Electricity guide · New Zealand
Heat Pump Heating vs Cooling Cost NZ
Compare the electricity cost of using a New Zealand heat pump for winter heating and summer cooling, including efficiency, temperatures, settings and runtime.
Reviewed 26 August 2026
Reviewed by KiwiTools editorial team — NZ energy researchers using Electricity Authority and EECA sources
General planning information. Electricity prices, time bands, appliance performance and solar export terms vary by address, retailer, installation and usage.
Key points
Heating and cooling cost depend on conditions
The same heat pump uses its refrigeration cycle in opposite directions for heating and cooling.
Electricity use depends on the indoor-outdoor temperature difference, humidity, efficiency, thermostat and runtime.
Compare measured input and hours for each season instead of assuming the nameplate output is continuous consumption.
Why one heat pump has several running costs
These are scenarios, not label claims. Outdoor temperature, humidity, sizing, filters and set point change real electrical input.
| Check | Electrical input | Hours | Cost at 30c/kWh |
|---|---|---|---|
| Mild-day cooling | 0.7 kW | 6 | $1.26 |
| Hot-day cooling | 1.2 kW | 6 | $2.16 |
| Mild-night heating | 0.9 kW | 6 | $1.62 |
| Cold-night heating/defrost | 1.6 kW | 6 | $2.88 |
The same set point does not create the same workload
Cooling a mild room from 25°C to 22°C can be easier than heating a cold house from 8°C to 22°C. Outdoor temperature, sun, humidity, insulation and air leakage decide how hard the compressor works.
That is why “my heat pump is rated at 1.2 kW” cannot predict every hour. Inverter units ramp up, ease back and sometimes stop.
Heating can carry a defrost penalty
In cold, damp conditions an outdoor coil can frost. The unit temporarily reverses operation to clear it, reducing delivered indoor heat and using energy during the cycle.
A few defrosts are normal. Constant cycling, poor drainage or weak heating deserves filter checks and professional assessment rather than a higher thermostat setting.
Related: heat pump vs electric heater cost Related: peak off peak electricity rates Related: calculate electricity cost from watts
Comfort settings beat on-off folklore
Use a moderate set point, close doors to unused areas and clean filters. Letting the room become extremely cold and then demanding 28°C can produce a long high-output run.
Whether leaving it on is cheaper depends on heat loss and time away. For a well-insulated room and short absence, steady control may suit; for a draughty home left empty all day, heating nobody is hard to justify.
Frequently asked questions
Is heat-pump cooling expensive in NZ?
It depends on input power, runtime, temperatures, humidity and the power rate. Calculate a summer scenario using realistic hours.
Does cooling use the heat pump backwards?
A reverse-cycle heat pump changes refrigerant flow to move heat from indoors to outdoors.
Can I use the heating output kW as electricity input?
No. Output capacity and electrical input are different; use input power or measured energy.
Why does cost change on very cold days?
Efficiency, heating demand and defrost operation can change as outdoor conditions become more demanding.
Put the guide into practice
Continue with related KiwiTools calculators
Test your own numbers, compare scenarios and return to the guide to check assumptions and limitations.