Are you married to a particular material?

toddinmn, good point about European companies having long lead times and going out of business. They also seem to be more expensive (at least 20% more). And that's not to mention import tariffs.

Besides Marvin and Kolbe, do you have any opinion of Alpen? They seem to offer good performance.

Windows on Washington Ltd: no, not to any particular material, but some of the doors and glass panels are rather large (e.g., 8 feet tall), so sometimes I'm told I can't go with vinyl / uPVC.

Not sure the uPVC statement is correct. Some of the highest DP rated windows are made of uPVC. That said, the Alpen seems to be well regarded.

On the materials front, with specialty operators like a European Tilt and Turn, most folks tend to have some similarly firm ideas about how they want the interior of the home/window to look.

if you happen to be on the west coast (more or less), you might find these guys interesting:

https://www.innotech-windows.com/windows-doors/windows

https://www.innotech-windows.com/innotech-difference/key-performance-data

Also, as you are looking at both north american and european windows, avoid comparing the european u value with the north american u value, they are calculated differently and can't be directly compared.

Because of how they are calculated the european values will look better even if they aren't ... not an apples to apples comparison.

oberon476, thanks! I didn't know about innotech.

(I did run into the European/Metric U value vs. American/Imperial U value issue. It was puzzling before I found the conversion formula.)

David,

Although there is a simple formula for converting European metric U value to North American imperial U value, the result still isn't directly comparable to the U value assigned to North American windows using NFRC guidelines.

Window parameters are measured differently in Europe versus North America. While the conversion will change the European result to imperial, the converted number will look better (lower) than the same european window if it had been tested to NFRC (north american) standard.

For example, a euro-tested window that converts to U .15 (as tested in europe) might actually end up as a U .20 (give or take) when tested using NFRC guidelines. I once saw a euro window at U .15 (converted) that ended up as U .22 when tested to NFRC guidelines.

Again, even with the conversion it still isn't an apples to apples comparison, so keep that in mind when looking at the "higher quality" european windows.

Intuitive and Wasco make tilt n turns also. I am not familiar with either .

oberon476, thanks for the detailed explanation! I didn't know that the testing methods are different. Very good to know!

toddinmn, thanks! I'll take a look at Intuitive and Wasco.

I am in the same position, just getting ready to build. Have you decided on a manufacturer? Are you going for all vinyl, aluminum clad vinyl, or wood clad? We are looking to stay out of the higher range on price and being near SF, CA we are going net zero but don't have to hit higher R values like other areas of the country. Thanks in advance for sharing.

Jessica, I'm most probably going with Alpen, for some mix of tempered laminated SolarControl-6 and tempered laminated SolarControl-9 (TR-6 and TR-9 series). Definitely not wood clad; probably all vinyl. Previously I've been told there's a size limit to vinyl frames from some other suppliers, so you might want to check if you have really large frames. And being near SF, CA, I think you'd want some anti-corrosion coating as well. Let me know what you decide.

Hey Jessica, I'm also in the Bay Area and in the same boat as you. Did you end up going with Alpen like David? Or did you decide on a different brand?

I have had a delay and will not be selecting a manufacturer until the spring most likely. I am not on the ocean side of the bay so I don't think anti-corrosion coating is needed. Would love to hear from others too. This is such a huge decision.

If you are within a mile of the coast I would very much consider using the corrosion resistant hardware were it me.

We bought very expensive Kolbe windows and doors and have been VERY UNHAPPY with their service and follow up and window function. Several of the windows do not open and close properly and the expensive wood front door we purchase has warped. We have been now told that they don't guarantee against warping on their doors. We spent a great deal of money on what we were promised were the best of the best and I would not recommend using them based on our experience

Check out Seemray, for very good uPVC windows, they also have windows certified for Passive house.

Seemray has a beautiful website and looks like a decent window, but why is it that on their website they advertise U values down to .13 in vinyl and .17 in aluminum, yet they don't appear to be in the NFRC data base where their performance claims would be verified?

