The insulation material for windows is called "reflectix" IIRC. I use it
for my popup camper. I put it on the outside of the tent ends when its
popped up. It helps keep the interior cooler. Some folks go so far as to
put it in their zippered windows too when the windows are "curtained".

I didn't bother to edge it. I use spring clamps to clamp it to the roof
at the seams.

Hey, its airplane related...I take my popup to Oshkosh!

John