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Energy Efficient Windows

Alpen has provided windows in the Arctic Circle and to the Empire State Building. Learn more about the brand in this story.

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Casino with advertisement for Alpen Windows | Construction Pro Tips

Alpen windows and doors

Alpen has been producing high performance super-insulated windows and door products for over 30 years for both residential and commercial buildings to keep your home or business as comfortable and energy efficient as possible. Alpen has provided windows in both Antarctica and the Arctic Circle and have supplied windows to the Empire State Building that are designed for 110-mph winds.

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Cut away of the inside of an Alpen window | Construction Pro Tips

Uber-efficient windows

Alpen’s current entry level windows, the Zenith Series ZR-5, perform better than most of their competitors best windows. These are a fiberglass frame window that you can get in a casement or slider style. You can expect whole window (outside frame to frame) R-values at R-4.8 to R-5.9  For an example: standard windows with a single pane of clear glass has the equivalent R value of R-1.  This Zenith Series offers options for a full frame window of up to R-10 in the ZR10 series.

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Snow pushed up against a building with Alpen windows | Construction Pro Tips

What’s so important about super-insulated doors and windows?

Windows are essentially holes in an insulated wall. These “holes” in the wall are intended to provide views, light, ventilation and egress. A window manufacturer’s ultimate goal is to make a high performing window that insulates/performs as well as an exterior wall. This allows builders and designers to have the option of using larger windows, while still achieving high performance R values throughout the whole wall which can be very difficult to do.

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A cutaway of Alpen's best windows | Construction Pro Tips

Best windows

The Alpen Tyrol Series has the highest NFRC whole window rating of any window manufactured in North America. The frame is made from a proprietary combination of uPVC and fiberglass reinforcement that is forming a high-tech composite (similar to material you would normally see only in race cars or jet aircraft) this high-tech composite combines strength and insulating performance. Alpen then adds additional insulation in the frame, then a high-performance glass.

With these European style fixed frames, or tilt turn/hopper windows, you can expect whole window values ranging from R-5.6 to R-10, depending on what glass option you go with. That’s almost as much as some wall assemblies!

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Two men inspecting an Alpen window | Construction Pro Tips

What makes Alpens high-performance products unique?

There are a few very important (and unexpected!) things you should know about windows before selecting the one that will work best for you:


-In North America, the most recognized performance-rating system for windows is a label listing the window’s verified capabilities. This information is also maintained in the product directory of the National Fenestration Rating Council (NFRC).
-The NFRC label provides energy performance measurements based on rigorous standardized testing and was designed to provide verified information to consumers. This allows consumers to be confident in any energy performance claims made by a manufacturer.  This is non-bias testing that won’t allow anyone to “fluff’ their numbers.
-Alpen windows have the highest NFRC certified whole window ratings of any window manufactured in North America—at R-10 (U-factor of 0.10). Alpen also maintains ratings/certifications from the American Architectural Manufacturers Association (for verified structural integrity), Passive House (for high performing buildings) and the Living Building Challenge Declare Program (for super-healthy buildings).

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Woman making an Alpen window | Construction Pro Tips

Custom-crafted in the factory

Alpen does not stock any pre-made products. Every window shape, jamb, color, and style are made for specific projects. And each glass package is unique as well. A (sunny) west-facing windows shouldn’t be exactly the same as a north-facing window. Every Alpen window, door and glass unit is custom-crafted to exact specifications. There are less expensive windows on the market, but it would be tough to find a better one.