What Windows Should I Buy?

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What Windows Should I Buy?

Designers and builders talk about their favorite window brands

Posted on Jun 1 2018 by Martin Holladay

Readers often post a simple question on our Q&A page: “What brand of window should I buy?” For an editor, it’s an exasperating question, because it’s unanswerable. The answer depends on a host of factors, including the buyer’s geographical location, performance expectations, budget, and personal sense of aesthetics.

Rather than attempting to answer the question, I decided to interview fourteen designers and builders of high-performance homes. I asked them, “What brand of window did you specify on recent high-performance projects — and why?”

Window basics

This article isn’t an introduction to high-performance windows. If you’re looking for that type of information, start with the following articles:

Background information on four window brands

It will be easier to understand some of the statements made below if readers have some basic background information on Intus Windows, Schüco Windows, Menck Windows, and Thermotech Fiberglass Windows.

Intus Windows are vinylCommon term for polyvinyl chloride (PVC). In chemistry, vinyl refers to a carbon-and-hydrogen group (H2C=CH–) that attaches to another functional group, such as chlorine (vinyl chloride) or acetate (vinyl acetate). windows manufactured in Lithuania. Until recently, Intus windows were popular with American builders looking for high-performance triple-glazed windows at an affordable price. This year, Intus announced that it will no longer sell windows to builders of single-family homes in the U.S., so fans of Intus windows have been looking for a substitute manufacturer.

Schüco is a German manufacturer of window extrusions, window hardware, and window fabrication machinery. The company sells components to window fabricators all over the world. Since different fabricators use Schüco components in different ways, there is no such thing as a “Schüco window.” Anyone who is considering buying a “Schüco window” should learn the name of the window fabricator and find out the name of the company who will provide warranty service.

Menck Windows are manufactured in Hamburg, Germany. A few years ago, the company announced plans to build a factory in Newport, Vermont, and hired U.S. representatives to solicit business at trade shows in New England. Menck cancelled its plans to build a Vermont factory, and instead opened a facility in Massachusetts. The Massachusetts factory was closed soon after it was built. Menck's withdrawal from New England left a bitter taste in the mouths of some U.S. customers.

Thermotech Fiberglass Windows were manufactured in Ottawa, Ontario. Many Thermotech customers reported serious problems with service. The company is no longer in business.

A tour around the country

I interviewed fourteen designers and builders in a variety of locations, including Washington, California, Texas, Virginia, Massachusetts, Maine, New Hampshire, Vermont, and Minnesota.

The designers and builders I spoke with mentioned 22 window brands: Accurate Dorwin, Alpen, Andersen, Cascadia, Duxton, Eurotek, FiberFrame (Comfort Line), Interstate, Loewen, Logic, Marvin, Mathews Brothers, Munster Joinery (Klearwall), Paradigm, Pazen EnerSign, Pella, Schüco, Tanner, Unilux, Wasco, Yaro, and Zola.

The interviews begin in Seattle. From Seattle, we’ll travel in a counter-clockwise direction around the country, ending up in Minnesota.

Seattle, Washington

Dan Whitmore, Seattle, Washington. Whitmore is a former builder now working as a consultant. “A builder I work with, a good pal, has been working with Alpen Windows for years. He uses Alpen because he has a good relationship with them, and they give good support — and the windows have good performance at a good price. He likes them. Their new Tyrol series has PVC frames.

“Another window I’ve used is Unilux. It’s a German company. It’s a good product with good support. The turnaround time is 12 to 14 weeks. It’s a stretch, but the plan is that while you are pouring your foundation, you should be getting your window order together. Unilux is a wood-clad triple-glazed window — aluminum and wood.

“Another project I’m working with is using Zola windows. They are wood-framed windows, aluminum-clad. We have a good relationship with Zola. A really good product and really good support.

“Generally if someone asks me who to start with when it comes to windows, I say, start with Unilux or Zola. They provide a high-end wood-clad product. I’ve gotten very good support from those two companies.

“A multifamily project I’m involved with is using Eurotek windows. It's a new company based in Los Angeles. The PVC extrusions are manufactured in Europe, but the windows are assembled in Los Angeles with Cardinal glass. Pricing was terrific. As far as I know, Eurotek is willing to bid on single-family projects.

“Another manufacturer worth considering is Cascadia Windows. They make fiberglass windows. I like them. They are great. But a lot of people want a wood interior.

“Be conscious of lead time. Be aware that triple glazing means these are all heavy windows, so you have to be ready for them. Make sure they are treated with care. Plan for delivery. When the truck shows up, you want to handle them as little as possible. With European products, you have to plan ahead. You usually have to order them early, and you end up having to store them.

“If you are ordering big tilt/turn windows, think about how they operate. You might enjoy a big piece of glass, but if you have an inswing window that is 4 feet wide, it’s inconvenient. People want to open it and stick their head out the window, but you have to think what will happen if the window sill is filled with knick-knacks and you try to open the window into the room. You need to know what you are getting into. If the window is big, you’re going to be leaving it on ‘tilt’ — you won’t be swinging it in. It’s a different usage pattern than Americans are used to.”

San Jose, California

Bronwyn Barry, San Jose, California. Barry is an architect. “When it comes to windows, I bounce around depending on the project. I have a stable of vendors or brands that I get quotes from. My favorite window is still the Pazen EnerSign. The windows are still probably the best windows on the Passivhaus market. The biggest barrier to using them is the support network — getting them delivered and any follow-up issues — so I have been loath to spec them. You want a robust support infrastructure to reliably carry a product. Windows are complicated. If you think that windows are simple, you are being naïve and you haven’t done your homework.

“European windows are generally more robust. They’re built more solidly, and hardware is more reliable. That’s why the European windows make a lot of sense.

“I have been using Zola windows. It’s not an innovative profile, but they have the most amazing sales and technical support at that company, and that makes a huge difference. They provide excellent sales, delivery, and post-sales support. They understand what they are selling you and can answer very technical questions. If the salesperson can’t support you through the purchasing process, then you don’t have a viable window business.

