Will my new line of fire hydrant shaped lawn ornaments catch on with the general public?
Has it occurred to you to call ask?
The reason to fill the space between double-pane windows is to keep out moisture, which would soon seep in if the space initially had a vacuum (which would be a good insulator). Air contains oxygen, which would tend to deteriorate the window frame and seal materials. Thus an inert gas is required. Krypton would qualify, but would be prohibitively expensive, so it is unlikely to be used. Nitrogen is the most likely gas to be used. So your guy is probably blowing smoke.
