Will gas in windows diffuse prematurely at a high elevation?
mjezzi
| Posted in General Questions on
There’s a lot of hearsay about krypton and aragon diffusing from windows at high elevations, and I’m wondering if there’s any truth to this.
I’m building a passive house at 7,000’ elevation. And the windows are wood framed, aluminum clad European style and will have either krypton or aragon gas in them.
Does anyone know at what rate of diffusion at this elevation will be? Is it a false belief that gases are not effective in windows at elevation?
The windows will be produced with bladders to allow pressure to adjust when they reach their destination/elevation in Colorado, and will be crimped on site.
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Replies
Mike,
You should probably read this article: "High Elevation Problems Jeopardize Gas-Fill Windows." (Caveat: The article was written in 2000.)
The authors of the article, Peter Yost and Alex Wilson, are skeptical of the "leave the breather tubes open during transport and then crimp them shut on delivery" solution. They wrote:
"[One possible solution is to] Install capillary tubes that need to be crimped closed during installation. This was Hurd’s seemingly reasonable solution. For two reasons, however, no manufacturers currently take this approach: 1) the NFRC policy prevents them from taking any rating value from the gas fill, and 2) the liability risk is just too great—at least for U.S. manufacturers. (Leftover funds from the Hurd settlement—reportedly some $50,000 —are just now being donated to two local Habitat for Humanity affiliates on the West Coast, per terms of the settlement.)"
It's a complicated issue, and you'll have to make your own judgment on how to approach the problem and whether worrying about the problem is fruitful.
Thanks for sharing Martin.
After posting the question and doing more googling, I also found this article from 2016: https://spectrumpagosa.com/windows-in-high-elevation-making-sure-that-your-windows-are-compatible-with-elevations-above-5000-ft/
It sounds like capillary tubes or breather tubes are open systems that are not really intended to be crimped, but bladder or balloon systems are closed systems that are designed to be crimped.
Your 2000 article cites the quote “We investigated a bladder system and found it either unworkable or impractical or both”
Alpen is one manufacturer I know that uses a closed balloon system that gets crimped on site, so there is at least one manufacturer that has found a way to make such a system practical and workable.
So it’s my impression that breather tubes don’t work for the stated reasons in your article, but balloon closed systems do work. But it also doesn’t sound like there’s an easy way to prove that balloon closed systems do indeed work as advertised. I’ll inquire with the manufacturer.
I would add that once any gas diffusion at high altitudes has equalized the pressure inside and outside the IGU assembly, future diffusion rates shouldn’t be any different from the same window at lower altitude. Basically diffusion rates may be a bit higher early in the window’s life, but later on pressures will equalize and the window should age the same as it would at lower altitudes.
I think there are a few other window manufacturers around the Denver area besides just Alpen, so you should have some options where the high altitude won’t be an issue.
Bill
That was the answer I was looking for. Thanks Bill!
Mike,
Not sure who supplies windows around Denver that have the same bladders as Alpen, but perhaps because the windows in Denver would be assembled at 5,000 ft, the trip up another 2,000 wouldn't be stressful for them. I am at 8,000 ft and my Alpen windows presumably made the trip over at least one pass at 10,000 to get here. The bladders did their job just fine and best as one can tell, since argon is invisible, the windows are full the way they should be. The performance of the windows is everything I expected. Crimping and hiding the capillary tubes was a bit annoying, but quite doable.
That said, be sure to have written confirmation of what gas you will have in any window and the warranty of altitude for same. Four years ago when I was ordering windows, I found that Marvin, Sierra and others would not ship windows over anything from 4000 to 6ooo ft with argon in them. Alpen would and they won. And I am plenty happy with them.
Bill is right in regard to diffusion once pressure balance is achieved after installation. If your glazing unit is leaking argon out, then most likely you will be leaking moisture in as well. Internal fogging in double or triple glazing typically means a seal leak and a possible warranty issue. Be sure to read the fine print regarding loss of seals.
You might also want to consider the type of spacers used in whatever window you select. It may be more nerdy than you want to get. The overall performance numbers for the window should be of primary concern. However, some spacers will cause more condensation issues than others.
Whatever I learned about gas fill in IGUs, I got from a guy named Randi Ernst, who is certainly retired now, but who owned a leading gas-fill technology company in the upper midwest. Really smart and cool guy.
As I was writing that article back in 2000, Randi was just starting to work with a new device that could non-invasively measure the remaining gas fill in existing IGUs. Pretty sure it was this company: https://www.sparklike.com/en/. My recollection is that even after 20 years, most IGUs were above 90% of the original gas fill.
So, you can't stop diffusion but most IGUs do fairly well over time, all things considered.
Peter