"FDR" writes:
When the seal breaks, the argon gas that is normally sandwiched in between
the panes will escape rendering the insulation value to nearly
nothing.

Which, it bears mention, is only slightly worse than the insulation
value of argon gas! Gas is not a terribly good insulator.

The biggest problem with seal breakage is the appearance of the
moisture, and as another poster said, any appearance of moisture is
too much.

Best Regards,
--
Todd H.
http://www.toddh.net/