“I really like the Alpen windows. Alpen has stepped up their game significantly — they have new profile offerings. My one hesitation is that their doors aren’t very good. And when you order windows, you generally order doors. Their doors are just barely passible in the California climate, and anywhere else they don’t perform very well.

“The other company that is doing great stuff is Cascadia. I really like their profile. I have requested a bid from them on a current project.

“I have used Intus before on projects with a tighter budget. I have always held my nose on PVC products, but I’m changing my opinion. They are affordable. But Intus is no longer supporting the residential single-family market.

“I like the Klearwall product. I will probably be using them in the near future.

“Another one is Tanner Windows in Minnesota. They used to do Optiwin. They know their stuff, and the product is good, but it’s usually a high price bracket. The price is usually out of my budget range.”

Dallas, Texas

Armando Cobo, Dallas, Texas. Cobo specializes in the construction of high-end zero-energy homes. “In Texas, I can’t justify the cost increment to go to triple glazing. I think double-glazed windows with the appropriate low-e coatingVery thin metallic coating on glass or plastic window glazing that reduces heat loss through the window; the coating emits less radiant energy (heat radiation), which makes it, in effect, reflective to that heat; boosts a window’s R-value and reduces its U-factor. is good enough. If I were building my own house, I would choose either Andersen or Pella. I think those two brands offer the best combination — the best window, best warranty, and best service, all combined. More and more of our homes, even high-end homes, are using vinyl windows instead of wood or aluminum-clad wood windows. In the fancier homes, they like to use wood windows, at least on the front of the house, and then they’ll use vinyl windows on the other three sides.

“I never cared for Marvin windows, because they have the corners of the flanges cut out. They send you a rubbery thing for the corners, to patch the flange, but it’s easy to lose the corner things. The window might be sitting around the site for a week, and the corner things get lost. So you worry about a water leak. Maybe the window is just as good — I don’t know. But I like a flange that goes around the corner.”

“There are a couple of small local manufacturers of vinyl windows, and they are really cheap windows. The windows can have a half-inch discrepancy from how the windows were ordered. There is no quality control. Some builders want to use those cheap vinyl windows, and I say ‘No. Please, no.’

“The main window manufacturers in the country, the top 10 or 12 window manufacturers, are all good. If one of my builders has a preference that depends on the service they get, the delivery, the warranty — those are good things to look for. Like I said, the top 12 window manufacturers are all good.”

Charlottesville, Virginia

John Semmelhack, Charlottesville, Virginia. Semmelhack is a certified Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. consultant. “I usually ask the clients to give me some direction on aesthetics and budget. We can get a very high-performance window in a vinyl frame for a good price, but not everybody likes a vinyl window. You can pay $25 a square foot for a window, or it could be $100 a square foot. If you are willing to accept a vinyl window, I might suggest Interstate windows from Pennsylvania. They offer triple glazing, and they have some options with a high solar heat gain coefficient(SHGC) The fraction of solar gain admitted through a window, expressed as a number between 0 and 1.. These windows have great performance specs.

“If you want a wood interior, the ones I know in the triple-pane realm are Zola windows. If you want a wood interior in double pane, there are some nice windows from Marvin, like the Marvin Integrity. For a triple-glazed window, I would suggest Munster Joinery (known in the U.S. as Klearwall). The windows have a hybrid frame — a wood interior and an aluminum exterior. These windows are more affordable than Zola. They are made in Ireland, however, so there are lead time issues and replacement glass issues. You can’t go to your local IGU manufacturer to get the right spacer and glass combination for a European window, because they don’t carry that here. In Europe, the IGUs are thicker.

“The Klearwall window might be the best balance between appearance and performance, since it has a wood interior and aluminum exterior, as well as very high performance.

“For a fiberglass window, we’ve had great experiences with Accurate Dorwin. The windows offer great performance. The price is high, but it’s not the highest.

“Recently we used some fiberglass windows from Fiberframe in Ohio. Nobody knows about them, but they offer triple glazing, and they are cheaper than Accurate Dorwin. They make their own frames. They do nice work — comparable to other fiberglass-framed windows. We used them on a portion of a multifamily project. It went smoothly, and there were no complaints from the general contractor.”

Chilmark, Massachusetts

John Abrams, Chilmark, Massachusetts. Abrams is the founder of the South Mountain Company on Martha’s Vineyard. “For projects where performance is the central criterion, we use Alpen windows. We don’t worry about the suspended plastic films — we think they have it mastered. We may be wrong, but we hope we’re right.

“If craft, quality, and performance are important, we tend to use Loewen windows. We almost always go with triple glazing and orientation-tuned glazing. We tend not to use Euro-style tilt/turn windows because we’re concerned about adequate ventilation and good screen systems.

“Service matters a lot. We get fabulous service with Loewen, but with Alpen it is a little more difficult. Both Alpen and Loewen generally have 8-week lead times, but of course the lead time varies. In the past, we have bought Alpen direct, but we are resolved to buy from Pinnacle in the future because we expect to get better service.”

Amherst, Massachusetts

Jesse Selman, Amherst, Massachusetts. Selman is an architect at Coldham and Hartman Architects. “I’d rather not endorse a type of window. When selecting a window, we look at service; cost; performance; the materials the windows are made of; aesthetics; client preference; and builder preference. An example of client preference might be the operation of the window; some clients won’t use a tilt/turn.

“We also take a look at the global supply chain. Where were the parts built? How long has the window company been around? We want to choose a window company that we know to be stable. Is this a company that has been around for less than a year, or more than 20 years? We want to know the answer to the question, ‘When the window breaks, who do I call?’ We want to avoid the Menck situation, which left people in a tricky spot.”

Portland, Maine

Dan Kolbert, Portland, Maine. “We usually buy triple-glazed windows with a PVC frame — whatever Steve Konstantino at Performance Building Supply is selling, or whatever Kris Brill at Pinnacle windows is selling. Steve used to sell Intus until Intus stopped selling to single-family projects, so now he sells Schüco. Kris has his Logic brand of windows. For renovation work or historic buildings, where triple glazing isn’t worth it, we’ll choose one of the usual brands — Marvin or Andersen. They are perfectly decent windows.

