system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does it cost more to run air conditioning in the summer than it does to run heating in the winter?

Curious, because our electricity bills are always seem to be ridiculously high in the summer, when AC is running. And we don't have any other provider of heat like gas or fire.
gpt
Heating is more efficient than cooling; at a minimum, a working machine produces heat. If an air conditioner is producing heat as well as cold air, that's reducing its efficiency. If a heater is producing heat as a byproduct, well... that's sort of what it's supposed to do.