Zero energy AC units
 

Survivor groups in hotter and more arid areas with some form of water nearby could use this. A drop in air temperature from 50C to 36C is significant.

http://www.ant-studio.org/new-galler...8j1omv18tebcr6

That makes the great point that rather than making 1880s stuff again we're much more likely to see in The Morrow Project USA stuff that is now used by relief agencies in the 3rd world deployed.

Just as an observation, that isn't "zero energy" - it requires moving air and water, and if you don't have those conveniently in place then you will need energy to produce them. An interesting idea, but a niche solution.

Which is exactly why the warlord in his terracotta dwelling always has two of his "servants" drawing up buckets of water and working the fan.