“Service is the critical issue. Marvin is always tweaking what they offer, changing their lines, but they offer very good service, so I don’t worry. I would definitely make sure that whoever you are buying from will stand behind the product. That’s critical.”

Another voice from Portland, Maine

Christopher Briley, Portland, Maine. Briley is an architect. “Recently we’ve used two brands: Intus and Logic from Pinnacle. We used Intus for the balance of economy and performance. For tilt/turns in the European style, these PVC windows are economical solutions.

“Lately we have been shying away from Intus. When there is a problem such as a broken pane, or a hardware problem — or even worse, if a window is the wrong size and you need a new window — it becomes a waiting game. They say 12 to 14 weeks, but it’s usually 16 weeks or more. Because of the wait time, if the window is the wrong size, sometimes the builder says, ‘Let’s just re-frame the rough opening.’ The turnaround time for service is really difficult. You are always dealing with unknowns. Are the windows on the way? No one knows. So we’ve been moving away from Intus.

“We shop around our window schedule, looking for a European-style tilt/turn, and we usually pick Logic, which is practically interchangeable with Intus. Logic is assembled in Pennsylvania, so turnaround time is much faster than with Intus. The price is comparable to Intus or less.

“For clients who want beautiful wood-clad aluminum windows with triple glazing, we are always shopping around like everyone else. We haven’t settled on a favorite. I was talking with Jesse Thompson, and he says that the Sierra Pacific rep has been visiting him, but I haven’t seen their windows yet.

“We did a veterinary clinic a while back, and the building was changing the air three times an hour. The energy model showed that the building envelopeExterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials. was a small dial to turn — the energy use depended on the efficiency of the equipment, not the envelope specs. There wasn’t much of a difference in performance between double glazing and triple glazing. The same is true with Passive House multifamily projects — in many cases, all you need is a good performing double-pane window. The windows have less of an impact on a multifamily project than they do on a single-family home, where triple pane makes more sense.”

Still another voice from Portland, Maine

Jesse Thompson, Portland, Maine. Thompson is an architect. “If you’re writing about window brands, you’ll need to provide a biannual update. The market is always changing. Remember the Thermotech era?

“There are at least three different market sectors when it comes to triple-glazed windows for homes in northern New England. The first sector is the ‘pretty good house’ — that is, the semi-affordable custom home, a home that costs about $175 a square foot. That market sector has moved very heavily to vinyl-framed European-style tilt/turns. These windows cost in the range of $40 to $50 a square foot. For that sector, we use Logic windows or Klearwall windows. Klearwall windows come from Ireland, so you have to think about the lead time.

“If the customer doesn’t want a vinyl tilt/turn window, we can get a Marvin Integrity with a wood interior for about the same price. But the performance is worse.

“The second sector is affordable housing or multifamily housing. We wish we could use fiberglass-framed windows for this sector, but we usually can’t, so this sector is usually choosing a triple-glazed vinyl casement window from Koltech, Paradigm, or Pella. I like the Koltech casements — they seem to have more vinyl in them than other brands. In our area, we’re still using triple-glazing for multifamily housing, although further south, in Connecticut, double-glazing can work for a multifamily project.

“The vinyl casement windows I’m talking about don’t perform as well as the Euro-style tilt/turn windows. The U-factorMeasure of the heat conducted through a given product or material—the number of British thermal units (Btus) of heat that move through a square foot of the material in one hour for every 1 degree Fahrenheit difference in temperature across the material (Btu/ft2°F hr). U-factor is the inverse of R-value. for the casement frames is .25, as opposed to .17 for the Euro tilt/turns. And the glass is a little thinner — usually only 1 1/8 inch instead of 1 3/8 inch.

“The third sector is what I call the ‘nice custom home,’ an expensive custom home that costs $250 a square foot and up. These people don’t worry about their energy bills, so we talk to them about condensation control, comfort, or ethical issues — not energy savings.

“With these customers, we usually expect to have windows with a wood interior. If it’s a traditional-style house with generous roof overhangs, we’ll usually choose casement or awning windows. That means Loewen, Marvin, or Sierra Pacific. Of those three, Loewen probably has the better performance, but Marvin has great service in our area. Sierra Pacific is trying to move into the New England market, but we haven’t used them yet. These windows will cost about $65 to $85 a square foot. The windows will perform worse than a Euro-style tilt/turn, but for these customers, that’s OK. They’re looking for style and options, not performance.

“If we’re building a nice custom home in a contemporary style — a house with smaller roof overhangs — we want a window that opens to the interior. That means we want tilt/turns. We’ll choose Zola or Klearwall windows with a wood interior. These windows will cost the same as the casement or awning windows from Loewen or Marvin, but they’ll perform better.

“I wish we had more options with fiberglass-framed products. We don’t use Accurate Dorwin or Duxton because those companies have limited service capacity in our region.

“On some projects, we’ve used Alpen windows. They offer a wood interior and good support. There are Heat Mirror questions, as always. If someone asks me about the durability of the suspended plastic film, I tell people that I’m a little nervous. The Germans don’t use a suspended plastic film in their IGUs. But we haven’t had any problems yet with Alpen windows.”

Palermo, Maine

Michael Maines, Palermo, Maine. “On one of the last projects we used Intus, but that option is now off the table. We may try Performance Building Supply's products next time — the windows with Schüco frames. I have used Logic windows. They are good windows — basically an Intus clone. The company imports the PVC extrusions, brings them to Pennsylvania. The windows are assembled in Pennsylvania with Cardinal glazing units.

“Marvin Integrity is a good a starter window. You can get the Integrity with either double or triple glazing. In some areas, the triple-glazed Integrity windows cost twice as much as double-glazed, but in other areas the upcharge is only about $20 a square foot.

“I like Loewen windows. They have been doing triple glazing forever, and I’m impressed with the windows. They have a Douglas fir interior.

