Windows: Passive House Glazings and Fenestrations

Windows: Passive House Glazings and Fenestrations

Extremely Energy Efficient Pazen ENERsign Passive House Windows Thermal Performance

There are a large number of window manufacturers around the world, most with names you may not have heard of before.  In the U.S. market names such as Andersen, Jeld-Wen, Simonton, Pella, and Marvin, may come to mind.  Less known is Serious Windows.  Finding a U.S. manufacture that produces windows well suited for passive house construction is most challenging as most are two pane designs.  I believe this circumstance is changing for the better.  I hope energy efficient triple-pane passive house windows--with the proper performance characteristics will eventually become the norm domestically. 

But currently, there are many other windows--passive house ready--that offer high(er) levels of performance (and construction quality).  Germany is generally regarded as producing the finest and best windows for passive house in the world (for a price).  Exceptional windows are also available from other European countries.  Examples include Pazen Fenstertechnik, Schüco, Optiwin, Gradwohl Fenster und Haustüren, Bieber, and Intus.  Some of these manufactures produce certified passive house windows.

Purchasing high-end extremely energy efficient windows from Europe for U.S. consumption has historically been difficult, lengthy, and expensive, however even since the time we began our construction (nearly two years ago), they have been easier to obtain through an increasing U.S. presence.  As a consequence, we may have selected a different manufacturer--which produces windows specifically tailored to Passivhaus--if we were starting construction today.

Canada is a good source for high performance windows that possess similar characteristics to their European counterparts--often for less cost and manufacturing lead-time.  Manufacturers include: Thermo-Tech, Fibertec, Inline, Accurate Dorwin, and Loewen.

When comparing energy efficient windows from different manufacturers (especially from abroad), be aware that how windows are rated vary, so directly comparing them may not be as apples-to-apples are one would anticipate.

Our particular window and door selection of Loewen was certainly one of the limiting components of our passive house, as their u-values and shgc values were well short of those of the highest performing certified passive house windows and doors.  This specific area of "weakness," especially since we had so many windows--some quite large--had to made up for in other areas of our passive house construction, such as an extreme airtight building envelope.



  1. Hi Bob.
    I've been following your blog closely as we are in the final design stages of our passive house, being built in Eastern Ontario, Canada. What windows did you end up purchasing? And if you had the choice to make again, which of the Canadian-made windows would you have chosen?

  2. Hello Mimi.

    Congratulations one your Passivhaus project!

    We ultimately selected Loewen for several reasons:

    1) They had a local presence in our area (retail)
    2) They are stunning in their design and appearance
    3) They have, what I believe, very good air-tightness
    4) Their engineering department was a pleasure to work with and they developed customized designs for our project that weren't being offered at the time.

    I will discuss our experiences in greater detail in a future article. It is difficult for me to say we would make a different choice today. We had consider AD but their materials limited the ability of making a radius and curved design and we were also going for aesthetic beauty, not just technical performance as one of our design goals was to have a beautiful appearing luxury home, not a scientific project.

    We also looked at Serious, but we had some reservations about a number of aspects of them.

    If we had a choice today, I think we would have certainly considered some of the imports from across the pond as they appear to be more readily available now.

    We used A LOT of windows, even on our North side, which is a no-no, of course. But, we wanted an extremely naturally "bright" and warm home and we have a terrific view out back that we did not want to lose.

    Beyond our articles, if you have any other questions feel free to contact us via my email.

    We completed our project, although the blog has been lagging quite a bit. Nearly 2 1/2 half years from design to finish! (Ouch)

  3. Hello,

    Best wished everybody with such a great choice to build a Passive House. I just finished my project too! Actually I had two of them.

    We decided to go with Intus Windows. One of the cases was kind of specific, the house was at 9000 ft. Intus Windows explained all the process and even agreed to take a look at drawings. It seemed that there are some misunderstandings there so they did some configurations. Excellent job! So they installed capillary tubes during transport. We didn't have any problems with the tubes as they equalize pressure. Windows fit and perform perfectly till now.

    Regarding good experience we chose Intus windows for the next project too. We picked aluminum triple pane energy efficient windows and curtain walls, R6. Intus Windows use Schuco products as I read have very good reputation in Europe. The delivery was right on time, we got extra hand helping with drawings and installation, superb airtightness, performance outrages our requirements, they even offered us the price other companies offer for double pane windows!

    I would strongly recommend to order windows from smaller companies, they just care about customers more. Good luck with your projects!

    Bob Mo.

    1. Hey Bob,
      Now that your windows are in and functioning (and you've ordered more!) could you say something more about what you like about them? We are about to put in an order with this company. I particularly wonder about how they handle screens. Thanks for anything you care to share.
      An insanely complicated business.... picking triple-pane!

    2. What we liked about Intus products is performance of the hardware, durability, how well they block noise and how warm they are to touch. Condensation on the edge of the glass was an issue with our old windows but not anymore because warm spacers prevent that from happening. Considering that aluminum frames are more likely to transfer cold I like that these frames have full thermal brake.
      I know that they have fixed and pull-down screens which are good. I didn't purchase screens but I had a chance to see them in a showroom. I should say they looked pretty high quality.

  4. Just want to make you aware: Marvin Windows and Doors now offers a wide range of American-made wood windows that will meet both European and U.S. passive standards. Certification from both bodies is pending and expected shortly.

    More info here:

  5. Passive House Institute Certifies First U.S. Window

    Casagrande Woodworks Inc. has received the first window frame certification in the United States from the Germany-based Passive House Institute for its Synergist model all-wood outswing casement. The window has a thermal transmittance (Uw) of 0.79 W/(m2K) with Passive House Efficiency Class A (advanced component), it is reported.

  6. More info on the first US Passive House window certified by Germany-based Passive House Institute can be found here:


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