Not an expert on the subjet, but what I saw is this: old houses and churches (400+ years) with big stone walls tend to be rather cool in summer (my parents hous

Not an expert on the subjet, but what I saw is this: old houses and churches (400+ years) with big stone walls tend to be rather cool in summer (my parents house ground floor always stay under 25°C when properly used, even with temperatures reaching 40°C outside) and have little temperature fluctuation overall (a piano, which is very sensitive to that and need yearly tuning in most places, can stay tuned for 10 years without intervention). I suspect the biggest factor is insulation due to having having a lot of mass that doesn't easily change temperature, but again I'm not an expert. Incidentally, you cannot have it all: this architecture is not cheap, not fast, and isn't designed to withstand earthquakes or floods. But you'll never need air conditionning.