“Sierra Pacific is a new kid on the block. The company bought the old Hurd factory in Wisconsin, and they have a factory out West too. They offer triple glazing. They have at least as many lines as Andersen, and they offer triple glazing on some of the lines.

“One other company I might consider is Yaro Windows. They are good guys and honest. They offer PVC and wood windows. I will be looking at them. Unlike other manufacturers, they want to do their own installation.”

Lancaster, New Hampshire

Ben Southworth, Lancaster, New Hampshire. Southworth is a builder. “We started out ten years ago using Thermotech and Fibertec windows. Canadian fiberglass windows were the best thing going at that time. We wanted triple glazing, and were shooting for the lowest U-factor and the highest SHGCSolar heat gain coefficient. The fraction of solar gain admitted through a window, expressed as a number between 0 and 1.. Those windows were decent. While the performance numbers were good, the service was not.

“We finally jumped ship on those guys, at about the time that the European invasion was happening. Performance Building Supply was close. Those guys were great. So we used Intus. It’s a pretty good window, but the long lead time was tricky and stressful. Using European windows meant relearning how to install a window. We were used to the American flange. We had to learn about tilt/turns, and how they interacted with the faucets in the kitchen.

“We had a series of deep energy retrofit projects where we ended up using Pella windows because of the profiles of the muntins. They offer true triple glazing. We wanted a window that would look like an old 9-over-6 window. That was expensive, but the Pella service was excellent. The service reminded me of the ’90s, back when we were using Marvin Integrity. The service was insanely good with Pella. The quotes were turned around really fast. I learned how good service could be.

“Sometimes historical stuff comes into play. We’re just finishing up an energy retrofit in Jackson, New Hampshire. A local carpenter suggested we use windows from Mathews Brothers in Maine. It looks like what a window used to look like in the old days. It looked to me like painted pine, but it was a vinyl trim kit. Mathews Brothers makes a Passive House window. The performance is not quite as good as a European PVC window — a Passive House window from Europe — but the Mathews Brothers windows came at a very reasonable cost — cheaper than buying a PVC window from Europe.

“Now that we are starting to have data on our buildings, we’re starting to realize that we can do a pretty good job with lower specs for our envelope. I spent the last five years trying to pare down our insulation package. If our 2,000-square-foot buildings are using between 1,000 and 3,000 kWh per year for heat, we’re looking at whether it is worth it to double the insulation in the roof. What will it get us? You get to the point where it is not worth it. If you are just looking for durability and comfort, and if you have enough room on your roof for PV, it’s worth talking about whether Passive House makes sense, or whether it just makes sense to aim for net zeroProducing as much energy on an annual basis as one consumes on site, usually with renewable energy sources such as photovoltaics or small-scale wind turbines. Calculating net-zero energy can be difficult, particularly in grid-tied renewable energy systems, because of transmission losses in power lines and other considerations..

“I’m realizing now that I’m not dogmatic. I’m willing to accept lower specs. I am willing these days to go with a lower solar heat coefficient. I’d give up high SHGC for lower U-values. Sometimes, though, I worry about low visible light transmission. We used some Paradigm triple-glazed windows, and I thought that the visible light transmission was low. That said, the lower visible light transmission didn't affect the experience in the homes we built. The windows didn't appear to let through less light than windows with double the VLT numbers.

“What I’m trying to say is that I don’t really have a go-to window right now. We’re doing a job in Littleton using Logic windows. They’re triple-glazed. It’s a decent window, but not as good as Intus. From what I’ve heard, the service is excellent. But the windows haven’t been delivered or installed yet. Turnaround time is four weeks, and that’s really handy. When we used to order Intus windows, they’d say, ‘We’ll get right on it — the windows will be there in 12 weeks.’ That’s really tough.

“I have considered using the triple-glazed Marvin Integrity unit. If you do that, you’re taking a hit on performance. The solar heat gain on it is pretty bad. But you get really good service, and everyone knows how to install it.”

Cornwall, Vermont

Jean Terwilliger, Cornwall, Vermont. Terwilliger is an architect. “At a couple of recent projects I have used triple-glazed tilt/turn windows from Yaro. They have a couple of features I like. I used them on my own house. There are some places where we wanted corner windows, and they have a nice corner unit. They also have a nice heavy-duty aluminum sill. The prices are reasonable.

“The windows are distributed by Yaro, but the windows have ‘Schüco’ written all over them. They have delivered on time, usually 10 to 12 weeks. They also offer an aluminum claddingMaterials used on the roof and walls to enclose a house, providing protection against weather. on the window. It’s a nice system. You can order any color you want. The cost is competitive with other PVC tilt/turn windows.

“For people who still like the look of double-hung windows, I have used the Pella 350 single-hung windows. They are pretty tight, and they are available with triple glazing, with a .20 U-factor.

“We have used the Marvin Integrity triple-glazed windows, and we appreciate Marvin’s service. But they don’t quite have the performance of the other options I mentioned.

“We are looking at Comfort Line windows out of Ohio, but we haven’t made a decision yet. I have spec’d Alpen for some jobs, but no one’s gone for Alpen yet.”

Duluth, Minnesota

Rachel Wagner, Duluth, Minnesota. Wagner is a designer. “Lately, our projects have used Duxton fiberglass windows. We have a dealer nearby, so they are fairly easy to get. I like insulated fiberglass frames.

“We are also looking at getting Accurate Dorwin windows from a dealer in the Twin Cities for our projects down there. We’ve used Accurate Dorwin in the past. Service matters, and service from Duxton has been a little bit inconsistent. That’s one of the reasons I’m thinking of renewing my relationship with Accurate Dorwin.

“I keep looking at some of the vinyl windows, especially Wasco windows from Wisconsin. It looks like a good product. But when it comes to PVC, I just can’t go there, because I have another option that is environmentally preferable.

“For a wood window, I prefer Loewen to Marvin, because Loewen uses Douglas fir that is sustainably harvested, and their standard triple glazing is a 1 3/8 inch thick IGU — the same thickness as the triple glazing that goes into a quality fiberglass window. Marvin still hasn’t committed to using the thicker glazing unit, so their U-factors are not quite as good. With Marvin, you have to ask for an upgrade to get the better nailing fin — you have to remember to order the upgrade, and it’s easy to forget. We have used some Marvin windows when clients want a Minnesota-made window. They offer a good turnaround time. But service from Marvin is inconsistent. Some builders don’t like the service from Marvin.”

