15 June

Have been running the reverse-cycle units (heat pumps in techno language) 24 hours a day this (cold) winter, as an experiment. You can see in the yellow circle that overnight, in a cold Lithgow winter, they use hardly anything. Between 0.5-1kW draw, all night. The bigger peaks are the jug, toaster and induction cooktop, making breakfasts. Once you get the house to a temperature its thermal mass helps to avoid the need for constant heating or cooling. This allows the heat pumps to operate in their most efficient range i.e. to do not much work at all. It helps to have double-brick, a lot of thermal mass. But in general heat pumps will always use less energy if you keep the inside temperature pretty constant, with half-decent insulation so you’re not just heating the backyard. As an obvious bonus, you get great comfort 24 hours a day.