Air conditioning: https://economictimes.indiatimes.com/magazines/panache/no-ac...

Refrigerator would be a traditional root cellar such as my uncle had --- he was also fortunate to have a spring on his property which he encapsulated in a rock structure which was a wonderful place to be on a hot summer day/evening.

If you don't have AC but do have a refrigerator, you can build a DIY AC using a box, bottles of frozen water and a fan. There's YouTube tutorials on how to do it.

I have friends who use it in their apartment which doesn't have AC and doesn't allow installation of one.

Yes, an air conditioner can be made as follows.

1. Identify a locally viable deciduous tree species.

2. Plant this species on the afternoon aspect of the sun in your location. So for northern hemisphere plant to the southwest. For southern hemisphere plant to the northwest.

3. Enjoy shade in summer and sun in winter, plus cleaner air.

Another option depending upon your architecture is to take advantage of forced air within a roof cavity. Buy a large diameter fan with an electronic control, install at apex, and set it to operate when the temperature exceeds a certain point. This will result in a house wide temperature drop with no need to expend $$$ setup plus dollars per hour per room on air conditioning.

Another option is simply shading. One of the simplest and most traditional approaches here is the drop awning. A drop awning consists of a retractable material expanse which can render a building surface in shade and thus promote rapid air movement and cooling in the hottest periods.

Two final options include internal forced air: passive variant (open all the windows and doors) or active variant (ceiling fan, solar works) and insulation or thermal mass.