I'm thinking to cut to fit pieces of 2" polystyrene for my shop windows for
use in the winter (east and west) and summer (south). These are double hung
windows with a good 2" recess where the foam should fit in fairly well.

Other than it being 'pink' - it should be about an R10. One sheet should
cover 3 of my 4 windows and hopefully significantly reduce the amount of
hours on my electric heater.

This is for my "office-side" of the insulated shop. 23x11 with a 220V
heater. Four 34 x 44 windows.

I was also thinking to spray adhesive aluminum foil to one or both sides
(sun exposure side in the summer).

The sheet was $24 and should be enough to cover 3 windows.

Thoughts?