I'm helping someone who moved into an older rental house with very old windows. The house is great but as shown in the pictures, some of the windows have significant gaps, so of course air (and even some dirt) is flowing through the gaps (heated or cooled = $).
What can I use to fill those gaps year-round but allow the window to open?
I've tried applying the thin white foam insulation but on these uneven windows, that can cause the window to not latch (see photo of old latches). One window was so bad that I stuck on foam for 30% of the window but had to remove it from the rest of the frame or the window wouldn't latch. That window is still tough to latch so I probably need to peel off more of the foam, higher up the frame.
I also investigated tubing insulation but didn't see any that would suit the problem. Hopefully I've missed something.
Is there some window insulation product that will compress when needed and fill gaps when needed?