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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.

Reviews

"The installation crew was very professional and answered what questions I had. And they cleaned up when they were finished. We're very pleased with our windows & patio doors. Highly recommend Renewl by Anderson."

Pamela D
Feb 13, 2023

"Very pleased with installation of six windows and a ProVia entry door. I love the look of the windows and door. I am pleased that my wife is thrilled with the look of the door. She is very pleased that the bronze color fits in well with the color of the brick."

Terry S
Feb 8, 2023

"I just had my Renewal by Andersen windows installed and couldn’t be happier, the entire process went very smoothly. The windows are high quality and look great. But the installers Roy, Zack and Jordan were the stars, they introduced themselves upon arrival walked me thru everything they were going to do and when they finished took me to each window to make sure I was completely satisfied. They were clean and courteous and I would definitely recommend and have them work in my home again."

BOB B
Feb 6, 2023

"Wonderful experience with knowledgeable, competent employees. We had Andersen windows in a previous house & didn’t even consider anything else this time. After replacing our patio door almost two years ago, we replaced all our windows this year. What a difference over builder-grade windows, especially in the really cold temperatures we’ve had this year. Andersen windows may be a little more expensive than other brands, but they are top quality."

Susan S
Jan 31, 2023

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