When I lived in Cambridge, MA, my (relatively new) apartment building was of the type that had to be switched between heating and cooling for the entire building. Most of the time, this was good enough, but there was the occasional really warm day in winter -- and cool day in spring or fall -- where there was no relief to be had from the heat or the cold.

As for the idea that Europeans are more environmentally conscious? I disagree. They might be shy to turn on the air conditioning once the weather heats up, but they don't seem to be shy about turning on the heat during the winter!

I spent one NYE in Spain, and nearly every building I would go into would have the heat turned up to at least 70-75 degrees. If Europeans were so environmentally conscious, why wouldn't they leave the thermostat set at an energy-saving 60 during the wintertime? The ironic part is, even after removing my coat, hat, and gloves, I would still sweat because the heat was turned on so high, whereas the Spaniards seemed quite content to wear their hats, scarves, and winter coats inside.

I suspect that Europeans simply favor hot weather more than Americans do, so the lack of a/c (but apparently not the lack of heat) is no big deal to them. Kind of like how US-based airlines tend to keep a cooler cabin temperature than Asia-based airlines do.