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Green Building News

New Ways to Find High-Performance Windows

Two new companies can help builders choose or order the right windows for Passivhaus and other high-performance projects

High-performance windows like this vinyl window from Prossimo are a cornerstone of Passivhaus designs, but they're not always easy to find. Builders now have two new options for sourcing them. [Image credit: Prossimo]

Builders and designers looking for high-performance windows now have two more options: a New York-based distributor specializing in European windows suitable for Passivhaus buildings and an online evaluation service that makes window recommendations for specific building designs.

The window company is Prossimo. [Editor’s note: After this article was written, the company changed its name to Mavrik Windows.]  The company’s co-founder is Ben Freed, who with no prior experience acted as his own general contractor and built a net-zero energy home for about $170,000 after being told it couldn’t be done.

The difficulty of obtaining high-performance windows convinced Freed and his friend Jared Madsen to form partnerships with window manufacturers in Poland, Lithuania, and Estonia and sell them in the U.S.

Freed said by telephone that Prossimo helps builders navigate the differences between European and U.S. made windows, including sizing, colors, unit sizes, glazing packages and hardware. Launched in May, Prossimo has so far imported windows and doors for five projects, Freed says, and is the first high-performance window company focused on the affordable market.

“Our main offerings are not Passivhaus-certified,” he said. “They are Passivhaus-suitable. The U-factors you get are able to get you to certification on your project. To be cost-effective, that’s the approach we’re taking. The actual certified windows are the next level up from what we offer right now. What we offer now, the R-7.5 range, is more than enough to get you a certified Passivhaus.”

Prossimo arranges for fabrication with its European partners and has the windows or doors shipped directly to the user. They’re sold under the Prossimo label. The lead time is between 10 and 12 weeks after the builder makes a deposit.

Freed pledged to sell operable tilt-and-turn windows with triple-pane glazing and an R-value of 7.5 for $25 per square foot. Fixed windows sell for $17 per square foot.

Builders can get quotes through the Prossimo website.

Free window consulting

The frustration of finding suitable windows for high-performance designs prompted New York architect Michael Ingui and several partners to launch a website called Fentrend.

“Finding the right window at the right place, comparing windows, has been so difficult,” Ingui said by telephone.

Working with plans or elevations submitted by builders or designers, Fentrend compares windows that would be suitable for the project and sends back a report that lists available windows, sizes, different performance levels, plus contact information for applicable manufacturers. The process typically takes about five days, Ingui said.

There is no charge for the service. “It may not be the most lucrative business model,” he said, “but it’s a good service.”

More than two dozen window companies have signed on with Fentrend to participate in comparisons of features and specs.

In one instance, a client who had been planning to install “crappy aluminum windows” from a New York City company sent plans to Fentrend, which later recommended Klearwall windows from Ireland. They saved the customer $10,000 on a $400,000 window package, and while the windows weren’t Passivhaus-certified, they outperformed the original windows by five times, Ingui said.

As a result, heating and cooling equipment in the building could be much smaller and less expensive than planned.

“It’s a pretty significant difference,” he said.


  1. ben_prossimo | | #1

    Hi everyone!
    Hi GBA community. If anyone has any questions about our products, (sorry, the website is a little thin at the moment) feel free to post them. I'll be glad to answer them!

  2. nvman | | #2

    400k window package?
    Is that a typo?

  3. GBA Editor
    Martin Holladay | | #3

    Response to Aaron Gatzke
    It was probably a large commercial or institutional project -- not a single-family home.

  4. user-5226143 | | #4

    Response to Aaron Gatzke
    Sam here with Fentrend. We've been seeing project sizes ranging from $4k to over $1 mil with install. There are some very very large projects going up out there, especially in NYC.

    Our thought is that it's critical for every project underway be able to find and buy increased window performance no matter what their budget requirements. If every dollar being spent purchased a better window at the same price, then we would be moving towards a more efficient future much quicker. Finding and understanding the window options out there is the only barrier to this.

    Companies like Prossimo and Fentrend are making this happen:)


  5. Natur Haus | | #5

    Passiv, but not very sustainable
    One might wonder how "green" it is to truck windows in from Poland or Germany instead of using our best national window manufacturers offerings. How long does it take for the slightly higher performing windows to become carbon neutral or pay for themselves. We might be surprised by the answer to these questions. This relates to the old adage, " Is buying local non organic lettuce from next door or buying organic lettuce from out of state more sustainable" ?

    1. VT_Guy | | #12

      It is now 2021 and the question still is, why don’t Andersen, Marvin, Pella, etc. simply start making and selling high performance European-style windows in the US? Could it be that they don’t have to because they are allowed to engage monopolistic practices that have absolutely nothing to do with “green” or “passiv” but a lot to do with “bull”.

  6. STEPHEN SHEEHY | | #6

    reply to Matthew
    Sending a full container of windows by ship from Europe is pretty green. Trucking them from port to final destination probably uses more fossil fuel than the trip across the ocean. Trucking windows from a thousand miles from Midwest factory to NYC may very well be less "green" than shipping them four thousand miles.

    About a year and a half ago, I was looking at windows for my new house. I couldn't find anything from a US company comparable to the Intus windows I ended up buying. They were considerably more than slightly higher performing than anything I could get from Marvin, Anderson, etc. and the price was compelling. I would have much preferred to buy domestic windows.

  7. ben_prossimo | | #7

    Domestic vs. Import
    I had the same experience as Stephen on my house (Yaro windows for us). There just weren't any options domestically that could compare with the features and performance for the price.

    When I went to Europe to research suppliers for my business, I saw an amazingly robust, technologically advanced and super competitive industry that really puts us to shame over here. Even in the poorest countries of Eastern Europe, average consumers are acutely aware of their windows' profile depth, number of chambers, Uf, Uw, hardware brand, glass packet specs, etc...

    Replicating that model requires a wholescale revolution on our part in North America. Not to mention the archaic system of markups that exists in the building materials market that badly inflates prices. We need disruption! It's the only way to get people building radically better, as quickly and widespread as possible. Who's with me?

  8. ben_prossimo | | #8

    Shipping Issues
    Hi All,

    I just got a question to my email that I thought I'd clarify here.

    The square footage price is real. BUT, shipping is not included.

    Currently we are exploring different options to reduce shipping costs.

    Our goal is to make every project happen! So please contact us and we will do what we can!



  9. Expert Member

    Who is the warranty through? Do you deal with it or the European manufacturers?

  10. good4utoo | | #10

    Ventana USA
    What is the feedback on Ventana USA?
    These UPVC windows and doors are made in Pennsylvania, USA.
    But owned by German company Veka.
    Has anyone used these for a passive house or net zero house ?

  11. ben_prossimo | | #11

    Hi Malcolm,

    We service the warranty directly.



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