Home heating cost guide
Find the economic heat-pump and gas-furnace crossover
A dual-fuel thermostat should switch based on local energy prices and the heat pump’s actual cold-weather performance. National averages and blanket savings percentages cannot identify the right temperature for a specific home.
This calculator separates three questions: which fuel is cheaper at a given outdoor temperature, which system has the lower first-year operating cost, and whether higher equipment cost is recovered during the selected ownership period.
How to use this tool
Use delivered utility rates
Divide the full variable electricity or gas charge by billed kWh or therms. Keep unavoidable fixed charges separate.
Estimate delivered heat
Weather-normalize annual gas use or use a Manual J/load-model estimate rather than total household energy.
Enter certified performance
Use HSPF2 and two heating COP points from the exact outdoor unit and indoor coil combination.
Test price and incentive changes
Change escalation rates and enter only rebates confirmed for your installation date and location.
Economic switchover versus thermal balance point
The economic switchover temperature is where heat from the heat pump and furnace costs the same. HVAC professionals may use thermal balance point for the outdoor temperature where heat-pump capacity equals the building load. Those are different thresholds; capacity, comfort, defrost behavior, and utility demand rules can require an earlier switch even when the heat pump remains cheaper.
What changes the answer most
- All-in variable electricity and natural-gas prices
- Furnace AFUE and heat-pump COP at cold outdoor temperatures
- Whether eliminating gas heat also eliminates the monthly gas account charge
- Installed-cost difference after current state and utility rebates
- The home’s actual heating load and duct losses
Reading manufacturer COP data
Match the outdoor model, indoor coil or air handler, compressor stage, airflow, and temperature. Two points provide a transparent linear estimate, but a contractor should use the full performance table when programming a dual-fuel control.
Equipment sizing, low-temperature capacity, defrost, backup-strip operation, duct condition, demand charges, and safety are outside this cost model. Have a qualified HVAC contractor verify the load calculation and manufacturer performance data before changing a dual-fuel lockout temperature.
Sources and further reading
- DOE economic switchover guidance — Switchover COP formula and use of manufacturer performance data.
- DOE air-source heat-pump purchasing guidance — HSPF2 definition and lifecycle cost guidance.
- EIA energy unit conversions — One kWh equals 3,412 Btu and one therm equals 100,000 Btu.
- IRS energy-credit termination FAQs — Section 25C is unavailable for property placed in service after 2025.
Frequently asked questions
What COP makes a heat pump cheaper than natural gas?
It depends on electricity price, gas price, and furnace AFUE. The required COP shown above is the exact marginal-cost threshold for the entered rates, including optional furnace blower electricity.
Should the monthly gas customer charge affect switchover temperature?
No. A dual-fuel system pays the charge regardless of which appliance runs that hour. The lifecycle comparison includes the charge when a strategy keeps gas service and removes it only when you select that gas service is removed.
Is HSPF2 the same as COP?
No. HSPF2 is a seasonal Btu-per-watt-hour rating. Dividing it by 3.412 gives a seasonal COP approximation. Outdoor-temperature COP values are used separately for the dual-fuel crossover.
Does the calculator include federal heat-pump tax credits?
The default is zero because the federal Section 25C residential credit is not allowed for property placed in service after December 31, 2025. Enter current state, tribal, utility, or other confirmed rebates manually.