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Green Building News

New Window Certified by Both Passivhaus Groups

The ‘Zola No Compromise’ window is the first to win certification from both the Passivhaus Institut and the Passive House Institute U.S.

The Zola No Compromise window is available with triple or quadruple glazing. The windows can be ordered in sizes up to 8 feet wide and 10 feet high.
Image Credit: Zola Windows

A high-performance window from Colorado-based Zola Windows is the first to be certified by both the Passivhaus Institut in Germany and the Passive House Institute U.S., according to Energy Design Update.

The Zola No Compromise window is available with both three- and four-pane glazing and R-values up to 15. Fixed windows can be ordered in sizes up to 10 feet high and 8 feet wide; tilt-and-turn windows come in sizes up to 5 feet wide and 9 feet high.

Window frames are made of wood, with exterior surfaces protected by powder-coated aluminum cladding. Integrated insect screens also are available.

Zola, based in Steamboat Springs, Colorado, manufactures the windows in Poland.

Company Vice President Florian Speier said that in a project with a mix of window types, including tilt-and-turn, fixed and an entrance door, windows would probably cost about $60 to $80 per square foot. More complicated windows incorporating muntin bars or arches would be more expensive.

Speier said the production lead time is nine weeks. Shipping is an additional three weeks to the east coast and up to six weeks to the west coast.

For more information on Zola windows, see New Green Building Products — June 2013.


  1. Peter L | | #1

    Quadruple Pane!
    I never even knew such a thing existed. Wow! Quadruple pane windows! At $60-$80 per square foot of window area, that will be quite a lengthy time period before one sees a ROI in terms of energy savings. I wonder if those costs include shipping from Europe or is that additional?

  2. GBA Editor
    Scott Gibson | | #2

    Do prices include shipping?
    Zola says that would depend on the size of the order: A $20,000 order would not include shipping, while an order of $70,000 or $80,000 would.

  3. Peter L | | #3

    Well, I hope they would include shipping on a $80k order. That's what some people pay for their entire home. I'm all for energy conservation and building green homes but at these prices it's reserved for the 1% of the population who have a lot of money. It gives "being green" a whole new meaning....

  4. Flitch Plate | | #4

    oh yea baby!
    Once more we see that Green is the New Gold

  5. Aj Builder, Upstate NY Zone 6a | | #5

    $80,000 here only buys a
    $80,000 here only buys a double wide trailer on a rented lot.

    Before carpentry starts, it's easy to be at $80,000 here, which would be

    rough grade
    water catching swales, dry-wells
    electric service

  6. TJ Elder | | #6

    Kazama Windows
    Jin, what type of frames are you planning to use?

  7. Jin Kazama | | #7

    hard to justify ...
    60$+sq ft is pretty hard to justify unless you have only a few relatively small windows and wish to have high end performance...still ..

    A 20ft container from most european port to Montreal or NY port doesn't cost that much ...3-5000$ including fees .. but if your window order is for a total of 20 000$ additional 4-5000$ brings the cost per SQFT up quite rapidly.

    Some designers of PH wish to use only PH certified windows , but if understood it right
    a PH building does not have to use PH certified windows if the used windows have the appropriate performance ( evaluated on a few key points .. ) would have to check that

    But as Fitch pointed out, green for rich is no necessary green and becomes only flash .

    Green is supposed to be for the planet , not for the ego.

    I am currently working on a window design that would be modular and made here in Canada,
    and i am trying to make it so it could even be sold/shipped knocked down without any glazings,
    installer/reseller could source local glazings to prevent extensive transport fees/energy.
    And i hope to be able to meet PH criteria or be very close in performance, at an affordable cost
    for "real green" designers/home builders.

    Am i on the right track? another new window product ???
    maybe not, but i need the windows for my future projects anyhow,
    so instead of designing for myself only, why not resell it for others to use??
    ( i do not wish to pay 50-80$ SQ FT for every project i will be building, that is why i am investing in a simple window product line )

  8. Jin Kazama | | #8

    I plan to use aluminum frames with probably a double thermal brake in polyamide.

    I planted a few rules that i wish to follow, and aluminum is the only material that meets my rules
    when used as exterior cladding.

    Durability of window framing is very important because having to replace it breaks the efficiency of the design.

    One could probably use its own wood interior parts if wanted though,
    i wil try and plan so wood interior section could be attached somehow.

    The frames will be somewhat bulky to achieve correct performance,
    but the "feeling" can be attenuated with a hidden frame interior installation.

    And i am also trying to design it so the same frame can be used with a wider range of glazing width, instead of using different stops for every 1-2mm steps of glazings.
    ( will probably feature an adjustable section either via hadwares or spacers)

    the hole point is to bring parts cost and investment down , so the selling price point can be lower.

    Should be fun :)

  9. GBA Editor
    Martin Holladay | | #9

    Response to Kevin Dickson
    Thanks for the illuminating and useful calculations.

