@0xabad1dea @Newde there's some heat inertia. My fifty year old apartment peaked at 29 °C yesterday, 5 degrees lower than outside at the time.

Unfortunately the inertia also means it takes forever to cool down even with a cross-breeze. I've half-seriously considered mounting cooling fins on the walls.

I wonder if spraying water on the walls (for evaporative cooling while the windows are open) is a terrible idea or a *really* terrible idea.