I was asked by a member here what I use for insulating the windows during the winter.
This old house out here in the middle of nowhere on the Nebraska plains is little more than half windows, an anomaly in architecture in the colder regions, but one of the reasons I like it. I never liked living in what seemed to be a hole, or a basement. I like light, openness, and the more, the better.
But of course during the winter, this presents problems when it comes to keeping the interior of one's house warm.
Ever since I've lived here, I've used generic transparent (or semi-transparent) plastic sheeting, and as it's easy to save for the next winter, some of the window coverings I have are on their seventh winter now.
"Window kits" are more expensive, and one can "tailor" them only so much.
The hardware store in town sells plastic sheeting off of rolls, by the foot or the yard, and it's considerably cheaper than what one gets with "window kits."
The plastic sheeting's of various thicknesses; I usually buy the heaviest-duty, thickest, stuff, and it's still cheaper than "window kits." One gets several yards of the stuff, and cuts it to fit each window.
Now, one can't just staple-gun the plastic to the outside window-frame; one needs to keep the plastic from ripping away from the staples. I take really light-weight cardboard and cut it into strips, and use those.
And then in spring, it's an easy matter to just take a pair of pliers, and yank out the staples.
The thickness of the plastic, and whether to use one layer or two, depends upon the weather where one lives; I use two layers, and while it "blurs" looking outside, one can still see outside reasonably well.