It's also that "it's hot only several days in Summer, why do we need Acs?" and then year over year Western and Central Europe is suffering from "unexpected" heat waves. What makes it worse is that residential buildings haven't been built for this kind of climate.

It's the dry air that makes people sick who aren't used to living with an AC, I see it in the office every year. I'd say Barcelona is right around the area where an AC makes sense, you have 2 months per year being a little annoying but nothing unbearable. Also, it still rains in summer.