Greenbuilding Archive for January 2001

["mac12" <tomthomas@uswest.net>]

Some notes on insulating glass:

Argon (and any other gas) will try to exit a sealed unit and will be
successful to some extent (depending on the material and workmanship of
the seal).
Any ambient gas will try to enter a sealed unit and will be successful
to some extent (depending on the material and workmanship of the seal).
This has absolutely nothing to do with "partially collapsed" units.
The causes of these units are most likely:
         The unit was manufactured at a higher elevation than where it
was installed and the atmospheric pressure imbalance is forcing the
panes together.
         The unit was sealed while in a horizontal configuration and the
weight of the upper pane caused it to sag.  Once the unit was sealed,
the reduced volume inside the unit was retained and the panes stayed
bowed inward.
Perhaps by imploding you mean a broken pane with no visible sign of
impact.  I have seen instances in which a unit with the sealant too
rigid for the strength of the glass caused breakage parallel to the
spacer.  This happened most frequently with a metal frame and was
related to temperature changes the unit encountered.

I used to make the beasts in a prior life.

Tom Thomas
Macurco, Inc.
"Gas Detection"

Stephen Thwaites wrote:

>
>  cneurath wrote:
>
>>  As to the issue of whether the argon or krypton leaks out of the
>>  window after a number of years ... my guess is that if the argon or
>>  krypton leaked out it would be replaced with ambient air. Then the
>>  window would fog up the same as when a sealed, air-filled window
>>  leaks.  It is the water vapor getting inside that is the tip-off to a
>>  broken seal.  If there is no fogging, then presumably you've still
>>  got all the argon you started with.  None of my argon filled triple
>>  pane windows have fogged up yet, but the oldest are only about 7
>>  years old so that's not saying much.
>
>
>  I'm told that i should remember the Law of Partial Pressures from my
>  higher schooling; i don't but that's another matter - the law says that
>  argon only sees the world of argon.  So argon will always want to
>  diffuse out of a sealed unit, even if nothing replaces it.  There is
>  some speculation, repeat speculation, that this is the cause of some
>  imploding windows.  Based on an article in a window trade magazine a
>  year or so ago, there seems to have been an increase in this rare event,
>  mostly in units sealed w/ silicone.
>
>  Besides water vapour between the glass an imploded window would also be
>  sign that argon was leaking out, although by then the whole issue is a
>  bit academic as a broken window holds no argon.........
>
>
>>  Oh, and now that I've looked up Kate Offringa's web link I see that
>>  site answers most of these questions too.  But I didn't see any
>>  window maker sponsors from Canada which has the most energy efficient
>>  windows in North America as far as I can tell.  It's too bad there is
>>  such an information barrier between the Canadian and U.S. window
>>  markets.
>
>
>  I have to admit that sometimes we are not good joiners.  I haven't
>  looked at the Energy
>  Star or Efficient Windows Collaborative Sites recently, but will when i
>  get back to my office next week.
>
>  Our inital relectance to join these groups stemmed from the fact that
>  most
>  industry groups are advocates for status quo energy
>  performance. We'd like to think that we are better that.
>
>  Most US window makers are focussed on air conditioning loads, as that is
>  the main concern in the majority of their market, so they don't offer
>  windows optimized for passive solar applications.  Industry pressure
>  seems to have stalled a more realistic rating system for passive solar
>  applications like the Canada's Energy Rating system. This approach
>  reconciles all of the losses (glass, frame, air leakage) with the
>  passive solar gains.  A positive rating means a window gains more than
>  it loses. US rating systems focus only on the losses.
>
>  Now if there was a Super Window Council....
>
>  Stephen Thwaites
>  Thermotech Windows
>  Ottawa Ontario
>
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