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few questions on window selections

Scouting5867 | Posted in General Questions on

I need 21 windows for my new house build in Zone 5 New Hampshire

Getting some quotes from a few companies and need some education to help me make a smart compromise between performance and budget

I read the PGH book and they indicated double-hung windows will be the highest U-value, with casement and tilt/turn being the better options.

I did get one double hung quote from Alpen, but the price was very high.  So I guess it’s possible to get high-performance in a double-hung window only if cost is not a limitation?

The other quotes are for casement and European tilt/turn windows.  U-value are generally 0.15 to 0.20.  The PGH book suggested 0.20 as the “good enough”, is that still a reasonable economic rule of thumb?  Is there some way to estimate the point of diminishing returns, based on estimated wall assembly R-value and air-tightness?

I’m seeing different frame materials from different suppliers: vinyl, fiberglass, aluminum.  Haven’t seen any wood frames.  What are the pros and cons of each frame material?

Has anyone ordered from Doorwin?  They ship freight directly from China.  The price is very appealing.  European-style tilt&turn windows, triple-pane glass, NFRC U-value 0.23, for about half the price of stateside vendors.
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  1. Expert Member
    Michael Maines | | #1

    Scouting, I wrote that chapter of the book and just placed an order for a triple-glazed, wood-framed, fiberglass-clad triple-glazed double-hung for my own house. You're right that we recommend swinging windows when they will work, since they maintain air tightness better long-term due to how they close against their seals rather than having enough slop for the sashes to slide. But sometimes double hungs (or other sliding windows) are the right choice for the project, such as on my 1830 farmhouse.

    On p.138 we share Building Science Corp's recommended values; they suggest U-0.24 is good for climate zone 5. On p.140 we share our recommended values, including U-0.22 for climate zone 5. Somewhere around 0.22 to 0.24 is a good target, but if you perform energy monitoring and depending on initial costs vs operating costs, you may choose to go a bit higher or lower, especially when balancing against the other important performance metrics of SHGC, VT, CR and DP.

    Coincidentally, tomorrow evening, a few GBA regulars will be doing a webinar on windows, including Greg Novak, who has shared mountains of glazing information here under the screen name Oberon; Josh Saligner, a design/build contractor in Oregon, a Marvin rep and me. Considering the lineup, I don't expect to say much!

  2. walta100 | | #2

    You are facing what maybe the single hardest and most expensive choice in this project.

    What is most important keeping the construction costs down at the expense lower comfort and higher operating costs in the future?

    When you select a U value for your windows you are picking the maximum humidity for the heating season. When you select a higher U value the glass will have a lower surface temp that temp becomes the highest dew point possible in the house. That dew point combined with the thermostat setting set the relative humidity in the home. For the best comfort pick the lowest U value.

    If this choice is more about return on investment and lower operating costs. No offence to the author but the recommendations for U values are based on a set of assumptions about the weather, fuel costs, window upgrade prices, a guess at inflation and interest rates/opportunity cost. Every one of the variables in this equation are in flux and different for each builder. I say the only way to maximize your return on your investment is to make your choices based on the facts of your build. There is a free computer program that lets you enter your data about your build and show you the winning choice from a range of U values at different price points. My guess is it takes about 20 hours to do the training and enter the data.

    BEopt software

    BEopt training videos


  3. xbcornwellco | | #3

    I work at Alpen High Performance Products. Happy to hear you got a quote from us, appreciate the interest, greatly! 20 is a great starting point; go lower as money and the interest of being more energy efficient allows. There's nothing wrong with being in that ballpark, slightly over or under.

    If you're building new construction, a HERS rating (energy modeling) will most likely be required in most areas. I used EnergyLogic for my own home. Give them the #'s (insulation, air tightness, window u-value, etc.) and ask them to play around/adjust the window u-factor value to see the overall savings/efficiency/etc over the baseline. This is about as simple as it gets if you're looking for something super easy to understand. Each build is unique, modeling is the best way to answer your questions in more detail.

    I love fiberglass, but my next favorite is fiberglass reinforced uPVC (not vinyl or simply uPVC). I've seen too many aluminum and wood corner samples that make me question longevity. Of course, there's some good and bad as with anything. Some wood/alum windows are darn beautiful and be quite well made. The biggest pro for NON-wood/alum frames, is the lack of movement. Stresses on edges, seals/critical areas greatly affect durability. There are studies on these things that I found rather to be fascinating. I started to discover them when I got into nerdy ThinGlass data.

    One of our dealers said he'd have a panic attack every time a shipping container of European/overseas windows would arrive. Sort of why he stopped selling those and switched to American brands. Too much damage, and can you imagine the difficult repairing units + lead times + shipping times? Non-local or even US support, nightmare.. I could go on about overseas vendors selling windows to Americans with interior rated films on the exterior.. And these films work great overseas but not for NA's harsher climates, and thus they end up peeling, flaking, etc. That's just one of many things. I could go on and on about the claimed performance #'s and the realities..

