GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Audio Play Icon Headphones Icon Plus Icon Minus Icon Check Icon Print Icon Picture icon Single Arrow Icon Double Arrow Icon Hamburger Icon TV Icon Close Icon Sorted Hamburger/Search Icon
Musings of an Energy Nerd

Windows for High-Altitude Homes

How to specify insulated glazing units that can handle changes in atmospheric pressure

If you specified Alpen Windows for your high-altitude home, the units will probably be delivered with a funny-looking mylar balloon attached to a thin capillary tube. The balloon contains argon, the same gas used to fill the gap between the window panes, and is part of a proprietary system to address problems associated with the low atmospheric pressure at high elevations. [Photo courtesy of Alpen High Performance Products]

Most modern windows are equipped with double or triple glazing in the form of insulated glazing units (IGUs). These IGUs have an airtight seal at the perimeter that traps some type of gas between the window panes—usually argon, but sometimes krypton or ordinary air.

Ideally, the IGU perimeter seal is permanent. If the IGUs are filled with argon or krypton—gases that improve the IGU’s energy performance—you don’t want any of the precious gas to leak out. Moreover, you never want any humid air to enter into the space between the glass panes, since the entry of humid air can lead to condensation between the panes (sometimes called fogging).

IGUs perform well when they are installed at an altitude close to that of the factory where the IGUs were assembled. However, if IGUs from a sea-level factory are transported to a job site at a high elevation—usually defined as a location above 5,000 or 6,000 feet—then all kinds of bad things can happen:

Window experts have been aware of the problems associated with high-altitude installations of IGUs for decades, and many technical articles address the problems. Back in 2000, for example, BuildingGreen published an article on the topic called “High Elevation Problems Jeopardize Gas-Fill Windows.”

The article referred to a class action lawsuit against Hurd Windows, in which the plaintiffs alleged that certain Hurd Windows may not have had the U-factor promised by the manufacturer, since argon may have leaked out of so-called “breather tubes” installed to address issues related to high-altitude installations. In response to the suit, Hurd Windows eventually agreed to a $5.3 million settlement.

The large settlement shook up the window industry. After the Hurd settlement, almost all window manufacturers understood the need to carefully examine available options to address these high-altitude installations.

In order…

GBA Prime

This article is only available to GBA Prime Members

Sign up for a free trial and get instant access to this article as well as GBA’s complete library of premium articles and construction details.

Start Free Trial

5 Comments

  1. Hugh Weisman | | #1

    interesting story....it brings to mind a project we had about 20 years ago on the east coast...we initially wanted to use windows from a manufacturer in the northwest. We were told that transporting them to the east was problematic as they couldn't come over the Rockies as the altitude would affect the insulation value. Eventually, they worked out a route that took them south down to New Mexico where they wouldn't exceed 5,000 feet on the trip to the east. For one reason or another, we ended up with another window as best I can recall.

  2. qofmiwok | | #2

    What about the elevation while the windows are being transported, is that an issue? ie Even if the windows are made at 5300 feet and I am in Idaho at 6200 feet, the windows will pass through lower elevations on the way.

    Also, I am having a heck of a time finding high R value windows (for climate zone 6b; maybe I don't need R8 or 9 as PH would require in my climate zone, but at least R6 or 7). Unfortunately Alpen doesn't make them, nor most I run into. Have other leads for 6000 elevation R6-7 with wood interiors?

    1. User avater GBA Editor
      Martin Holladay | | #3

      Qofmiwok,
      Q. "What about the elevation while the windows are being transported, is that an issue?"

      A. Yes, that's an issue, as Hugh Weisman already mentioned in Comment #1. In general, the Rocky Mountains form a divide for U.S. window manufacturers; if you live east of the Rockies, you'll probably be buying your windows from a distributor or manufacturer located east of the Rockies, and if you live west of the Rockies, you'll choose a distributor or manufacturer from your side of the mountains.

      Here is a link to an Alpen Windows web page that discusses their windows with a U-factor of 0.10 (that's R-10) -- that should be good enough to meet your needs, shouldn't it?

      1. qofmiwok | | #4

        Thanks. Yes R10 is more than enough, but they don't come with wood interiors on tilt-turns.

        Also, my question about elevation is whether it's the initial and final elevations that matter, or the temporary transport through a higher or lower elevation.

        1. User avater GBA Editor
          Martin Holladay | | #5

          Qofmiwok,
          Q. "My question about elevation is whether it's the initial and final elevations that matter, or the temporary transport through a higher or lower elevation?"

          A. Either one can cause problems.

Log in or become a member to post a comment.

Related

  • Blogs

    What Windows Should I Buy?

    Designers and builders talk about their favorite window brands

  • Blogs

    All About Glazing Options

    You’ve chosen a window manufacturer, you’ve selected the frame material, and you’ve decided on casements rather than double-hungs. But how do you specify glazing?

  • Blogs

    All About U-Factor

    It’s not a simple topic, so get ready to untangle a few knotted threads

  • Green Homes

    Energy-Efficient Straw-bale Home in the Colorado Rockies

    By Doug Graybeal Our house is located outside of Carbondale, Colo., at an altitude of 7,000 feet. The architecture is both responsive to the climate — a dry mountain environment…

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |