[pdonis]

It's not the heat, it's the humidity. For typical summer conditions in Dallas (even more so in, say, Houston or Brownsville), if I'm remembering the numbers from my time as an automotive HVAC engineer correctly, it takes 5 to 6 times as much energy to dehumidify the air as to cool it. And those are by no means the worst conditions on the planet: try southeast Asia or equatorial Africa.

It's true that you can claw some of that back from the fact that A/C can have a coefficient of performance greater than 1, but COP also gets worse (i.e., closer to 1, less of an advantage) as the conditions get more extreme.

[SoftTalker]

Yes, because dehumidification involves a phase change (water vapor to liquid) and the heat of vaporization is much higher than needed to effect a simple temperature change in dry air.