I live in a pretty hot climate, but it’s only really unbearable at times due to shoddy building and bad urban planning. Even then, summer can be difficult.
I can’t imagine what it’s like on the equator, especially in dense urban centres. What’s Mumbai, Bangkok, or Singapore like at the height of the wet season?! How do millions of people function day to day?
For those who live in rural yet areas, Trees and streams are your friends. We ensure at least one fruit tree and another a non edible tree is on the property depending on the size of the property. This is the cheapest way of creating shade so much so you create a micro-climate for yourself. while everyone is worried about the heat, your environ is considerably cooler during the hot season and colder in the wet rainy period.
Some do incorporate airconditioning system if the structure of the house is not well designed for natural cooling process to take place.