    Readers who are interested in this topic may want to see Study Shows That Expensive Windows Yield Meager Energy Returns.

  10. Jin Kazama | | #10

    Kevin and Martin ..
    Again, it is all relative to climate and energy costs.

    In most northern europe where energy can be costly and where residents usually accept longer ROI
    ( usefull life and ROI on windows are usually calculated @ 40 years there )

    Higher cost windows make sense, as was pointed out many times in the past by different studies.

    Then, i do not believe that your 12$/sqft windows will last as long as premium windows,
    this needs to be factored in the price also. Equivalent quality products should be compared, not a cheaply made window VS a premium quality one. Efficiency is not the only criteria in a product.

    Then, If you take rougher climates such as north east NA zone 6-7 or even zone 8 .
    COP of minis goes down to 2.0 ~ 2.5
    HDD from 8500 to 11 000F
    PV production goes down to 0.8~1.1KWh / KW installed.
    Not as much as incentives in many of the northern states and provinces.

    I do not agree for 60$/sqft + windows ,
    BUT, it does make more sense to look for higher efficient windows.

    Then again, regular efficient house VS PH house is very different.
    A PH house needs to meet a specific energy criteria, and balance between SHG and U value of windows is more critical . This is a designer/owner choice.

    Conclusion : you conlusion is revelant only to a specific situation.

    still need to push for the " it depends! " answer ..

  11. GBA Editor
    Martin Holladay | | #11

    Response to Jin Kazana
    Your factor adjustments are roughly as follows:
    Windows last 75% as long: 0.75
    COP of heat pump is lower: 0.66
    HDD adjustment: maybe 0.77
    PV output adjustment: 0.5

    So, Kevin calculated that an investment in PV yields 8 times more than a window upgrade.
    Taking 8 as our starting point, we get:
    8 x 0.75 x 0.66 x 0.77 x 0.5 = 1.5

    So, in your worst-case (and highly pessimistic) scenario, an investment in PV yields 1.5 times as much as a window upgrade.

  12. Kevin Dickson, MSME | | #12

    Just How Bad is the ROI of Premium Windows?

    5,000 Degree-days per year
    U value of Home Depot Energy Star vinyl window = 0.33
    U value of premium window = 0.1
    $0.13 per kwh energy cost
    Minisplit COP = 3.0
    Average cost of HD window = $12/ft2
    Average cost of premium window = $60/ft2
    Total Square footage of windows for the house - 300ft2
    PV solar system cost = $4.00/KW
    Solar system generates 1900 kwh/yr per KW (in Denver)

    Total cost difference = $14,400 HD vs. premium windows
    Yearly savings due to premium windows = $105
    Yearly savings of $14,400 invested in photovoltaics = $888 before any tax credits or other incentives

    Conclusion: A dollar invested in PV is eight times better than a dollar invested in great windows

  13. Jin Kazama | | #13

    I guess we could guesstimate as so .. le'ts assume from 1.5 to 2.5 to 1 .

    Could probably factor 2 to 1 for the life but still ..

    But, every new building requires windows.
    And that is somewhat different than going for window replacement.

    Then, if you take my local situation, Hydro Quebec does not cash back any overproduction of energy, so PV potential is limited to total usage per year or less. ( annual KWh credits )

    That said, if you are going for a very efficient house desing or up to PH,
    there might not be too large of a possible PV array to install ( example a local small house with sub 1000$/year of energy bills would require no more than ~7.5KW of installed PV )

    With current falling prices of PV , in the near future 7.5KW might cost 10 000$ installed,
    so that budget will be fixed.

    I agree that in most markets where energy costs are higher than 0.12~0.14$/kwh , PV has greater value than windows, but you still need windows on a house, but do not necessairly need PV.

    What is the average area of windows per house in usa ?

  14. Jin Kazama | | #14

    about COP of minis ...
    It is easy to use their ratings SHP etc..
    but in reality, in cold climate, you almost always need backup heating to cover those sub -25c nights,
    and although i do not have any numbers to show, in a non PH house, if we take last winter as example, the resistance backup heating was on for everyone very often, almost every jan/feb nights.

    This further brings the COP of the total heating system down toward 1:1 .
    It would be very hard to estimate and a case by case, but when the temp is -30c from 11pm to 6am,
    it is then that you need the most heating and where the heat pump fails to deliver
    ( unless you are sleeping in an insulation castle with very high internal mass and SHG to help through the nights )

  15. Jin Kazama | | #15

    Kevin :
    I was intrigued by the price of the HD JW window, so i looked at it tonight.
    It sure offers some value for low budget buildings, that i give.
    Lifetime wrranty at that price? nice.

    They seem to have similarly efficient and cheap double-hung also.
    But that's it.