Manufacturers' web sites

For more information on the window brands mentioned in this article, see:

Martin Holladay’s previous blog: “The California Model.”

Click here to follow Martin Holladay on Twitter.

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Image Credits:

  1. Image #1: Martin Holladay

Jun 3, 2018 8:12 PM ET

Canadian fiberglass windows
by Antonio Oliver

I was surprised that the Canadian fiberglass frame windows didn't make more of a showing. Did Thermotech sour opinions on the whole lot of them? Is their cost comparable to the European wood and vinyl frame manufacturers? What gives, Martin?

Jun 4, 2018 5:16 AM ET

Edited Jun 4, 2018 5:33 AM ET.

Response to Antonio Oliver
by Martin Holladay

All I did was interview people on this topic, so I don't really have an answer to your question.

If you re-read the piece, you'll notice that John Semmelhack had good things to say about Accurate Dorwin.

Jesse Thompson explained why he doesn't use Accurate Dorwin or Duxton.

Rachel Wagner explained that she has specified both Accurate Dorwin and Duxton, and mentioned her disappointment with Duxton service.

Jun 4, 2018 1:13 PM ET

Inline Fiberglass, anyone?
by Ethan T ; Climate Zone 5A ; ~6000HDD

PVC is a problematic material, and is on the Living Building Challenge Red List of toxic materials. I know the question of material toxicity is controversial here at GBA, but it should be a part of any "Green Building" conversation.

After my own exhaustive search for a high performance window not made of PVC that didn't break the budget, I found myself comparing Duxton, Inline, and Alpen.

I settled on Inline Fiberglass. Duxton doesn't ship out East, and Inline provides profiles to Alpen. I also found that Alpen was not using a true triple pane but rather a suspended film, which has a sordid history which I was not willing to experiment with.

Jun 6, 2018 7:41 AM ET

matthews brothers
by John Williams

im general, especially here in new england, im curious why there isn't more attention paid to matthews brothers? we're building in the white mountains and even at this stage of the game, im still reaching back out to vendors to get quotes (inline, alpen tyrol series, several other tilt and turns and euro-styles) and no one really touches MB in price, meaning many are 50% or more in cost, not even close.

also, if you look at MB's passive glass glazing option their NFRC numbers surpass, in many cases they surpass the others in an overall ufactor, but also maintaining decent VT & SHGC, that im looking for on my south and west windows, hugely important to me. its not even that MB's numbers are amazing on those two fronts, it's that many others have really low VT and or SHGC, relatively speaking. so as a "package" i find MB to surpass them.

also bears mentioning, we'll be installing solar and having a tight, double wall, liquid applied air barrier envelope, so im following the advice of a bit less into the windows, a bit more into the envelope and solar package.

so what gives? what am i missing about matthews bros that makes them less popular, to the point of rarely being mentioned in my window research here and elsewhere? because they seem to be a really good value , however subjective that statement might be... yet not many mentions around here especially given they're made very locally to anyone building in NE

i'm 90% committed to MB at this point (and likely driving my builder nuts as i'm sure he'd like this detail locked down by now) and trying to reassure myself i'm not overlooking the downside to MB or missing out on an "affordable" superior alternative.

as ive said before on this site, window shopping is far and away the least favorite part of my build.

Jun 6, 2018 8:00 AM ET

Edited Jun 6, 2018 8:04 AM ET.

Response to John Williams
by Martin Holladay

Thanks for your review of Mathews Brothers windows.

Q. "Why there isn't more attention paid to Mathews Brothers?"

A. I don't really have an answer to your question, except to say, "GBA is paying attention to Mathews Brothers."

For example, the article on this page includes a positive review of Mathews Brothers windows from Ben Southworth. For more information on Mathews Brothers windows, see the following GBA pages:

Starting point for affordable triple-glazed windows?

GBA Product Guide: Clara Starrett Vinyl Windows

Two Builders Will Share Top Connecticut Prize

Vinyl R5 windows (see Comment #1 from Ben Balcombe)

Net-Zero-Energy House in a Kit

One final point: I note that you misspelled "Mathews Brothers." The company spells "Mathews" with one T, not two. If you are performing a web search on the company, it helps to spell it right. That might explain why you concluded that GBA hasn't mentioned Mathews Brothers very much.

Jun 6, 2018 8:42 AM ET

Edited Jun 6, 2018 8:43 AM ET.

Mathews Brothers
by user-6974075

I'm exactly where John is. I'm an hour south but building a high performance house, 1850 sq ft and I'm perseverating over the windows. I've looked at them all and I'm so grateful for this recent discussion and opinions on the different brands. I'm going with either Wasco, Klearwall or Mathews Brothers. They're all pretty great price points for triple glazed. Klearwall seems to have the best specs with 2" thick windows but long lead time. Wasco has great specs but only comes in white and Mathews Brothers has good specs but max's out at 1 1/8" on the triple glazing. I'm not going with tilt and turn, just double hung.

I've read here that 1 1/2" is optimum. Any thoughts on window thickness?
Thanks, Mary

Jun 6, 2018 8:59 AM ET

Edited Jun 6, 2018 9:06 AM ET.

Response to Mary (Comment #6)
by Martin Holladay

Q. "Any thoughts on window thickness?"

A. Are you asking about the thickness of the window frame or the thickness of the glazing? Traditionally, most U.S. window manufacturers made window frames that are about 4.5 inches deep (so that the frame extends from the interior surface of the drywall to the exterior surface of the plywood sheathing, assuming the use of 2x4 studs with no exterior rigid foam).

