Basement window insulation

[JDgreen227]

I just finished installing the inside window insulation I put on every fall. Have seven Anderson single pane tilt-in basement windows with an external storm pane, and inside I first add 1" of R-5 foam, then a layer of fiberglass R-13, then 2-3 more 1" R-5 layers of foam. Since the entire basement is insulated with stud walls and R-13, I think it makes sense to cover the windows too. I sometimes wonder how much heat loss through the glass my window insulation prevents....anybody know of a source for that information? Thanks.

 

[Tig]

Try this

Run it once with your windows detailed, once without. Compare the difference.

 

[JDgreen227]

Try this

Run it once with your windows detailed, once without. Compare the difference.

Thank you for the link...I ran it one time with the windows listed as single pane, then ran it the second time with the windows omitted as they are better insulated than the walls when covered...the difference in heat loss between the two was about 4.5%