QUOTE(charlesandnessa @ Sep 22 2007, 06:03 PM)

sounds weird to me but every time i've found my windows fogging up, it means i need to clean the inside of them. i have seen something in euope that works to prevent fog too, some cloth treated with some chemical. maybe some of our vj germans can tell us more.

In Canada we have double paned argon filled windows (generally), so what happens sometimes is that moisture gets trapped between the panes (usually, they say, from just the heat/cold/heat/cold) - looks bad!
Anyway, after they drill the holes they wash out the area between the panes and then do the venting - what an improvement! Apparently the windows still have a fairly good "R" rating even with the venting.