If you are asking a question about glazing thickness, here is what I wrote on the topic for an article that was published in the October 2005 issue of Energy Design Update:

"The gaps between the panes of high-performance triple glazing units are filled with an inert gas, almost always argon. For argon-filled glazing units, the optimal space between glazing layers is ½ inch, resulting in a triple-glazing unit thickness of 1 3/8 to 1 1/2 inch. Because thicker glazing units can be difficult to integrate into manageable sashes, some window manufacturers ... promote triple glazing units as thin as ½ inch. Such thin-gapped glazing units perform better with krypton gas than with argon gas. However, since krypton costs more than argon, some window manufacturers only offer argon, even in their thin glazing units; caveat emptor.

"It is difficult to design a double-hung or slider window that accommodates full-thickness (1 3/8” or 1 1/2") triple glazing. Many manufacturers interested in window performance... prefer to stick with full-thickness triple glazing, and therefore offer triple glazing only for casement, awning, or fixed windows. Those looking for triple-glazed double-hungs have to settle for a compromise product with thin (½” or 1”) triple glazing."

Jun 6, 2018 11:31 AM ET

Edited Jun 6, 2018 11:32 AM ET.

by user-6870177

I would dearly love to see a graph of "U" vs. price for Energy Star windows. The lowest I have seen for a "U" value is about 0.123 = R 8.1; we bought regular Kolbe windows with U=.26 or R 3.85. Considering that the total for our windows was about $16K -- and that was with wood interiors, etc., I don't see the value. In contrast the non-window parts of the walls are R40.

If energy efficient building is going to be the standard, then these exotic over-the-top solutions have to be identified as over-the-top and unnecessary.

Mary Essary Hoyer, Salem, Iowa

Jun 6, 2018 11:34 AM ET

Response to Mary Essary Hoyer (Comment #8)
by Martin Holladay

To read an article that echoes some of your conclusions, see Study Shows That Expensive Windows Yield Meager Energy Returns.

Jun 6, 2018 11:45 AM ET

Los Angeles
by James

Hello, I'm in Los Angeles building an 1800 square foot home. I would like as close to net zero as possible. Do I need triple pane windows or is this overkill for Southern California? It seems this article is written more from a cold weather climate perspective. Southern California is more a cooling dominated climate.

I find the comment about Marvin windows interesting. I like their product but wonder if the quality lives up to the price.

Jun 6, 2018 11:50 AM ET

Response to User 6872033
by Martin Holladay

User 687 etc.,
First of all, can you tell us your name?

Q. "Do I need triple pane windows or is this overkill for Southern California?"

A. It's overkill. Stick with double-glazed windows with an Energy Star rating; note that Energy Star requirements vary by climate zone.

For more information, see How to Order Windows.

Jun 6, 2018 12:37 PM ET

Edited Jun 6, 2018 3:03 PM ET.

Accurate Dorwin ordered for NH zone 5/6 residential
by Darlene Rancourt

Our window bid structure included 7 brands. I was interested in fiberglass-only frames because fiberglass conducts the least energy loss and has among the greatest durability..

I was expecting Inline or Alpen to come out the other end, and I was excited about Cascadia's new line. I've had walls with less performance than Alpen! And I thought I loved tilt/turn, which is something that Inline even does with DOORS.

Due to radius shapes in our window schedule (via segmented fiberglass, to simulate curves), we discovered that many 'fiberglass' windows have 'composite' areas to achieve radii, so several brands went off the list. Nothing wrong necessarily with composite, but my durability goal calls for uniformity of material, handling, maintenance etc.

Ordering windows specific to your project involves a learning curve, even when you know what you are doing. Also, you may discover that you need a 'trim, modern' look patio door (as I did), or that your project benefits from a re-allocation of the glazing; for instance, two very tall casements become casement-over-awnings. Some companies just don't 'click' with you, don't educate or quickly respond perhaps - or, may not offer what you just discovered you wanted (sorry!). . . so a few more went off my list.

In general, you will need to watch out for and specify your performance measures and your Tempered Glass requirements (per your applicable code), yourself. I had to create and present a crosswalk to our inspector, in order to avoid the dreaded 'rules of thumb' so prevalent in construction code compliance/practice.

For our project, I would have been as pleased to use finalist Fibertec, but Accurate Dorwin edged them out for several reasons - ALL specific to my engineering temperament and project-specific needs.

For both of these companies, and for our window schedule, we found a jump to all-triple-pane was less than $2000 more, than for south-face-only.

We ordered all tri-pane.
Performance Specs (awning version) are:
The south face is SunGate400 with u .19, SHGC .39
All other exposures are SolarBan60 with U .17, SHGC .23
The fiberglass 'patio' doors are U .20, SHGC .14

We received the factory-applied options that we wanted: (aluminum) universal brickmould (including for radii), nail flanges, and 3/4" drywall returns (for our site-built (painted) wood jamb extensions). Oak veneer (mainly Red) is available for the interior, but we ordered white inside and out. The locksets and hardware were easily comparable-to-superior.

To achieve my end results, there were many reviews and explanations, in both directions. My Accurate Dorwin representative, Yuki Shiokawa, was top notch, responsive, and sent picture descriptions often.

The delivery experience was as-described, well-packaged, slightly ahead of schedule, and seemless. For our construction season and glazing needs, ours was a 10 week window from the deposit date.

The house stage is pre-mechanicals now; The building crew has about half of the windows from Accurate Dorwin installed and all is excellent at this point.

If anyone is interested, other glazing specs on the project are:
Sunroom (3 sides, N, E, and S exposures)
U 24 SHGC 27 folding doors
Cardinal 366, i89 dbl pane
By Solar Innovations Inc

Sunroom (E exposure)
U 29 SHGC 23 large roof skylight
SolarBan 90 dbl pane
by Sunspace Designs Inc

Commonwall separating Sunroom from Main house
U 21, SHGC 41 slider door and windows
Cardinal 272 i89 dbl pane
By Solar Innovations Inc

Yuki's pictures 003 half round brickmould ext. cap resized 003.jpg linear style door # 1 resized.jpg EnviroshakeInstallComplete.jpg Darlene Rancourt elevations.jpg
20180502_A400-ElevationsLetterSizeNoKey.pdf 588.44 KB

Jun 6, 2018 12:47 PM ET

Edited Jun 6, 2018 12:50 PM ET.