    No fixed windows, no cheap casement ( casements go up to 30$/sq ft for the similar type/performance )

    So In your comparison, you've used a "special" product that although is available at that price point, it is also something i do not believe all would accept to use in their house .
    I do not like sliders at all, neither do i enjoy double-hung.
    Some might like those.

    And then, those window pricing are for mass production sizes, that severely limits choices to a few available sizes.

    On the other side, i've purchased large amounts of high performance canadian fiber windows
    for 30-40$ sq/ft average ( let's assume 60% fixed , rest were casements and awnings )

    And the fixed units had almost "PH" performance ( triple pane argon low 2 and foam filled frame).

    To make a fair comparison of cost here,
    20$/sq ft would be a much better pricing for base grade double pane low-e windows for a complete house ;

    and 40-50$ could be used for the performance up to PH style windows.

    This would reduce your calcs from a factor of 2.5 already.

    Again all this is climate related, but as soon as you'd hit zone 6 i am pretty sure that the ROI would look much better now .

    Pushed a few buttons on my calculator this evening,

    using the following numbers :

    Double clear glazing = 2.8U .75SHG
    Double argon low-e = 1.64U .7SHG
    Triple argon low-e = 1.07U .5SHG

    only considering glazings, vertical direct solar south orientation

    for my location ( east of Montreal, QC )

    SHG minus heat loss per m2
    ( no shading factor , pure comparison , insolation numbers taken from PV MAPS at nrcan ,
    4500HDD @20c )

    double clear glazing = +100KWh
    Double arg low-e = +203KWh
    Tripple arg low-e = +180KWh

    still per m2

    only 80KWh of gain on a south facing window going from double clear cheap glazing up to performance triples .. ( again glazings only )

    Heat loss alone

    DB CL = 300KWh
    DB AR L-E = 177KWh
    TR AR L-E = 115KWh
    per m2

    not that much still

    i'll try and see how much difference the frames from a cheap vynil windows @ 12-20$/sqft
    would add to the difference from rightly done frames.

    300sqft ..average size of window 12sqft me around 350ft of frames.

    Do not take me too seriously here, i learn by doing this kind of stuff,
    and doing it here pushes me to learn and question myself even more!!! :)
    And its fun!! :)

  16. GBA Editor
    Scott Gibson | | #16

    Updated shipping information
    Zola Vice President Florian Speier has offered updated information on shipping charges. In an email to GBA, he said the prices he quoted earlier do not include shipping. The company charges a flat rate of $4800 to ship a container of windows to the lower 48 in the U.S. One container typically fits projects up to $120,000 in value, Speier said. Zola's minimum order is $25,000.

  17. Kevin Dickson, MSME | | #17

    The Power of Mass Production (and high order quantity)

    Your estimate of $20/ft2 of Home Depot Jeld-Wen window is right on for custom-sized casements (straight from my special order receipt). A custom fixed window of that same size (36"x54") is $16.90/ft2. Smaller window prices get higher, of course.

    The window I linked to above, is a high volume, on-the-shelf slider that costs only $8.37/ft2.

    Any home designer should seriously consider sticking with only the high volume units if cost is important. I'm pretty sure that a U value of 0.33 won't cause comfort issues as long as you don't create a "wall of glass".

    I've inspected lots of 20 year old cheap vinyl windows, and none of the frames needed replacing. The glazing unit, of course, is easy to replace if needed.

    With in-stock windows, you can return for a full refund any window that was mis-ordered, and they can be delivered for about $100 on the exact day they are needed.


    1. We haven't compared the infiltration rates.
    2. Home Depot's "on-the-shelf" sizes and specs are changing all the time. They might discontinue a window that you chose last year.

  18. Karl Miller | | #18

    Zola Windows
    Europeans use Zola windows (or other European brands of windows and doors like them) because Europeans know they simply can't afford to use American type windows which do little more than stop the wind from blowing unhindered through the house. Buy the windows or buy the coal and oil.

    We used them in our new house last year and the difference in quality and comfort is astonishing. We have been through one cruel New England winter and are very happy with our choice. Zola also has great follow-up service.

    There are lots of places to save material costs to help defray the expense. It just doesn't make sense to insulate a house well and then install virtual holes in the walls.

  19. Jin Kazama | | #19

    Kevin: yes i guessed that the 20$/sq ft was going to be within what is usually paid for good projects.

    The HD window you linked is of course unbeatable. I would even dare to recommend it to anyone with low budget. Still , would you install 25 or so of those in your personal house ?
    Would you buy a house with 25 HD JW sliders ??

    Karl Miller: mmm ...window manufacturers even in usa/canada pass infiltration tests and other tests by their respective associations ... there are many high quality windows available in north america
    There used to be no incentive to work on higher performing windows in the past because
    of the low energy prices VS europe.
    We are only late to it.
    same goes with insulation
    it is all a question of economical value to the general public
    and the buyers drive the market for products

    Scott : so their minimum order is 25K$ including the shipping or + the 4800$ of shipping ?

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