Fairly uncommon in homes (although I wouldn't go as far as the sibling comment that it's only for very upscale homes—I know plenty of people who are getting equipped). Because the unit has to be outside, there are many historic buildings where you can't install AC. It's less of a problem in other parts of France.

Businesses open to the public and offices almost universally have AC, though, except maybe for mom and pop shops, so you definitely can go to the mall or the movies to get some fresh air.