I downloaded the Red Book and read it through.  It's informative, but two questions came up:

Page 15, figure RB15-2, "Air space heat transfer":  The graph shows that adding Argon to a double pane window increases the radiant heat loss by about 5%.  Can any of you explain why?

Page 19, figure RB19-3, "Comparison of insulating value and solar gain":  The table has two lines for Double Pane with LoE2, one shows high solar gair, the other low.  Do any of you know what it was intended to show?

(I asked Cardinal, but didn't get an answer.)

Thanks for any information that you can provide.

Very respectfully,
Larry

Is Cardinal a window company, or glass mfr? What's the link to the book? I'd like to look at it. Thanks.

http://www.cardinalcorp.com/data/pdf/RED-BOOK.pdf

Man, couldn't you have asked an easy question? :-)

I looked for an answer but it seems like every promising Google hit goes to a scientific or engineering document you have to pay to see!! I think it probably has to do with what's called attenuation, i.e., how much the gas filters or scatters the electromagnetic wavelengths that make up thermal radiation as they pass through the medium. I'm surmising thermal radiation travels more easily through argon than through nitrogen and oxygen which is what air is mostly made up of.

It looks to me like there is a typo in the figure. The first LoE2 should be LoE. That makes the graph consistent with the discussion above it.

Interesting booklet. Lot's of good technical info. Just the sort of stuff that tickles my engineering nerd genes!!!

Thanks demaceld.

Yes, it is an interesting booklet, and a lot of information for a free download.

LoE to LoE2.  Yes, that does make sense.

On the Argon: I was guessing a selective filtering also, but I'd not found any resource that addressed it. 

Very respectfully,
Larry

I am not sure why Argon would suffer greater heat loss compared to air, but it might be related to density. Argon is a very small molecule compared to oxygen. As to the Redbook, it is not entirely up to date as it talks primarily about products that are not current generation from Cardinal. Unless Cardinal has put out another one.

Cardinal is the largest Glass Fabricator in the U.S if not the world and makes Inuslated glass for most of the major manufacturers (Andersen, Marvin, BiltBest).

You can find a link to the Cardinal energy Use Calculator at this page on BiltBest.