Portable Air Cooling

But only if the external ambient air is colder than inside those rooms.

Chris

Many thanks for all the replies, a lot to think about. It seems to me sash windows are ideal for making an enclosure, Velux and side opening windows not so easy.

And I do realise “ye cannae change the laws of physics”, thank you!

Absolutely. My portable AC was delivered a week ago. I think I have finally got it sorted for a tilt/turn window. I'm going for side opening with a wooden strip at the bottom to (a) keep it closed (b) block the outside air. Side is done with the kit that came with it (meant for a wide sash window). Top with Dacron fabric attached with Velcro.

We shall see.

I lived in the 'States for a while and slot-in-sash-window AC units were the norm in the cheap places I stayed - they used to keep them going with seemingly no thought about cost. Or indeed insulation - one place I stayed for about 3 months was basically a wooden shed, with 2 window mounted AC units.