Heat pumps are suitable for every climate zone in New Zealand, even the coldest, and they are the most efficient source of heating and cooling. Don’t buy crappy ones. New labelling makes it easier to compare models.
We always recommend heat pumps in our building designs or other projects we consult on. For single family homes, it’s usually just one heat pump and the smallest one you can buy. Because we design high performance homes where the heat doesn’t leak out, that heat pump is cheaper to run than a fridge.
An average 350-370 litre fridge costs around $110-$120 a year. In a 100 m2 Certified Passive House, heating uses 15 kWh/m2 per year (or less), so 1,500 kWh over the whole year. Using electric resistance heat would cost $375 each year. But if you use a decent heat pump (COP=3.5 for the geeks), it would be less than $107 for the whole year. All calculations assume electricity costs $0.25/kWh.
EECA is rolling out a new and much improved energy star rating and label for heat pumps. Compare a few of the name brands sold locally in your city. I’d advise buying a variable speed compressor unit (look for ‘inverter’) on the label.
Star ratings and energy used for heating (or cooling) are based on the test information of the heat pump at two outside temperatures at 7°C and 2°C (and 35°C for cooling). ECCA uses test information to determine the heat pump’s performance (heat output, and efficiency) across a range of climate temperatures.