Yep. The architecture is fundamentally not capable of dealing with the heat. I moved from Sydney to Germany a few years ago and 30°C has gone from being perfect

Yep. The architecture is fundamentally not capable of dealing with the heat. I moved from Sydney to Germany a few years ago and 30°C has gone from being perfectly fine to abject misery, long before air conditioning comes in to the equation. In Australia we have houses built with sizeable gaps to allow the frames to warp with the heat, while also allowing air to easily flow in and out of the building. Windows are single-glazed. Exactly what you don't want in a German house, in other words. In Germany the houses are heat traps and the focus has largely been to conserve energy in winter time (and rightfully so). I've had doors here which stop closing smoothly in the summer because of the slightest warping, the gaps are so tiny. Houses are often air-tight, and the external walls are half a meter thick due to the hefty insulation. All windows are at least double-glazed, one place I've stayed was triple. New German builds using the Passivhaus specification are generally pretty good as they have constant machine-generated airflow at a set temperature, but as far as I am aware, this specification can only be built new - it's not possible (within reasonable cost) to retrofit an older house to the new specifications. For those, air conditioning seems the only reasonable option moving forward.