Response to Darlene Rancourt
by Martin Holladay

With that much glass on the south elevation, I'd be worried about overheating in March and April.

Once you've got the house built, report back and let us know whether the area of south glazing turned out right.


Darlene Rancourt south elevation.jpg

Jun 6, 2018 12:57 PM ET

Edited Jun 6, 2018 1:12 PM ET.

South Face Glazing - Accomodations
by Darlene Rancourt

Wow, thank you for noticing! With the heating season occupying most of the year, we decided to let in the sun's heat and compensate for it in the few summer months.

To your point about the shoulder of March and April, I do think we will have to learn which of our summer accommodations to utilize ~

We will have personal-zone minisplits, but the wall assembly is designed to 'live and dry' in both directions without counting on central air. Prevailing winds in this location come from the south.

The three foot overhang will protect the attic windows and some of the second floor, in the summer when the sun is 'high'. Blackout curtains are already planned for the second floor, so we will kick those in if we discover a need in the summer (master bedroom).

The first floor has awnings planned, of the sort that may remain 3' extended 24/7 (during summer). There is an adjustable-louver pergola in front of the south/sunroom (which also has a 2' overhang on three sides).

The walk out cellar south windows are 'protected' (ug!) by the deck above - we can only hope for good daylight!

In winter, when the sun is lower, we hope the SHGC will let in the heat, and the tri-pane will help to keep it in!

Cross-fingers, of course, as always . . .

Jun 6, 2018 1:25 PM ET

"...personal-zone minisplits..." is probably a mistake @ Darlene
by Dana Dorsett

The heating & cooling loads of individual rooms are usually well below the capacity of any ductless head even in code-min houses, and even more so in high performance houses. In multi-split systems (multiple heads, one compressor) the individual heads don't modulate (with a few exceptions), so in a high performance house you're guaranteed to short-cycle the ductless heads, and probably the compressor too. The result is a combination of lower comfort and lower efficiency.

This 3- level house is probably better served by three separate mini-duct mini-splits, each on it's own fully modulating compressor, not a multi-split.

This really requires a careful room by room, zone by zone load calculation & analysis, but the "ductless head per room" approach is almost never optimal, and usually costs more than a better optimized solution.

Jun 6, 2018 1:50 PM ET

Dettson Supreme with Alize heat pump?
by Darlene Rancourt

Dana, thank you (darnit, she said with a sigh). I 'hate' the idea of central cooling, and love the idea (over simplification here) of window units! So, in a modern house, I was going to use (multi zone) minisplits.

I did get a third party/independent J load, and I gave it to Dettson to look at their (modulating) Supreme (Electric) and those so-cool 'Smart Ducts'. The initial blush is as you said - three systems, and the heavier cooling load driving the cfm/duct design (and unit sizes probably).

The Sunroom was omitted entirely, probably because I heard nothing about zones. Round 2/review is coming up . . . and then, somehow, (THREE?) ventilation units (Dettson has that cool third wire and has been integrated, same ducts, with ventilation - albeit with a few return air adjustments) . . .

As for our lifestyle issue - we are used to zero central and window units (that bleed out to larger semi-controlled areas) - - when one has central cooling, and an open central staircase, there is very little personal control. Basically, everyone gets A/C at night and no one during the day.

Our lifestyle/expectations are in conflict with 'the best design' . . .

Jun 6, 2018 2:10 PM ET

Edited Jun 6, 2018 3:56 PM ET.

by Gregg Zuman

Thank you for the rigorous overview of window system options, Martin!

I'm going with Austrian make RIEDER, imported via CEMBRA located here in the Hudson Valley. Of note, I have a "fossil fuel free materials" mission as a bottom line for the project, and these windows come as close as any I've seen on the market - and seem priced competitively with other higher-end makes.

As an agent myself for a European manufacturer, I appreciate that CEMBRA - which is basically Thomas the agent - is a minimal go-between for a high-end European manufacturer as opposed to a service-oriented third party leveraging no-name Eastern European manufacturers (e.g., Yaro). At first, I was turned on by the notion of working with the people at Yaro and even Zola due to their customer service; however, I'm rather hands-on overall on my project (and I've got a groovy contractor collaborating), and Thomas has been great once we connected on the phone (another consideration) as opposed to email.

I learned that the FINISH on windows is everything - sort of the secret sauce (read: skip paint if it pleases you). The Douglas fir tilt and turn wood windows (with aluminum sills) are infused only with a natural oil:

3 layer wood construction. 3-step wood treatment to protect against fungus,
water-damage and to insure uniform finish, all products used are water-
soluble and environmentally friendly.

Check out this U-value:

Glass Type: TRIPLE GLAZING, Ug 0.10, SHGC-Value 51%

I'll wind down for now. Suffice it to write that I'm eager to receive and install them (11 week turnaround after down payment from Austria).

Jun 6, 2018 2:30 PM ET

Edited Jun 6, 2018 3:09 PM ET.

Response to Gregg Zuman
by Martin Holladay

Thanks for the information. (Note to GBA readers: You may remember Gregg Zuman. He's the homeowner whose project was profiled in a GBA article titled "Lead Paint and Old Clapboards.")

GBA has listed Rieder windows in our Product Guide for a long time. Here is the link:
Rieder KG Wood and Vinyl Passivhaus Windows.

Rieder windows are manufactured in Ried im Zillertal, Austria. Here is a link to the website: Rieder GmbH.

Note that North Americans are likely to misinterpret the U-factor you quoted. That's a center of glass U-factor, and it's not comparable to the whole-window U-factors shown on NFRC stickers in the U.S. The whole-window U-factors for Rieder windows are in the range of 0.14 to 0.23.

Jun 6, 2018 4:01 PM ET

Opening windows?
by stephen sheehy

Darlene: I'd be interested in your rationale for having nearly every window openable.

Jun 7, 2018 8:15 AM ET

hi martin, yes my misspelling
by John Williams

hi martin, yes my misspelling didn't help my case thank you and thank you for the add'l links!

