Heat Pump Sizing Calculator

Heat pump running costs in New Zealand depend on the unit's efficiency (COP), the size of the space being heated, your electricity tariff, and how many hours per day it runs. As a rough guide, a typical 2.5 kW heat pump with a COP of 4 uses approximately 0.6–0.7 kW of electricity per hour, costing about $0.20–0.25/hour at an average rate of 35 cents/kWh. For a 6-hour-per-day heating season use, this equates to approximately $1.20–1.50/day or $180–225 over a three-month winter. Larger units (5–7 kW) for whole-home heating can cost $2–4/hour. Running costs can be reduced by using a timer, setting a consistent temperature, and ensuring the home is well-insulated. Source: EECA Energywise — Heating (energywise.govt.nz).

The Coefficient of Performance (COP) is a measure of a heat pump's efficiency — it tells you how many units of heat energy the heat pump produces for every unit of electrical energy consumed. For example, a heat pump with a COP of 4 produces 4 kWh of heat for every 1 kWh of electricity used, making it 400% efficient. Modern New Zealand heat pumps typically have COPs ranging from 3 to 5 under standard test conditions, though real-world performance varies with outdoor temperature (COPs drop in very cold weather). By comparison, a standard electric heater has a COP of 1 (100% efficient). Higher COP means lower running costs: a heat pump with COP 4 costs roughly one-quarter of what an electric bar heater costs for the same heat output. Look for the Energy Star rating when purchasing. Source: EECA Energywise (energywise.govt.nz).

New Zealand electricity prices vary by region, retailer, and plan type. As of 2024–25, the average residential electricity price is approximately 30–38 cents per kilowatt-hour (kWh) including GST, with the national average around 33–35 cents/kWh. Prices are generally higher in the South Island (particularly Westland and Otago) and lower in hydro-generation-rich areas. Auckland and Wellington tend to sit near the national average. Daily fixed line charges add $1.50–2.50 per day regardless of usage. Some retailers offer time-of-use pricing with cheaper overnight rates (e.g., 15–20 cents/kWh) suited to EV charging. New Zealand's electricity is predominantly renewable (around 85% hydro, wind, and geothermal), though wholesale prices fluctuate seasonally. Comparing plans via Powerswitch (powerswitch.org.nz) can reduce bills by $200–600/year. Source: Electricity Authority — Powerswitch (powerswitch.org.nz).

Heat pumps are widely regarded as the most cost-effective heating option for most New Zealand homes. Compared to other common heating methods: a standard electric resistance heater (bar heater, panel heater) has a COP of 1, so running costs are 3–5 times higher than a heat pump. Bottled LPG heating costs roughly $3–5 per hour for a typical portable heater — more than most heat pumps. Natural gas (reticulated) central heating costs approximately $2–4/hour but is only available in some NZ cities and involves connection and appliance costs. Wood burners offer cheap fuel but require ongoing wood supply and don't heat specific rooms efficiently. Heat pumps also provide cooling in summer at low cost. The NZ government's Warmer Kiwi Homes programme provides subsidised heat pump installations for eligible low-income homeowners. Source: EECA Energywise — Heating Comparison (energywise.govt.nz).