On a double hung window (the kind you can tilt out and clean), our lower sash (glass is approx. 27x28) is smashed. I don't want to replace it, since it's between the living room and enclosed porch. We would like to just lower the upper sash, have that as our simple see-through (spy-on-you) window which doesn't open, and somehow fill in the upper part...with something, even a wall if necessary. Any ideas how to best do this?
I don't agree with the plan from a resale standpoint. But yeah, you could simply remove the window trim and screw drywall over the top sash to then cut the side trim down and glue the trim's top piece to the drywall to just frame the bottom sash.
I envision the window to be vinyl, so you could screw drywall or painted plywood right to the upper sash and even hang a picture or clock on it, to kind of give it a purpose.
Personally though, I'd remove the window and reuse what I could to make an actual pass-through or plant-shelf. This would be a few inches wider to the full width of the jamb, since the window would be gone. Then, you could have a custom height with even an arched or pointed top design.