A radiant floor is just a heat transfer system that still needs a hot/cold source. Evaporative coolers (aka swamp coolers) are really the modern day equivalent.
Swamp coolers only work when the outdoor air is quite dry (Arizona, Nevada, New Mexico). The resulting indoor air is very humid. Swamp coolers cannot make a big difference in temp. In NM they are perfect because the air is dry (too dry for comfort, IMO) and you only need to lower the temp by a small amount. So the resulting indoor air quality in NM is perhaps the best in the world for those who like ~65—70% humidity. A lot of swamp coolers in AZ have been replaced with A/C because the city temps have increased¹ to a point where swamp coolers cannot make a sufficient temp decrease. So I wonder if an AZ residents kept their swamp coolers going & added A/C. Note that A/C dries the interior air, so I suspect the swamp cooler might actually be make the A/C work harder in that scenario. If anyone knows something concrete about this I’d be interested in hearing it.
① One theory on the temp increase in AZ cities is simply more and more concrete covering the ground (roads, parking lots, driveways), less soil and vegetation. This means rainwater is drained off instead of having the large scale evaporative cooling effect of soil & vegetation absorbing water temporarily until it evaporates. IMO one correction (apart from reverting parking lots to gardens) is to get roofers installing vegetated rooftops. I really don’t understand why #vegetatedRooftops are nearly non-existent in the US. Pick any city and call every single roofing company in the region, and most likely not a single one of them can do #vegetatedRoofs.
Ancient Iran had air conditioning (lemmy.world)