Do energy audit before buying windows



Replacing windows is an expensive proposition, so how do we know when it’s time to replace them? The first thing I always suggest is to contact your local electric cooperative about scheduling an energy audit. Trained staff can gather qualitative and quantitative information about the efficiency of your home, including the windows.

It’s not uncommon to discover through an energy audit that a home would benefit from a heating and cooling system tune-up or replacement, ductwork repair and sealing, air-sealing of unwanted air infiltration and additional insulation before targeting window replacement. If the audit shows the home is energy efficient except for the windows, then it might be a good candidate for replacement windows.

With so many window brands available, how do you know what is best? Energy Star and the National Fenestration Rating Council (NFRC) can help with the decision-making process. Energy Star tells us if the window meets geographic efficiency standards. The NFRC provides independent ratings in energy performance categories for brand comparison. As a personal recommendation, I suggest choosing NFRC products for the sake of an “apples to apples” comparison and the assurance of accurate performance ratings. Manufacturers who endorse NFRC are recognizable by the label displayed on each window. Each label contains information necessary to shop for and compare windows, including frame type, glass type, the U-Factor and Solar Heat Gain Coefficient (SHGC).

A good replacement window for Arkansas’ climate zone would have a vinyl or wooden frame. The double-pane glass would have a Low-E coating. The coating is applied for a Southern climate and helps reflect the sun’s radiant energy away from the home. The air gap between the panes would contain an inert gas like argon or krypton, which helps reduce heat transfer.  The U-Factor is an insulation performance number — a low number, like .30 or lower is better for our climate. The SHGC is a value for how well the window can resist unwanted summer heat gain. Again, a lower number is better — .25 or lower.

Remember that an energy audit should be the first thing you do before deciding to buy new windows. There is no way to accurately determine your energy savings for windows and other energy efficiency improvements without comprehensive pre-and post-energy audits.

To learn more about shopping for windows, energy performance ratings, comparing products and basic building science visit,, and www.smartenergy