Good Question, All I can think of is, that,

They are made in Germany and they do make one line (Global70) of uPVC here in Ohio. But i believe they use the Rehau Product line to make their windows and the certification is in EU. They do not say they are NFRC certified. The PH certified windows (Gloabl86) come from Germany and may be that is why. Not 100% sure.

Without reading thru their entire site which I do not have time to do at the moment do they offer verification and testing of this data by any independent agencies?

Amit, that is likely a very good observation

mwm, nothing I saw, but that doesn't mean that I didn't simply miss it

However, the problem as I see it, is that European window companies continually advertise misleading U value information on their websites as well as in their brochures and such which contributes to a false belief that Euro windows have much better performance numbers than North American windows.

NFRC and Euro testing for U value is not the same. NFRC low end for testing is 0° F while Euro testing is down to ~20° F. The warmer low-end measurement used to test to the Euro standard tends to favor wider airspaces.

Conversely while NFRC measures center-of-glass, edge-of-glass, and sash/frame together to determine U value, Euro system measures center and edge of glass the same as NFRC but they separate sash and frame into two separate measurements for U value determination.

And the obvious that Euro U values are metric while NFRC are imperial.

What all that says is that U value performance using NFRC system and U value performance using Euro system cannot be directly compared because they are computed using different measurement systems. But what does it mean for Euro window websites that do list imperial U values?

Two possibilities. First (and best), the Euro window U value performance listed was tested to NFRC standard thus allowing a direct comparison with comparable North American windows. Second, and unfortunately much more common, the original European metric measurement was converted to imperial simply by dividing the metric number by 5.678.

The imperial U value derived from this method is technically valid strictly as an imperial conversion of the original metric performance number, but as explained earlier, it is NOT a valid comparison with NFRC derived U value performance value.

Using this conversion gives a false impression that Euro windows significantly outperform North American windows in U value in a direct comparison between NFRC and the converted European value.

Unfortunately, this conversion is what some European window manufacturers (and their North American representatives and fans) use to compare U value performance to North American windows. Using this comparison the European derived performance value is going to look much better than the NFRC derived performance value. Its apples to oranges.

Exactly oberon and that was where I was going with that. We use commercial glass from Europe/Asia occasionally and the way they figure that and other info can differ greatly.

I’m in the Bay Area, and FWIW my contractor very strongly recommended Marvin; my project is not complete yet, so I can’t report on reliability, etc.but they certainly look great!

Hi Oberon

Excellent details, thank you very much for all details. Your write up was excellent and very clear.

So, after reading your comments, I pulled out the Window Sticker of the Pella 350 Vinyl Windows that I had used to replace the 22 window in my house in Michigan. I replaced my windows 3 years ago. Fortunately, I had saved the Sticker of every window for the city inspector. These Pella 350 are triple glazed and guess what, they are NFRC certified and U 0.18. So, Based on your write up, I would be wasting my money on these European Windows. For example the Seemray is U 0.13 at best, but without NFRC certification. In that case, at best, the U 0.13 is probably U 0.16 or U 0.17. Does that sound right to you?

If that is true, why am I spending 5 time more $$ with these European windows or so called better window. They do look very nice, though.

The only thing we do not have in Pella's and Marvin, is the 5 point locking or Tilt and Turn option.

That may affect the ACH test, worst case. Has anyone tried the ACH test with the American style Casement windows?

One other thing I have noticed with the Pella 350, that the spacers between the glazing is metal, looks like aluminum. While the European windows like Neuffer advertise Swiss made non conducting spacers and their U value is around 0.17 for their Idealu78Plus line of windows. I do not know if Neuffer are NFRC certified. I will check.

I feel like the spacers are not making that much difference. in U value.

Am I missing something here?

If not, I am back to square one in selecting windows for my passive house. :-)

Thx

Amit

I think you might be better served by an American company that sells high quality vinyl windows. Pella is not it, any company can get low u values with the right spacer, foam enhanced frames and the right glass pack. Spacers can be very good made of metal or not, with a slight advantage going to the synthetic spacers. Look at products such as Okna, Soft-Lite , Polaris instead of Pella. The European vinyl windows really only have one advantage IMO, and that is they offer tilt and turn windows.

