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Air Leakage: How It Affects a Window’s Energy Efficiency

Remember, a one-size-fits-all approach won’t work in choosing a new energy-efficient window. Everyone knows you should look for an ENERGY STAR® certification, but how do you pick one from dozens of windows that have that label? You look at its U-factor, solar heat gain coefficient (SHGC) and air leakage rating (AL) ratings.  

What the AL Rating Means 

The AL indicates the amount of air that can pass through a square foot of a window. A window with an AL of 0.1 lets in the least amount of air while a window rated 0.3 lets in the most amount of air. However, this doesn’t mean you should avoid windows with a rating that’s more than 0.1 – as long as the AL is below 0.3, the window can be considered energy-efficient. 

Here’s a tip: if you’re looking for a window with a low AL, try looking for double-pane replacement windows

How Does It Affect Your Home’s Energy Efficiency?

Of course, drafty windows, ones with a rating of more than 0.3, can raise your power costs; heat and air-conditioned air can leak out of your home, forcing your HVAC unit to consume more power to maintain a comfortable temperature inside. 

How to Pick the Right Window 

However, keep in mind that although a window’s AL is an important aspect, it isn’t the only one. When evaluating window performance, you need to factor in its several other features. One feature can’t make a window entirely energy-efficient. Our energy-efficient windows have a variety of features like Fibrex® frames with excellent insulation capabilities and ultraviolet-blocking High Performance™ Low-E4 glass. 

One more thing: make sure only a qualified company installs your new energy-efficient windows. Installation errors can leave behind gaps, which can then let in drafts. 

Renewal By Andersen® of St. Louis, an independently owned retailer with an A+ rating from the Better Business Bureau, offers a wide variety of premium windows and doors. To schedule a free consultation with one of our design specialists, call us at (314) 983-9977, or fill out our contact form here. We serve homeowners in Chesterfield, MO, as well as other nearby areas.

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"Renewal by Andersen of St. Louis performed EXACTLY as the commercial illustrated. We were able to book an appointment on a Sunday. Matthew was our representative and he was great!"

Melanie Matthew | RBA OF ST. LOUIS, MO - MARYLAND HEIGHTS
Sep 27, 2021

"The product is excellent, the salesman were very knowledgeable about it, the installers were helpful and did an excellent and efficient job. I would highly recommend using this company."

Maria Marafioti | RbA of St. Louis, MO - Maryland Heights
Sep 16, 2021

"The salesman had previously sold us new windows and was very informative and not a bit pushy. The installation was excellent and as advertised absolutely nothing was left for me to clean up. Highly recommend Renewal by Andersen of St. Louis👍"

Elizabeth Ham | RBA OF ST. LOUIS, MO - MARYLAND HEIGHTS
Sep 25, 2021

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