Our Double Hung Windows Have The Best Air-Infiltration Rating Of Any Window In Minneapolis—And It’s Not Even Close.

If you’re a Minneapolis homeowner looking for new double hung windows, it’s important to know about air infiltration before you make a buying decision. Poorly-made double hung windows can leak air from several areas, causing uncomfortable drafts and higher energy bills.

Here’s what you need to know about window air infiltration—and how our vinyl double hung windows are literally 23-times more airtight than wood double hung windows.

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Window Air Infiltration: The Basics

Energy Star is the standard for energy efficient consumer products in America. Energy star measures the efficiency of windows in a number of categories. One of these categories is Air Leakage (AL). As with all of a window’s ratings, you can find AL on the window’s NFRC label:

energy performance ratings for vinyle double pane window
The NFRC label with AL circled in red.

AL gauges how much air will penetrate the window itself (this does not include around the frame—we’ll get to that in a minute). The amount a window leaks air is represented as a number between 0.1 and 0.3 on the NFRC label; the lower the number, the better a window protects against air leakage. For instance, a window with an AL rating of 0.18 will be more airtight than a window with an AL rating of 0.27.

Here is a simple rule of thumb when examining a window’s AL rating:

  • 0.1 is excellent
  • 0.2 is good
  • 0.3 is average and the bare-minimum industry standard
  • Any window over 0.3 is not accepted by Energy Star
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Leak-Prone Areas Of A Double Hung Window

Poorly-made double hung windows can leak air from numerous areas. These areas include the sash meeting rail, the sill, and the sash perimeter.

Here’s a diagram of potential leak areas of a double hung window:

the points of air infiltration through a window
Air can leak through the sash meeting rail, sash perimeter & sill of a double hung window.

Why do substandard double hung windows leak air from these points? For several potential reasons.

The window may be made with inferior parts. Or it could be manufactured poorly. Or it may not contain the necessary features to stop air leaks, such as weather stripping and built-in airlocks. Whatever the reason, it all means a drafty home and higher energy bills for YOU.

Why Zen Twin Cities Has The Industry’s Most Airtight Double Hung Windows

Since the best AL rating on the NFRC label is 0.1, it cannot express how much more airtight OUR double hung windows are.

Our lines of vinyl double hung windows have an AL rating between 0.01 and 0.07. Note that extra decimal place—that means our windows are MUCH more airtight than Energy Star’s BEST air-leakage rating!

When you see all the air-leak-proofing features packed in our windows, it’s easy to see why:

  • High-density Comfort Foam
  • Ultra-Smart triple-fin weather stripping
  • Soft-Seal straddle gasket
  • Dura Sill’s double-walled sill dam

To put in perspective just how much better our windows block out air, let’s compare our vinyl double hung windows to other window brands and materials:

  • The best WOOD double hung windows from big-name brands such as Pella and Marvin have a median AL rating of 0.23. That means our best vinyl double hung window is 23 times more airtight than the best double hung wood window!
  • The best VINYL double hung windows from manufacturers such as Champion and Alside have a median AL rating of a0.15. That means OUR best vinyl double hung window is 15 times more airtight than theirs.
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Will Installation Affect Air Infiltration In A Window?

Yes. But that is not something expressed on a label in as a numerical value. The NFRC label measures air leakage only through the PRODUCT itself. It doesn’t factor in air that may leak around the frame. This means even the window with the best AL rating in the industry can leak air if it’s improperly installed.

That’s why it’s so important to choose an experienced Minneapolis window company with a PROVEN track record to install your double hung windows.

Here Are Some Ways To Know If A Window Company Is High Quality:

  1. They have an ample amount of customer reviews you can read and references you can call.
  2. They have plenty of job photos, so you can gauge their work.
  3. They have lengthy warranties (preferably lifetime) on installation AND materials, with no fine print or exclusions.
  4. They have the proper liability insurance and necessary licenses.
  5. They have an owner who is actively involved and invested in the outcome of your project.

If you’d like to know how Zen Windows Twin Cities can guarantee you superb installation and a completely stress-free experience, visit the Why Choose Us section of this website. Then feel free to get an online quote on our Request A Quote page. We’ll provide you with an accurate, ironclad price and the information you need to make the right decision. No pressure. No pricing games. Period.

Steve Copsey
Owner