[simplyinfinity]

European windows open sideways not up and down. So we can't just stick an ac unit on the window.

[tpm]

Yes you can (I've got one), there are various window seals to adapt to that or you can dyi too. The noise etc make it a temporary solution at best but it's possible.

[simplyinfinity]

I've also used portable AC inside my home, it was horrible, a lot of heat creeps in due to bad insulation for the heat exhaust pipe, also creates vacuum since it exhaust air, which in turn sucks in more hot air

[asdff]

You don't stick a portable AC unit in the window. The unit sits inside. You just run vent hoses out the window for the compressor.

Opening sideways also shouldn't matter for a casement AC unit.

[zarzavat]

Portable ACs are borderline scams because the hot side is inside the room it's trying to cool, among other reasons[0].

[0] obligatory TC rant: https://youtu.be/_-mBeYC2KGc