Heat Pump Savings Calculator

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Upgrade preset:

Choose a starting case, then replace every value with bill and bid data.

Current heating fuel:

Use the fuel and unit shown on the space-heating bill or delivery record.

Annual fuel use:

This is purchased energy before current-system efficiency losses.

Current efficiency:

{{ formatNumber(current_efficiency_pct, 1) }}%

The model applies this percentage to purchased fuel heat content.

Current fuel price:

Use a recent seasonal bill average or contracted delivery price.

${{ fuelPriceUnit }}

Heat pump efficiency basis:

The chosen basis determines the modeled heat-pump electricity.

Seasonal COPHSPF2

Seasonal COP:

{{ formatNumber(hp_cop, 2) }} COP

Use a conservative climate- and backup-heat-aware seasonal value.

COP

HSPF2 rating:

The model converts Btu/Wh to an equivalent seasonal COP.

Btu/Wh

Electricity price:

{{ formatMoney(electricity_rate) }}/kWh

Replace the USD sample with the marginal rate on the project bill.

$/kWh

Installed project cost:

Confirmed incentives:

The model subtracts this amount from installed cost for simple payback.

Current cooling electricity:

kWh/yr

Cooling electricity reduction:

Annual maintenance offset:

$/yr

Annual backup heat cost:

$/yr

Planning horizon:

years

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Heating bills compare poorly across fuels because therms, gallons, and kilowatt-hours describe purchased energy rather than useful heat delivered indoors. A fair heat-pump comparison first converts the existing fuel to heat content, applies the current system’s efficiency, and then asks how much electricity a heat pump would need to deliver the same seasonal heat.

Seasonal efficiency is the pivotal assumption. Coefficient of performance (COP) expresses useful heat delivered per unit of electricity. Heating Seasonal Performance Factor 2 (HSPF2) is a laboratory rating in Btu per watt-hour; it can be converted to an equivalent seasonal COP for this estimate. Actual seasonal performance still depends on climate, sizing, controls, defrost, duct losses, and backup heat.

Current heating cost: Annual fuel use multiplied by its price, before any heat-pump comparison.
Delivered heat: Fuel heat content multiplied by the current system efficiency.
Operating savings: Current annual heating cost minus modeled heat-pump heating cost, with optional cooling, maintenance, and backup-heat adjustments.
Simple payback: Net installed cost divided by positive annual savings, without financing, discounting, price escalation, or equipment replacement.

Fuel and electricity prices should come from bills that match the same home and a representative season. For electricity, the marginal rate that changes with extra use is more useful than dividing a whole bill by kilowatt-hours when fixed charges will not change. Confirmed incentives reduce the project cost only when the selected equipment, address, and installation date actually qualify.

Lower operating cost does not guarantee a good project. Comfort, cold-weather capacity, electrical or duct work, service life, maintenance, financing, and the condition of the existing system can outweigh a short payback estimate. A single result should be tested with conservative efficiency, rate, and backup-heat assumptions before comparing bids.

How to Use This Tool:

Match one full year of heating use with a proposed heat pump and the costs that would change after installation.

Choose Current heating fuel and enter Annual fuel use. Use therms, gallons, or kWh exactly as shown for the selected fuel.
Enter Current system efficiency and Current fuel price. Use a defensible seasonal efficiency, not a combustion-efficiency label that ignores distribution losses.
Choose Seasonal COP or HSPF2 and enter Electricity price. Prefer a climate- and backup-heat-aware seasonal COP when a contractor or load model provides one.
Enter Installed project cost and Confirmed incentives. Keep the project scope consistent across bids, including equipment, electrical work, ducts, controls, permits, and removal.
Open Advanced for material adjustments. Add cooling savings, maintenance change, annual backup heat cost, and a planning horizon only when each value has a clear basis. Then compare annual savings, break-even values, and horizon net savings.

