> But let's not forget that energy is also on average a lot more expensive in Europe than in the US. The cost plus environmental concerns, which seem to fair less high in the public conscience on the other side of the Atlantic, have also been reasons why people were not keen on AC units in the past.

The price of energy in Europe is largely determined by taxes and policy costs. Gas is mostly unencumbered. Electricity could be as well. It's a political choice to make electricity expensive.

Furthermore, given that many Europeans couldn't care less about the negative externalities of gas heating, it's very hard to argue that this is a major concern for AC, especially when AC is already mainstream in cars.