Reverse cycle

A reverse-cycle air conditioner both cools and heats by literally running its refrigeration cycle in reverse, and it's the cheapest whole-home heating available in most of Australia.

Because it moves heat rather than generating it, reverse-cycle heating delivers 3–5kW of warmth per kW of electricity, far cheaper to run than resistive electric heaters and, increasingly, than gas. It's why "aircon" and "heater" are the same purchase in Canberra, Melbourne, Toowoomba and Dubbo, and why heating performance at low temperatures deserves a line in cold-climate quotes.