Geothermal Heat Pump Calculator
A Heat Pump Moves Heat Instead of Creating It
Electric resistance heating converts electricity to heat at essentially a 1:1 ratio — one unit of electrical energy in, one unit of heat out. A geothermal heat pump instead moves existing heat from the relatively stable temperature of the ground into a building, which means it can deliver several units of heat for every unit of electricity it consumes. That multiplier is the coefficient of performance, and it's the whole reason geothermal systems cost less to run.
The Formula
Savings vs Resistance Heating = (1 − Input / Output) × 100
COP (coefficient of performance) is the ratio of heat delivered to electrical energy consumed. A COP of 3.8, for example, means 3.8 units of heat are delivered for every unit of electricity used.
Where This Is Useful
- Sizing a geothermal system — work out the heat output a given electrical input will actually deliver for a specific unit's rated COP.
- Comparing heating technologies — quantify the running-cost advantage of geothermal over resistance heating (or a lower-COP air-source heat pump) for the same electrical input.
- Estimating operating cost — heat output divided into a building's heating load gives the runtime needed, which can be converted into an energy cost.
Worked Example
A geothermal system with 5 kW of electrical input and a coefficient of performance of 3.8:
| Electrical input | COP | Heat output | Savings vs. resistance heating |
|---|---|---|---|
| 5 kW | 3.8 | 19.00 kW | 73.7% |
Typical residential geothermal heat pumps have a COP in roughly the 3 to 5 range, though the exact figure depends on ground temperature, system design, and manufacturer specifications — always use the rated COP for the specific unit.
How to Use This Calculator
- Enter the Electrical Input in kilowatts.
- Optionally enter the Coefficient of Performance — defaults to 3.8 if left blank.
- Select Calculate to get heat output and the percentage energy savings compared to resistance heating.
Related Calculations
Compare against direct electrical generation options with the Solar Panel Output Calculator, or check the cost of storing surplus generation with the Energy Storage Cost Calculator.