? if natural gas can for in pockets underground ( gas fields ) then why cant argon?

Posted By: jamesingramIf, as Tony suggested the argon is not replaced with air ( carrying water molecules) then what would it be replaced with as it leaked out ?

It will be replaced by some mixture of the various gasses that make up air - in proportion to their relative diffusibility (if that's a proper term). Water vapour might or might not diffuse in faster or slower than the rest - anyone know the relative figures? In any case, air isn't an integral substance - it's a mixture of substances that can each behave independently in some situations, like this.

Posted By: # Mark SiddallGas leakage from double glazed, double sealed, units varries with sealant type. Using old 1990ish technology: -

Polysulfide 5% to 6%
Polyurethane 2% to 5%
Silicone 12% to 15%

I should think there's huge, and common, variability within those figures - many units would lose almost nothing, others would lose most or all quite rapidly.

Posted By: skywalkerIt appears that there is an acceptance of loss of Argon at a rate of up to 1% per year in the best sealed units (under test conditions). Another stat' is that 50% and above Argon concentration has a measurable affect on U value (unfortunalely we can't see the table referred to). Each 10% Argon is apparently 'worth' 0.01-0.02 W/m2K with Argon fill described as decreasing U value by between 0.1 - 0.2 W/m2K (not sure I believe it is a straight line - anyone care to comment).

I also doubt it's a straight line. My hunch is on the favourable side - performance deteriorates slowly as concentration drops from say 90% to 80%, but deteriorates much faster from say 50% to 40%, and probably becomes a negligible advantage at say 30%. What's others' guesses?

Posted By: jamesingramI was charged £6 m2 for argon filling , not that much really in the skeem of things.

I agree - do it (argon) as it's dirt cheap, but don't rely on it. Rely instead on triple glazing - again with argon if you like.

From http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=527&page=3

Johan said >the 3G unit was cheaper the a 2G unit!<

fostertom said > Just saw this on http://www.buildinggreen.com/elists/furnacefree.cfm:
"Be sure to use krypton, which insulates twice as well as air, not argon, which is only 1/3 better than air and has a wider optimal gap. Extra cost is zero to negligible, because you use not 99.999% lab-grade krypton but only first-distillate-stage Kr (around 60-70% Kr, rest Ar, indistinguishable thermal performance -- same Kr as goes in those lousy "watt-saver" fluorescent tubes". This is USA - Krypton's much more expensive here? What is the optimal gap for Krypton? and for Argon? - is that different from the 16mm for air?<

Another advantage of krypton (if only you could rely on it) is its optimal gap of 6mm, versus air and argon 16mm (12mm tolerable). Thus 4-6-4-6-4 krypton-filled will fit in any old 2g-intended rebate but will be completely useless as soon as the krypton leaks out - whereas argon requires 4-16-4-16-4 (Passivhaus window standard), or at least 4-12-4-12-4 (Scandinavian-style 3g standard) and will still perform better than any 2g unit once the argon leaks out.

Tom,

With regard to glass spacing, and our old standard of 4-12-4-12-4 with argon, this has now been amended to 4-10-4-14-4 and Krypton, but only krypton, never argon.

Have you tried Pilkington Spectrum, somewhat biased towards Pilkingtons products, but certainly gives you half an hour of playing with cavities, glasses and fills.

The Krypton, and the same applies to Argon, we are now filling both cavities, rather than just the one. More expensive to fill, but easier on the production line to only have one gas into one unit.

The test results showed 4-10-4-14-4 to be the marginally best performing, this is despite what theoretical figures suggest.

As for existance of gas over the units life. I shall continue to investigate performance tests on our older windows in Sweden.
I obviously have vested interest in telling you the gas will still be in there, but I need data for you to believe.

On a south facing window, you get a bigger difference between internal and external temperatures so condensation is more likely to become visible. The north facing units may also have failed but it just isn't noticeable.

Is this thread still the best of our knowledge (i.e. on a good day 1% per year...)on this or are there any improvements or more data in the last three years?

I'd think that Krypton would be slower to leak away as its about 10% bigger than Argon - Any thoughts?

several people i know in the window , dg unit manifacturering business , think it is a waste of money as it leaks out , but the're happy to charge me more to fill them
i had 4 unit blow last winter in the heavy frost on some upvc windows ( 11 years old ) I presumed they were sitting in mositure and the frame weren't draining due to te low temperatures
I replaced then with lowE argon filled . lets see how long they last