Moneymatters wrote: ↑Fri Nov 05, 2021 4:01 am...
We had curtains then switched to blinds that fit neatly inside the window frames. Great improvement on heat retention in winter. Which is hardly surprising as you can see them bulge inward as air flows through the frame of a closed window.
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We have huge windows in one room, the whole wall--over five meters wide and 180cm tall (two large openings, two window 'panels' in each). Yes, that's
a lot of window framing, relying on simple flaps for seals. They're double-glazed, but old style, and the casing & frames are just aluminum.
One simple trick that makes a big difference is to tape the edges. I've done this outside on ours, using electrical tape (vinyl) that's 20-30mm wide. You'll need a tall enough ladder, but this can then be done for peanuts, a couple rolls of tape. I do the left and right verticals, and not the middle (where the panels meet and they lock). And not the top (hard to reach), and I think the bottom should be left open just in case for drainage. Obviously, this effectively locks the windows shut till you remove the tape.
There's a second thing I've done, tho I skipped it last year. Due to the design of the framing, there's a small 'lip' top and bottom, about 10-12cm in from the glass. I've added verticals on the walls at each end that match up with those lips. Using double-sided tape, and a seemingly endless roll of 1 mil plastic from the home center, I can add what is effectively a third pane with good air cushion.And being taped up all round, it seals almost perfectly--when the wind blows it billows in/out a little as you described.
The plastic is not clear, almost but not really. So it destroys any view, and it does dim what light that enters a little. It's 'clearer' or brighter than sheer curtains, not by much, but it does so much more than those curtains.
With energy prices where they already are, I plan to do this soon (the tape has stayed on all summer), and I'll try to take some before/during/after pics and do a writeup here on the forum.