I don't know about the impact of buildings - I've been at Sungei Buloh, McRitchie under the jungle canopy, Changi Village, even Pulau Ubin - nice open and breezy, no buildings - and the weather is still heat shock inducing within hours. Going out at night, it merely takes longer to get drenched, but it is still inevitable. I think you guys have the combination of more adapted genetics and 2 years of NS to shock whatever is lagging into adaptation. Even back then, LKY thought AC "changed the nature of civilization by making development possible in the tropics". Average temperature in the mid-20th century (no data before then) was around 26 vs 28.5 today, still pretty warm for long sleeves let alone a suit... what makes the difference is the steamy air, as your natural temperature control (evaporation) doesn't work in 100% humidity.It was not so hot back then. These places were near the harbour, had proper ventilation and there were much less people and more trees.