As Todd pointed out, anyone with the right glass package and a vinyl frame (more than other materials), can build a window that will have good U value (U factor for the purists) performance numbers. Doesn't mean that it's a good window, and doesn't mean it's going to last more than 10 years, but the initial performance can look pretty darn good. It's not difficult.

Examples, Okna a premium, high-end vinyl window company, has a fixed window in their HIMARK line with a U.12 (OKW-K-45), using NFRC criteria. At the same time Plygem, not generally known as a premium, high-end vinyl window company, has a couple of different fixed windows (PWG-M-41) (PWG-M-24) with NFRC documented U.12 performance.

They are not comparable windows, but they have very comparable U value performance numbers.

Although I am an active critic (here and elsewhere) of how Euro window performance is presented in this and other websites that discuss Euro versus North American products, that doesn't mean that I am knocking European windows. In fact I think that the better European companies build some exemplary window systems, particularly some of the wood windows are amazing. And while that doesn't mean that there aren't comparable products on this side of the pond, you may have to look for them. And frankly, some of the best North American windows are based on European technology, exempting the glass package where North American companies can easily hold their own in comparison with Euro glass, coatings, and spacer technologies.

Speaking of spacers, the two European spacers (other than aluminum) that I am somewhat familiar with are Technoform and TPS. TPS is a high end product that is top-end in almost all applications, except TPS does not like high temperature environments, so that can be a consideration. Technoform is middle of the road in performance, despite hype from pro-Euro window fans about superior technology.

In North America the argument is generally metal or non-metal. Metal can be stainless steel, plated steel, or aluminum. Non-metal is usually SuperSpacer and/or Duralite. There are others but these are the two most common.

U value-wise, as Todd mentioned, the non-metal have a slight advantage over stainless steel, and more to much more of a U value performance advantage over the other metal spacer options.

Duralite has the warmest edge, about 1.5°F better than the best of the Superspacer product line (Superspacer had five variants the last time I looked). The best performing Superspacer is about .8°F better than the best stainless spacer, Cardinal's Endur. The Endur is warmer than two of the non-metal Superspacer variants. Longevity and structural I would suggest the stainless is superior, especially when compared with Duralite.

As an additional consideration, folks in North America do have certain ideas pertaining to windows, as do folks in Europe, and not all those ideas are compatible. Window makers in Europe make windows to satisfy their perceived market and window makers in North America make windows to satisfy their perceived market. And those different ideas can and do drive design and performance.

Thanks for your detailed response, oberon476! I'd like to ask for your opinion specifically on Alpen. From my amateur research, I've found them to be a decent choice among various brands that offer tilt-and-turn, but I want a more professional opinion. Thanks in advance.

Alpen makes a nice window with the best U factor ratings available anywhere.

The secret to their success is the Heat Mirror glass system. Heat Mirror substitutes layers of Low-E coated plastic film rather than glass between outer glass lites in multilayer IG units to achieve very impressive performance values. Essentially, they can build a triple pane or quad pane IG unit without concern for the additional weight and thickness of conventional all-glass multi-pane IG units. You can buy an R10 or U.10 window from Alpen.

The downside of their glass system is very low VT on some of their best performing products (30% range) and the potential for either increased risk of seal failure or plastic film failure versus more conventional all glass IG systems.

Several other companies have used Heat Mirror in the past and eventually dropped it because of massive failures. Alpen has claimed in the past that they have had no failures due to using Heat Mirror system, but I don't know if they still make that claim or not.

We worked with all of the window manufacturers mentioned in any of the comments above because we helped their customers finding window shades for their tilt and turn windows. We meet our clients right after they got their new windows or moved in and there is very little complain about any of the window makers. Though there are some recommendations I can give:

use a window that has a local dealer or builder - you WILL need somebody to adjust your windows after a year to make sure they function properly. Use the energy performance you need - a passive house windows doesn't do you any good in a hot climate. Chose the material that suits you best - uPVC, wood, aluminum or aluminum clad. Get your out the door price from the manufacturer you are interested in to be able to compare local, domestic or international suppliers.

