On 11 Jun 2005 23:32:08 GMT, Ian Stirling
wrote:

I've also wondered why CO2 is not used, as it would seem to have about the
same performance as argon fill, but at a fraction of the price.

Argon has a low thermal capacity, even at low pressures, that helps
with the loss due to convection from one surface to the other, the
saving is probably low, but with larger windows used these days than
before, every little helps. Plus, it makes them sound high tech.
--
I think computer viruses should count as life. I think it
says something about human nature that the only form of
life we have created so far is purely destructive. We've
created life in our own image. - Stephen Hawking