    Best of luck on your search. I know windows can be a tough expensive to bear. But they are one of the most important components to any high performance build these days.

    1. andyfrog | | #4

      "Non-local or even US support, nightmare.."

      Any update on this case: ?

      1. xbcornwellco | | #10

        Asking our service and warranty team now.

        Perhaps they weren't installed plumb, level, or square or properly adjusted? Perhaps Alpen made a mistake in the construction? Our windows and doors are made by humans after all. Things happen, but I'll look into it because these things do matter. We have a rockstar team of service/warranty/engineering folks working here at Alpen.

        Update: Turns out this case was installation error (Not at any fault of Alpen's). Our service team has VERY extensive logs and takes customer service VERY serious. We use that info to make improvements.

        "The Swing Door sashes had to be completely replaced because of how poorly the Doors were installed and maintained throughout the project by the Builder. The replacement sashes for the front single swing door and the French side door, were chargeable to the Builder due to the poor installation, he did not respond to the request for quite some time, which delayed the resolution."

        "Simple adjustment would have fixed the issue, but the homeowner refused to do anything or learn anything of how to adjust the windows, themselves. The instructions were communicated multiple times. The builder also did nothing to adjust any window or door after they were installed. Alpen HPP provided 5-6 “good will” service visits. This is a brand new house! Just expecting everything to work flawlessly, immediately without adjustment, and clearly documented/communicated installation problems is a very unreasonable expectation."

        This door frame is installed “twisted” by ¼” inch. Yes the door sash is “bowed” only due to the frame being installed racked/twisted ¼”.
        Door Frame is not installed “Plumb”.
        The door frame is not installed “thru-frame” at the hinge locations!
        The door sash would not close due to poor installation. The bottom lock pin was hitting the frame and causing the door sash to “bow” away from the sill. Poor installation and zero adjustment was performed on this door. It sat for 6 months unadjusted and not closing properly just being jammed shut as hard as possible.

        In regards to the windows: PH+ Weather Stripping was “short” in the bottom Sills of the Common Mull / T-Mull window unit. Alpen immediately corrected this with an in-person site visit. Even then, the house still had blow door scores well below 0.50 ACH.

        Alpen makes high end windows; and our service team is wonderful. Always two sides to the story.

    2. Expert Member
      Deleted | | #6


  4. [email protected] | | #5

    "European-style tilt&turn windows, triple-pane glass, NFRC U-value 0.23, for about half the price of stateside vendors."

    Not knocking the U.23 as a performance value, because U.23 is a great value for a high performance dual pane, but not for a triple T/T unit. Seeing that U factor associated with a triple-pane, tilt/turn window, my first thought is "what did they do wrong"? For a triple T/T, I would expect at least a U.19, with a U.16 or better as routine.

    Considering window material, if I am looking for a modern clean look that resembles metal windows but with less maintenance and much better energy performance than a metal window, I am going to look first at fiberglass. Fiberglass windows tend to be more versatile and are often the aesthetic choice when compared with vinyl and they require less maintenance than wood.

    If I want a window with a more traditional look and feel, a window that radiates warmth, then I am going to look first at wood because wood still offers the best aesthetic in that role.

    But if I want maximum energy performance, often at a more reasonable price-point than the other options I am going to start with vinyl because generally speaking vinyl windows offer superior energy performance numbers when compared with wood or fiberglass.

    And keeping things less simple, there are also hybrids such as Fibrex, which is an Andersen-patented combination of vinyl and wood fiber that is the material used for Renewal and 100 series windows, or Glastra, a fiberglass hybrid used by Kolbe for their Forgent line.

    As you consider the window sash/frame material, always keep in mind that the quality of the company that manufactures the window is much more important than the material that they use. Good companies make good windows and bad companies make bad windows no matter the material that they use to manufacture their product.

    Now consider a sample wall that's 30'x8' (240 sqft), with 2x6 studs, 24 OC, and R 19 fluffy stuff basic insulation. Actual wall performance including sheathing, drywall, and such should be about R 17 best case or U.06 (I am rounding numbers a bit for simplicity).

    So what happens if we install three different 48 sqft windows with different U factors in this wall?
    Window with U.15 will lower overall wall performance to U.08 or R 13
    Window with U.25 will lower overall wall performance to U.1 or R 10
    Window with U.35 will lower overall wall performance to U.125 or R 8

    Disclaimer: obviously these are very basic numbers that don't take into account air leakage, SHGC, shading, direction the windows are facing, etc., but assuming I did the math right, they do help illustrate why a better performing window might be a good idea.

