The proportion of homes using air conditioners is rapidly increasing in hot climates. But this is unsustainable, in the long run, from an environmental standpoint.
Air conditioning (especially central AC) is already an important cause of CO2 emissions, and should be used selectively.
What to do then?
The answer: well designed homes, properly sited, using adequate cooling features and strategies - based on high levels of shading and ventilation - do not need much air conditioning. Only in some very hot-humid climates air conditioning becomes particularly advantageous; other alternatives do not offer the same degree of comfort.
Anyway, in most climates, with the right cooling strategies, people can get by with little air conditioning, or no air conditioning at all.
Here, in this page, we list a few alternatives to air conditioning, and also some ways of reducing its use in very hot climates. Just do not forget the basics of home energy efficiency for cooling (see table below).
Hot Dry Climates: Energy Saving Methods
In hot dry climates consider evaporative cooling, that is, the use of pools, ponds and water features close to your house. These water features, properly planned and shaded, can create convective breezes and cooler air.
Consider also evaporative coolers and whole-house fans: they consume a small fraction of the power consumed by air conditioners. They can provide very significant energy savings.
Humid Climates: Energy Improvement Strategies
In hot-humid regions, natural cooling strategies rely on very high levels of shading (all over the walls, the roof, and around the house), fly roofs (to shade the walls and windows) and ventilation, in favorable periods.
Shading the outdoor areas around the house with trees and vegetation or by using structures like pergolas and verandas is very important to lower ground and outside air temperatures and, ultimately, the indoor temperatures.
Narrow homes (with single room depth) with shaded openings will maximize the cross ventilation benefits; open room layouts, allowing unobstructed ventilation paths are very important...
Upper openings (clerestory windows…), ceiling fans and whole-house fans are also crucial for some periods - like selective use of air conditioners, in very harsh climates. See, on this issue: Air Conditioners in Hot Climates.
In very hot climates, where natural ventilation is difficult to implement, consider induced ventilation techniques for energy savings. They may involve structures like thermal chimneys, under-grade air chambers and trombe walls.