Jun 7, 2018 10:12 PM ET

Edited Jun 7, 2018 10:13 PM ET.

Menck Windows
by Kohta Ueno

Menck Windows are manufactured in Hamburg, Germany. A few years ago, the company announced plans to build a factory in Newport, Vermont, and hired U.S. representatives to solicit business at trade shows in New England. A few months later, Menck announced that it was cancelling its plans to build a Vermont factory. The abrupt change of plans left a bitter taste in the mouths of some U.S. customers.

The full story is even more disappointing than this. The Vermont factory was cancelled due to running afoul of investment agreements (https://www.woodworkingnetwork.com/wood-market-trends/woodworking-indust...):

German-based Menck, which builds extra thick style thermal pane windows used throughout Europe, originally wanted to build a 75-employee window factory in Vermont, taking advantage of an EB-5 Immigrant Investor program that rewards foreign investors for generating jobs by investing in U.S. manufacturing facilities.

But a conflict arose over the somewhat complex job creation formula. Use of imported woodworking equipment meant insufficient U.S. jobs were created in the establishment of the window factory to qualify under the EB-5 program.

They then opened up a factory in Chicopee, MA... NESEA had a great tour of the place in the summer of 2015 (pics below). Awesome CNC machines and automated wood cutting. And they closed down in 2017 (https://www.masslive.com/business-news/index.ssf/2017/01/menck.html).

CHICOPEE -- Menck USA, which opened a state-of-the-art window factory in Chicopee in May 2015 with the aid of state economic development incentives, has closed and is up for sale.

The factory at 77 Champion Drive employed about 30 workers. Menck shut down the factory on Wednesday after investors decided not to put more money into the enterprise, according to a letter to creditors released to The Republican and MassLive Friday by attorney Michael B. Katz of the Springfield firm Bacon Wilson.

IMG_5660.JPG IMG_5683.JPG

Jun 8, 2018 5:27 AM ET

Edited Jun 8, 2018 9:48 AM ET.

Response to Kohta Ueno
by Martin Holladay

Thanks for providing more details on the Menck disaster. I'm fully aware of the Vermont side of the story, since the so-called EB-5 fraud case (named for a visa program to lure foreign investment to the U.S.), involving a shady operator named Ariel Quiros, has been headline news in Vermont for years. Quiros is a con man who embezzled funds intended for economic development and used some of the money to buy himself a luxury condo in the Trump Tower building in New York City. Quiros is a villain who is familiar to everyone in my corner of Vermont, since he (and to a lesser extent, his partner Bill Stenger) managed to create economic devastation in downtown Newport and to push our two local ski areas, Burke Mountain and Jay Peak, close to bankruptcy.

By all accounts, Quiros has an enormous ego. Even while he was fleecing Chinese investors for millions of dollars, while simultaneously funneling the money out the back door to fatten his personal bank account and fund his lavish lifestyle, Quiros found time to issue bizarre orders to his employees: the Burke Mountain ski area was re-named "Q Burke" (in honor of Quiros), and every bed in the new Burke hotel was equipped with a wooden headboard bearing a carved "Q" for guests to admire. After the Qurios scandal broke, the new hotel managers decided that replacing the headboards would be too expensive, so the carved Qs are still there.

Like you, I knew that Menck had opened a factory in Massachusetts, but the details you provided help flesh out the story. I've edited my article to include information on the Massachusetts factory.

I had several conversations with Menck representatives in New England, because I was eager to see a local factory making high-performance windows. I spoke on the phone with Todd Bachelder, who was hired by Menck to run the Newport factory -- until it was cancelled -- and I met Russell Chapman at a NESEA conference. Russell Chapman was hired as a Menck rep, and was soliciting window business on the trade show floor.

Jun 9, 2018 1:42 PM ET

Edited Jun 9, 2018 1:53 PM ET.

Too many operable windows
by Darlene Rancourt

Response to Stephen Sheehy ~ your point is well taken (perhaps you noticed from the elevation?), there are too many operable windows. Not only did I miss the opportunity to get a better U factor, if I had more fixed units, but I agree it is doubtful we would open all these operables, anyway.

My lesson, to share with others, is that toiling-away in isolation, I hid 'the forest' from myself while I was so focused and careful with 'each tree'. Every excuse for 'too many operable windows', in the end, sounds too trivial to cause such an oversight - but here I am, it does happen:

I was not interested in a curtainwall face, so my 'teenager-like' architects were pouting and offered no alternatives. At All.

Large windows were in my original, I'm-all-alone-poor-me, plan
-- "Good" News:
-- We had energy modeling results that supported the sizing
-- Course, better if more fixed!
-- There is a lakeview from that face
-- There is intentional winter sun/heat - gathering
-- The prevailing wind arrives into that face
-- There are many fewer windows on the other exposures
-- Some second story large casements will be appreciated as operable (but not all)

Fiberglass frames rarely exceed 72" in height,
-- so I had to use more mullioning to achieve old sizing
-- duh, I didn't take advantage of the re-org to add 'fixed' portions!
-- We actually found ourselves 'excited' about operating the easier-smaller, more weather-resistant, added awnings (and never thought to make the large casements fixed)!

In a side note, recall that all-fiberglass frames (with the benefit of tiny thermal conductivity, like glass) use 'segmented' (straight) pieces to simulate a round shape. This can be a disconcerting feature of fiberglass frames. I have no problem with it, in my situation - attached is a photo of the installed Accurate Dorwin Inc. Tri-pane windows and 'Linear Style' (small frame) Doors, including the many segmented, simulated, arches.


Jun 9, 2018 11:05 PM ET

never in a,million years...
by Ethan T ; Climate Zone 5A ; ~6000HDD

... would I have drawn a facade with so many quarter rounds, but I have to admit that it kind of works.

Jun 10, 2018 11:24 AM ET

Edited Jun 10, 2018 12:15 PM ET.

by Malcolm Taylor

Aesthetics aside, sloped or curved window heads are difficult to flash correctly, especially with a rain-screen cavity. You can't use an end-dam to move the water to the exterior.

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