"Tom" wrote in message
...
Be sure to do some cost calculations first. I considered replacing the
single glass windows with double paned insulated glass in my Minnesota
house a few years ago. I was going to use the existing sash and replace
only the glass. I gave up on the idea when I calculated the payback to be
something like 15 years (if I remember right). Going from one pane to two
only increases the R value from about 1 to about 2 which is still very
low. Such a small change in thermal transfer for such a small area does
very little to improve heat loss and insulated glass is expensive.

Going to insulated glass may offer the benefit of more comfort if you're
sitting near the window, but don't count on it to save you any money.

Spending money on air infiltration by weather stripping is much more cost
effective.

I agree but, I'm only spending $2000 to replace 10 large windows averaging
20sqft each, with low-e argon which increases the R-value from 2 to 4 for
only 20% more. I expect to receive approx $1500 in rebates which makes my
net cost about $500. My main concern is comfort and resale value not payback
but I just could not resist such an excellent deal. Of course my labour is
'free'

Reducing air infiltration, increasing attic and basement insulation are all
part of the project.