For years I had old leaky metal windows in my house,,,
Every fall I would put up plastic on the inside on my windows.
Then at night I would put up 1" "pink board" (pretty cheap)
We cut it to fit, then glued fabric to both sides,,,
It made an amazing difference,,,
And it didn't cost a lot.
Is is kind of a hassle to put it up and down all of the time,,,
Plus you need to store them someplace.
Les