I would add as a contributing factor for the need to AC a modern house/building is the change in building philosophies, where everything now has to be buttoned up so air-tight that people could suffocate inside. In the pre-electricity days, houses were designed to naturally ventilate themselves. I was in an old mansion once, and they had interior hinged windows at the top of every wall that could be adjusted to allow airflow between rooms. No AC, and it was bearable inside during a warm summer day thanks to simple convection.
Ironically, I just finished putting the finishing touches on a DIY central air installation today. On a hot day, the whole house is only using 0.85 kWh per hour with dew forming outside on the double-pane windows.
The unit that I chose also had the heat pump feature as a $100 add-on, which seemed like cheap insurance even if only as a backup to the hot water oil boiler. I would never have considered a heat pump in place of a traditional boiler/furnace, but will let the system run during the fall to see if I can project winter electric power costs versus running the oil boiler. Supposedly, it should be 2.0-2.5 times the cooling cost to heat with it.....