Geothermal Savings Calculator

This calculator prices out a full year of heating and cooling twice — once through a geothermal heat pump, once through your current conventional system — and reports the gap. On the geothermal side, both annual heating and cooling loads (in BTU) are converted to kWh (dividing by 3,412 BTU/kWh) and then divided by the geothermal COP, since a heat pump multiplies each unit of electricity into several units of heat moved; both are priced at your electricity rate. On the conventional side, heating cost depends on which fuel you select: gas heating converts BTU into therms (100,000 BTU per therm) divided by furnace/boiler efficiency (AFUE) and prices it at your gas rate, while electric heating converts to kWh divided by that same efficiency and prices it at your electricity rate — so switching the fuel selector changes both the unit conversion and which price you're charged.

Conventional cooling always uses the EER rating you enter (BTU divided by EER × 1000 gives kWh) priced at electricity rate, regardless of the heating fuel choice. Annual savings is simply conventional cost minus geothermal cost, with the percentage and monthly figures derived directly from that difference. The result is only as good as the efficiency and COP numbers you supply — a geothermal COP of 4 assumes a well-designed loop and correctly sized equipment, and real-world COP degrades if the ground loop is undersized or the ground temperature is colder than the system was designed around, which this calculator has no way to check on its own.