more, contact a business like Beyers Window & Door Inc.