IT'S MAGIC:

Relative to an electric fan heater or traditional electric hot water service, I calculate a heat pump can save 60-85% on energy costs, which is a similar range to ACT government estimates.

Comparisons with gas are tricky, as efficiencies and energy prices vary a lot. Typically, though, a heat pump costs around half as much for heating as gas. If, instead of exporting your excess rooftop solar output, you use it to run a heat pump, I calculate it will be up to 90% cheaper than gas.

Heat pumps are also good for the climate. My calculations show a typical heat pump using average Australian electricity from the grid will cut emissions by about a quarter relative to gas, and three-quarters relative to an electric fan or panel heater.

If a high-efficiency heat pump replaces inefficient gas heating or runs mainly on solar, reductions can be much bigger. The gap is widening as zero-emission renewable electricity replaces coal and gas generation, and heat pumps become even more efficient.

Heat pumps available today achieve 300-600% efficiency - that is, for each unit of electricity consumed, they produce three to six units of heat. Heat pumps can operate in freezing conditions too.

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