Interpreting Results:

Start with cost per delivered MMBtu. It places the current system and heat pump on the same useful-heat basis. The electricity-rate and efficiency break-even values show how far the assumptions can move before modeled heating cost becomes equal.

Strong payback means positive savings and payback at or below 7 years. Moderate payback is above 7 through 12 years, and Slow payback is above 12 years. Zero or negative annual savings produces no positive payback. These labels describe this simple cash model, not project suitability.

Technical Details:

The energy balance holds delivered useful heat constant. Fuel-specific heat content converts the existing annual use to Btu, current-system efficiency removes estimated losses, and seasonal COP converts that useful heat to heat-pump electricity.

Formula Core:

The model uses full precision internally and rounds reported numeric results to six decimal places.

\begin{aligned} H & = \frac{U B η}{10^{6}} \\ E_{hp} & = \frac{U B η}{3412.142 COP} \\ S_{annual} & = (U p_{f} - E_{hp} p_{e}) + E_{cool} r_{cool} p_{e} + M - A \\ P & = \frac{\max (0, C_{installed} - Incentives)}{S_{annual}} \\ S_{horizon} & = Y S_{annual} - \max (0, C_{installed} - Incentives) \end{aligned}

Symbols used in heat pump savings equations
Symbol	Meaning	Unit
U, B	Annual fuel use and heat content per fuel unit	fuel unit/yr; Btu/unit
η	Current efficiency entered as a decimal	ratio
H	Delivered useful heat	MMBtu/yr
E_hp	Heat-pump heating electricity	kWh/yr
p_f, p_e	Fuel price and electricity price	currency/fuel unit; currency/kWh
E_cool, r_cool	Current cooling electricity and reduction fraction	kWh/yr; ratio
M, A	Annual maintenance offset and annual backup-heat cost	currency/yr
P, Y	Simple payback and selected planning horizon	years

When HSPF2 is selected, equivalent seasonal COP equals HSPF2 ÷ 3.412142. The equation is dimensionally useful for this annual estimate, but a rating-point conversion does not reproduce climate-bin performance or a detailed load calculation.

Fuel heat content constants used by the savings calculation
Fuel	Heat content
Natural gas	100,000 Btu/therm
Propane	91,452 Btu/gal
Heating oil	138,500 Btu/gal
Electric resistance	3,412.142 Btu/kWh

Break-even electricity price is the price at which heat-pump cost per delivered MMBtu equals the current system’s cost. Break-even COP and HSPF2 solve the same equality for efficiency. Annual prices and performance remain flat across the horizon; no discount rate or escalation is applied.

Accuracy Notes:

Use weather-normalized or representative fuel use when the latest year was unusually mild, severe, vacant, or affected by another heating change.
Confirm design heat load, low-temperature capacity, backup controls, duct losses, and electric service requirements with qualified contractors.
Simple payback excludes financing, discounting, energy-price changes, equipment life, replacement, and residual value.
The result is an educational estimate, not financial, tax, or engineering advice.

Worked Examples:

Electric resistance replacement

Replacing 12,000 kWh/yr of resistance heat at $0.16/kWh with a seasonal COP of 3.2 reduces modeled heating electricity to 3,750 kWh/yr. Annual savings are $1,320. With a $9,000 project and $1,500 confirmed incentive, the $7,500 net cost has a 5.68-year simple payback.

Oil conversion with a long payback

For 550 gallons of heating oil at 82% efficiency, a 9.2 HSPF2 heat pump, cooling and maintenance offsets, and $240/yr of backup heat, modeled annual savings are about $782.59. A $13,500 net project cost takes 17.25 years to repay and remains about $1,761 negative after a 15-year horizon.

References:

British thermal units and fuel conversion factors, U.S. Energy Information Administration.
Purchasing Energy-Efficient Residential Air-Source Heat Pumps, U.S. Department of Energy.
Heat Pump Systems, U.S. Department of Energy.