It is true that heat is easier to generate. Berlin is considered mild while Phoenix is considered very hot. They just happen to have the same temperature deltas

It is true that heat is easier to generate. Berlin is considered mild while Phoenix is considered very hot. They just happen to have the same temperature deltas. On the whole, the world spends many, many times more energy heating living spaces than cooling them. The coldest cities people live in just have much larger room temperature deltas than the hottest.