Heat Pump Savings Calculator NZ
This calculator works out how much you could save on heating costs by switching from plug-in electric heaters to a heat pump, and how long the install would take to pay for itself. Heat pumps use far less power than plug-in heaters to produce the same warmth, because they move heat rather than generate it, but that saving has to be weighed against the upfront install cost. You enter the heat you need delivered per day in kilowatt-hours, how many days a year you run the heating, your power price per kilowatt-hour, the heat pump's coefficient of performance (COP), and the total install cost. The calculator then returns your estimated annual saving, your current plug-in heating cost, the equivalent heat pump running cost, and the payback period, worked out by dividing the install cost by the annual saving. Use it to check whether a heat pump quote stacks up before you commit, or to compare usage patterns to see where a heat pump pays off fastest. The default figures show a typical living-room scenario paying back in five to six years. Because heat pump efficiency changes with outdoor temperature and power prices move over time, treat the results as an indicative estimate rather than an exact forecast, and use your own power price and realistic heating hours for the most accurate picture.
Assumes you currently use plug-in electric heating (one unit of power per unit of heat). The heat pump delivers the same heat using less power, by its coefficient of performance. Real efficiency varies with temperature. Power prices change, so use your current rate. Estimate only.
How it works
The calculator works out the heat you need over the season, then the cost of delivering it with plug-in electric heating, which uses one unit of power per unit of heat. The heat pump delivers the same heat using less power, dividing by its coefficient of performance. The difference is your annual saving, and dividing the install cost by that saving gives the payback period.
Worked example
Delivering 18 kWh of heat a day for 150 days at 28 cents costs about $756 with plug-in heaters. A heat pump with a COP of 3.5 delivers the same heat for around $216, a saving of about $540 a year. A $3,000 install pays back in roughly 5 to 6 years.
Related calculators
- Home Heating Cost Calculator: compare heating.
- Electricity Cost Calculator: appliance costs.
- Solar Panel Payback Calculator: solar savings.
- Power Plan Comparison Calculator: compare power plans.
- Room Heat Pump Sizing: what kW your room needs.
- Warmer Kiwi Homes Grants: the background to this calculation.