Best of Luck on your project...

Thanks, oberon476. I had also read about that issue with Alpen, but I thought that was a few decades ago and they had already fixed it.

Just to be clear, Alpen has stated that they have never had the problem with suspended film failure that plagued pretty much everyone else who used it.

Although I have seen a number of houses that had failed heat mirror film, the last one maybe 5 years ago, none of the ones that I have seen had Alpen windows installed.

Thanks, oberon476.

I raised this issue with one of their representatives last year, and here was his response:

-----

We have been manufacturing Heat Mirror insulated glass units since 1983, and it continues to be our core product offering. Over 90% of our windows and doors incorporate HM glazing. Heat Mirror was unfairly given a bad reputation when Hurd Windows began using it in their wood windows, which were never designed for use with HM IGUs. They used single seal IGs in a skinny wood sash which were prone to allowing water to seep into the glazing pocket. For two decades now, we have been using a dual seal process (a polyisobutylene bead between the spacers and polyurethane around the perimeter). We have a very low incidence of seal failures. About ten years ago, we built a factory on the 4th floor of the Empire State Building to build Heat Mirror IGUs and re-glazed over 6500 windows in the building. We have yet to see a single failure.

If for some reason a seal failure did occur with one of your windows, it is covered in our warranty: https://thinkalpen.com/wp-content/uploads/2018/06/Alpen-HPP-Tyrol-Residential-Warranty-2018-02-v3.pdf

-----

Thank you Oberon 476, David and Fenstermann.

After reading all the information from all of you, I will get a quote from Alpen, along with the other window manufacturers based in USA.

This was a very educating exchange of data and information.

Sincerely

amit

Anybody use innotech windows?

By the way, I'm going with Zola in the end, as they provide both tilt-and-turn windows and big 9' tall lift-and-slide doors. But I want to also highly recommend Alpen as they have always been responsive, patient, and helpful to me.

I have Innotech in my home

I would highly recomend Innotech Windows and Doors. They offer the best of both worlds - European quality with North American support and manufacturing.

So would I, but they are regional to the PNW (Vancouver) and not generally available elsewhere unless something has changed over the years?

I am in the midwest and have them, but that was due to some very specific circumstances at the time.

I purchased two 8' wide sliding glass doors from Alpen in April of 2021. They were delivered and installed June 2021. One fixed panel had a scratch inside the glass all the way from top to bottom. The handles were wrong and the new handles and new fixed panel didn't come in until August 2021. The doors are painted with a thin coat of marine paint that scratches off very easily. The old handles and the new handles swim around on the door and scratched all the paint around them. I spent all day touching up all the paint scratches and dings on both inside and outside the doors. Their idea of preventing the handles from swimming around is using loctite on the screws which didn't work. They did not like my idea of some sort of sleeve around the screws to prevent the handles from moving all around. I'm worried about how the paint will hold up since it's so thin and easy to scratch. Just my two cents. I guess we will see how they keep out the cold this winter.

Hi @harknesshome - Thanks for your feedback. We are building a new home with lots of windows and are strongly considering Alpen & Marvin. Alpen windows are 30% more than Marvin essentials. Apart from the ones you mentioned, how would you rate the Alpen windows? Thanks!

Hello karthin77 - I can't comment on their windows. We only purchased sliding glass doors for our remodel project.

I have commented before on Kolbe windows. We have a large house completed 2 years ago with all Kolbe windows and sliders. I love the look and the windows that work are great-- but we had several problems and many of the windows do not close nicely which is very disappointing for such an expensive window. We have had a TERRIBLE time with service....wait many months in between being able to contact anyone at the company and follow up takes another few months. We are STILL pending some repairs to several faulty windows they they inspected.

Operational issues are most often, most often, the result of poor handling and installation. They have them pretty well figured out at this point to be perfectly honest. If it was part of a new build, many times the framers will set the windows and they can be a bit on the "rougher" side when it comes to material handling.