I don't know, the need to air conditioning is kinda relative anyway, and it creates a lot of Co2 as well, thereby contributing to the global warming problem.

A few years ago I've been in an old monastery, almost daily, in both summer and winter. The summer was good, albeit with a window open. Not as good as airco, but good.

However the gas costs in winter were insane, from what I heard it was in the hundreds of thousands of EUR.