    1. tdbaugha | | #8

      Less maintenance than a metal window? What kind of maintenance does a metal window need? We’re about to place an order for thermally broken & insulated aluminum windows. One of the biggest reasons we chose aluminum over wood was the durability and maintenance factors.

    2. tdbaugha | | #11

      "resembles metal windows but with less maintenance and much better energy performance than a metal window, I am going to look first at fiberglass" What maintenance issues are there with metal windows? We're about to place an order for thermally broken & insulated aluminum windows and one major factor for choosing aluminum was for its durability.

      Also, do you happen to know or can you ask which cardinal plant(s) are making large triple pane IGU's now? I was just told by my local showroom that Kolbe is taking over the entire offering of Reynaers windows for US manufacturing. My only issue with Kolbe in the past was the lack of larger triple pane IGUs.

      1. [email protected] | | #14

        Sorry, that was supposed to read "...less maintenance than wood...."

        There are currently two Cardinal IG plants that I am aware of that are making large (up to 142x94) triples, one of them is Kolbe's direct supplier.

        1. tdbaugha | | #23

          Cool. Sent my window and door schedule to the dealer today for a Kolbe quote. Thanks

          1. [email protected] | | #24

            You're welcome!

  5. nynick | | #7

    I chose Alpen Tilt & Turn for the renovation of my old New England home that currently has old, single pane, double hung windows. They were about 20% higher than Marvin Elevate, double glazed.

    To mimic double hung, Alpen installs muntins inside the windows with a spacer bar halfway up. We specified the 6 over 6 look. To reduce costs, I specified many non-operable units and also quite a few Hopper type windows. We also ordered some picture windows.

    I just placed the order and am really excited to see how good they are. It's a LOT of money but hopefully worth it.

  6. orange_cat | | #9

    So to your point of diminishing return and economic value - I have recently upon the advice of this forum calculated heating load and cooling load using this free tool:

    It is a fantastic tool and I only regret not doing it when ordering windows. You see, one of the inputs is the window u-values and SHGCs and output is heating/cooling load in BTU (which is fairly easy to convert into operating costs with a few assumptions).

    You can play with those inputs - u-values and such (I did it for the skylight as we were about to order one and had several choices) and it was illuminating to see the difference. You can fairly easily calculate the added annual cost from differences in heating loads/cooling loads depending on entered u-values (i have entered values for the windows we considered but not ordered and it was not that big).

    We have more than recommended 20% glazing so one way to keep the cost down was to keep many windows fixed - not openable - and only some strategic casements/sliding doors (which improves the energy performance too). We went with aluminum clad wood becauseof the design style (but also longevity was a factor).

    We only got quotes from Canadian suppliers - Marvin, Weathershield, Windsor, Loewen, and I am forgetting one more - they were all over the place (e.g. certain sizes were cheaper at one, others at another, where I almost was ready to order half of the windows from one supplier and the other half from the other - but did not as when I told them that they improved the pricing).

    As for chinese windows- many (most) north american suppliers have a history of failing gas-filled windows/performance issues few years down the line. I think they have improved the process. There may not be much recourse, but perhaps some warranty replacement? Vis-a-vis chinese supplier where there is not any. The cost advantage must be significant to make up for it. Plus people are skeptical about performance ratings even for north-american made windows, I would be even more so about any proclaimed chinese ratings unless they are from an independent lab.

    1. [email protected] | | #17

      "As for chinese windows- many (most) north american suppliers have a history of failing gas-filled windows/performance issues few years down the line."

      There are over 1200 window companies in North America, do you have data that suggests that most of them have a history of failing gas filled windows?

      "We only got quotes from Canadian suppliers - Marvin, Weathershield, Windsor, Loewen"

      Of the four, only Loewen is a Canadian company (near Winnipeg), while Marvin is in Minnesota, Weathershield is in Wisconsin, and Windsor is in Iowa.

      1. orange_cat | | #18

        I did not mean to step on any toes. I should have said "some" rather than "many(most)".

        But when researching the specific manufacturers mentioned (I only looked for the suppliers suggested to me by the architects and contractor), the history of failure seems to plague all of them. And these are relatively successful (if by no other metric than market share).

        Please note - I did not say Canadian "made" - I was careful enough to say Canadian supplied.

        There have been at least three class action law suits that come to mind with regard to windows failure - Hurd and MI Windows and Doors and Andersen, so this is not an imaginary problem . But I am sure the OP would love to hear recommendations for specific reliable brands brands (it is too late for me, but a few months ago I would have been very glad as well. Because it seems that long-term failure rates are basically not known, and one has to infer them from the level of complaints on the internet. Not the best source).

        1. [email protected] | | #19

          No worries, I was simply puzzled and was looking for clarification of what you were saying.

          Still not sure what you meant by Canadian supplied, do you mean sold into Canada directly by the manufacturer so to avoid the hassle of buying south of the border and then having to import?

