can I put insul foam in a window jamb?

I have a window that faces south and I get a lot of solar gain from it. It has double glazed insulated glass in it. If I put foil faced insulation board in it I would have about 4″ between the glass and the foam. I could just cut it tight and friction fit it in the jamb.
Will this make the window to hot? Will it damage the window? Should I allow for some ventilation by having some small holes at the bottom and at the top? Or just seal it up?
This is a bedroom and in the evening it is warm because of the solar gain. I’ve installed a ceiling fan but am also trying to lower the heat gain.
Replies
Can you open the window a bit?
Stick a thermometer in there and see what's happening, open the window enough to keep the temp down?
Joe H
I thought of cracking the window open a bit. I don't like the idea though. It seems like it could damage the seals by having them exposed for a long time.
Are you putting the foam outside or inside?
I'd bet inside would melt the window.
Bob's next test date: 12/10/07
I was thinking of inside but you might have a point about the outside. I don't like to have weird stuff on the outside because it looks bad but maybe I could face the foam with something. Someone here suggested an awning which is what needs to happen. So putting something on the outside is temporary. Is one year temporary?
I think if I put it on the inside the temps are going to be very high.
That's it. I'm putting it on the outside!
We have had reflective films applied to the inside of many of our south facing windows in the office building where I work. It helps a ton, causes no harm and doesn't look bad from outside.
I'll try to get the product name if you like.
Thanks! I'd try that.