AC is not only temperature control. Running water through the walls or evaporation cooling only work in moderately dry climates but will not help much in humid climates. Cooling the walls will just lead to condensation and wet walls. There's certainly a lot that can be done without AC, but humidity control is required in some regions of the world.
> The eccentric Roman emperor Elagabulus sent slaves to bring snow down from the mountains and pile it in his garden, where breezes would carry the cooler air inside.
Clay for the win. Even using a very thin clay based upper layer does incredible things to the room climate.
Historically most refrigerants have had "issues" when leaked either environmental or being toxic or otherwise it minimizes danger to keep as little as possible. Even if we could afford to use 1000x as much refrigerant with a central compressor station, it would be bad for the environment to use it that way.
You can move a huge amount of heat with water pressurized to merely 14 psi or so, but I have a puron aka R-410A conditioner at home and that dude runs near 400 psi on a hot day and its difficult to run miles of high pressure pipe.
I'm not sure bigger compressors are that much more efficient than smaller compressors, taking into account the environmental and economic expense of the pipes.
From an engineering standpoint its cheaper safer and less environmentally destructive to push kilowatts thru copper wire than push high pressure expensive refrigerant thru long high pressure pipes if all other things were equal which they mostly are.
For a long while, Stanford had an underground reservoir of ice for even better cooling (freeze ice at night when electrical prices are low, melt off during the day) http://web.stanford.edu/dept/news/news/1999/april21/iceplant...
The heat version of it is very common here in Sweden (for towns bigger than, say, 10k people) and it is a lot more efficient (and therefore, cheaper) than having heating units in the different buildings. We even have bigger data centers selling their spare heat from their cooling back to the heating systems.
Very large building-sized boiler and chiller plants served each half of my campus (probably less than a square mile in total). I'm not sure it would work at city scale.
Temperature control in buildings is 100% architecture and technical add-ons like AC are a poor choice. Look at termites how they use architecture to cool their hives.