Natural Air vs. Argon Gas

[NeauxWay]

A window vendor, quoted me natural air-filled sliders and when I asked about Argon or Krypton gas, he told me that the savings in heating was virtually negligible (maybe $15-25/year) for Argon gas filled windows even though the published u-values for these windows are 0.46 and 0.29 for Air and Argon, respectively. Is there any factual basis in his claims or is he just trying to move inventory or something like that?

The house is in Connecticut, about 3000 Sq Ft and doesn't get all that much sun except for one room, which has very large windows (two 8X8 sliders and two 6X8 picture windows). Also, in this room, would it make sense to get a different type of window? For example, a different SHGC value? I usually WANT the window to generate heat, since the winter is long and at times brutally cold and in the summer I turn on the A/C maybe 5 days? Does that make sense?

Thanks.

[Cheryl (Fenessa)]

Argon over air fill alone will not make that dramatic a difference in U-value. I suspect the lower U-value includes Loe2 as well. Typical improvements in dual pane units that have Loe2/argon over Loe2/air are in the range of .03 to .04 (for example U=.32 or U=.29)

[NeauxWay]

Yes, I think it it does include low-e, as well. So it is the low-e that affects the u-value more than the argon gas? I'll have to get clarification about that from the salesperson.

Also, a novice question - how do you know whether the glass that is installed is actually low-e and argon gas filled? Is there a way to verify this, other than blind faith in the integrity of the contractor?

[Oberon]

NeauxWay,

I would also agree that the difference in U value that you were quoted certainly appears to include an argon and LowE upgrade.

There is really no way for you as a homeowner to know if your window contains argon (or any other gas), but to tell if a window has LowE is easy.

Wait until it is dark and then hold a lighter up to the glass. If you see two flames reflected in the glass, then you don't have LowE. If you see three flames reflected in the glass, you will notice that the center flame is a slightly different color than the other two (flanking) flames. That center flame is the reflection of the LowE coating.

Depending on which flanking flame the center flame is closest to will also tell you what glass surface has the LowE coating. In most circumstances, you want the LowE on the number 2 surface, which is the interior side of the exterior lite.

One advantage of LowE is that it replaces "room air" in the window. Depending on the manufacturer, that might or might not be important.
There are even discussions even within the window industry over the value of inert gas infills, so don't feel alone!

Personally, I would get the argon gas, but only if it is a very minimal pricing upgrade. Argon is not expensive to the window manufacturer, and for the most part the window manufacturers don't try to gouge folks for that upgrade.

Concerning the LowE upgrade, by all means get it. Absolutely.

[Oberon]

Sorry, I had a slight (or not so slight) mistype in my previous message.

I said "one advantage of LowE is that it replaces room air...".

Obviously, that should have said "one advantage of argon or any inert gas or mixture...". Well, a bit longer then.

Anyway, sorry for any confusion!