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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

"I'm getting ready to do my 2nd round of window installation with Anderson Windows. I really appreciate the great financing options that they offer! They have top notch sales and installation experts who are very kind and considerate of their customers' wishes. The windows I have installed look great and I am so excited to get the next group of windows put in. My house looks so much brighter with my new windows. I definitely recommend Renewal by Andersen of St. Louis."

Connie Klinginsmith-Rehfeld
Feb 2, 2024

"We recently contracted with Renewal by Andersen to replace 5 windows in our home. First of all, we were very delighted that the time from contract to installation was less than two months. Joel and Craig arrived precisely at the agreed-upon time and spent less than four hours from start to completion of installation, including time to demonstrate opening/closing the windows and any questions we had. We were very pleased with the knowledge and professionalism of Joel and Craig, and, of course, we’re very pleased with the windows and how nice they look. We definitely recommend Renewal by Andersen."

Marla Merenghi
Feb 1, 2024

"I replaced my front door and several windows. The install team did a great job with installation and clean up. Even covered floors and stairs. The team was very courteous and did a very professional job. Now our windows look great and we love our new door. I would recommend Renewal by Anderson in a heartbeat."

Rose Brown
Jan 25, 2024

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