True. Our building is 20 year old swiss one, mostly concrete, one would expect already good temperatures. Ground floor and first one are fine even now (26 is max it gets), but floor under roof is much warmer. 28 and more and I can't work mentally much, sweat just sitting, showers work for few mins. No AC would make it unbearable to WFH for example.

Ventilation during night is almost useless, there is no breeze these days the air is perfectly still. Open windows through the building and air doesn't change, just insects come.

Now typical proper 2-part ACs are forbidden here for residential buildings, and monolithic ones are not that effective. We bought a mix of this from midea last year - 2 parts, permanently connected by hose, and we put it out when needed and cover door to balcony. easily 25 max under roof at low rpms, so far so good (outside easily 35 in shade, >42C on balcony in afternoon/evening). Proper permanently installed 2 part AC would save some energy since we lose some cold via smaller gaps in door, but its frequent these well-meaning moves end up doing more damage than intended.