          Canada does have a number of high quality window manufacturers, I would recommend several for folks in Canada who wanted to stay with local companies. Marvin is located only 6 miles from the Canadian border, so practically shouting distance.

          I don't know that there are many manufacturers in any industry that don't have occasional failures, it's really more about what the company does to deal with the failure that's important.

          Of the two companies that you mention, Hurd no longer exists, having been acquired by Sierra Pacific, and not many people would suggest that MI is exactly a high quality company.

          Still not sure where the idea of gas-filled failures is coming from though. There was a problem with argon loss resulting collapsed glass in IG units from the mid to late 1980's.

          Again not being critical, just curious what you might be referring to? If there is data on something that I am not familiar with, I would like to read up on it.

        2. orange_cat | | #21

          Thank you. What I mean by Canadian supplied is something that is locally available without having to import (whether from Europe or the US. Note, I do not mind an occasional trip south for something hard to find like specific bathtubs - done that - but windows is not something I am willing to deal with). So there is a local dealer and warranties (warranties are a big deal in case of direct imports to Canada by the way - anything imported even if it is something simple like a Miele washing machine - or a European made woodstove- warranties not honored if purchased in the US rather than here even though both are imports from Europe to begin with) and so on. I was also thinking that some Canadian brands may not be readily available in the US so indicated why these particular brands were in my choice set.

          Thank you for offering recommendations - unfortunately I did not discover this forum until recently and now it is too late for me to change my mind as the windows had just been installed. That horse had bolted. I wish I had a chance to ask questions before ordering windows. May be for the benefits of other readers mention some names anyway? I certainly learned by reading and asking only when truly desperate.

          The argon filled failures are more recent - I did not systematically look for it (I just looked for any problems) but these are much more recent than 1980s

          - there are more. Aside from complaints. I was looking only for specific brands and these things kept popping up. I resigned to "they must have fixed the problem" (noted in some general industry reviews who acknowledged past problems) but I am by no means convinced that thousands of dollars worth of windows installed in my new house are not going to fail in a similar manner. There just is not data out there that I was able to find one way or another. Just hope.

          1. [email protected] | | #25

            Thanks, I understand what you meant about Canadian supplied, makes sense.

            There really is no vast failure of argon filled windows, this really is a very well understood technology and manufacturers know how to control the process. Both Marvin and Andersen get their glass packages from Cardinal, the largest residential glass manufacturer in North America (arguably the world), and while not perfect, Cardinal does maintain a .2% failure rate at 20 years (actually at 30 years and counting, but warranty is for 20).

            Cardinal manufactures about 25,ooo,ooo IG units a year and if they had a problem it would be very well known.

            Neither of the the two court cases that you referenced concerned the IG or glass unit, and the Marvin was dismissed and AW was partially dismissed. There isn't a large company in the US that isn't sued many times a year, it's part of doing business in today's world, so I would tend to take litigation as a guide to quality with a huge grain of salt..

          2. orange_cat | | #26

            Thank you - that is comforting to hear.

  7. tim_william | | #12

    What is the reputation of Mathews Brothers Windows in Maine? I like the idea of locally produced windows from a carbon footprint standpoint.

    1. Expert Member
      Michael Maines | | #13

      I have a Mathews Bros double-glazed, double casement in my house that I installed about ten years ago. It seems to be in perfect condition. My only complaint is that on mornings after cool, clear nights, there is condensation on the exterior, due to night sky radiation--a sign that they are working properly!

      I have spec'd their triple-glazed windows on two projects, the second one currently under construction in Camden. They are very affordable and seem to be good quality, if not as beefy as a European-style window.

      1. tim_william | | #20

        I live in Camden, I should go test the windows when nobody is looking

        1. Expert Member
          Michael Maines | | #22

          The completed project is an ADU on Molyneaux road, and the project under construction is on Start Road. They are just about ready to install windows on the Start Road project if you want to stop by. Email me if you'd like addresses and an introduction to the builder--michael at michaelmaines dot com.

    2. [email protected] | | #16

      I agree with Michael Maines. Although I have never worked with Mathews directly, everything I have heard suggests that they offer a solid window system.

  8. Deleted | | #15


  9. Ian_plum | | #27

    Tim, did you end up going with the Mathews Brother's? Did you get in touch with anyone that had experience living with, or installing the windows?

    I'm up Route 1 from you a bit in Lamoine, in a breezy costal location.

    Currently debating Mathews Bro vs European style tilt turn flangeless windows. A few of our windows are large fixed lites, mulled to operable. Largest window has a total frame size of 8'wide by 4'tall. Curious if the Mathews brothers are still a good option when dealing with larger contemporary style design.

    Anyone else have experience with Mathews Bro triple pane?


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