FUEL LOAD HP NOW HP {{ stageCostRatioLabel }}
Start from a common retrofit case, then edit the actual bill and bid values.
The calculator converts this fuel into delivered heat before comparing the heat pump.
Enter only the fuel used for space heating when the bill also includes cooking or water heating.
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{{ currentEfficiencyDisplay }}
Efficiency converts purchased fuel into useful heat delivered indoors.
%
Use recent bill averages or contracted delivery price for the same season.
$ {{ fuelPriceUnitLabel }}
The selected basis drives the heat-pump electricity estimate.
{{ heatPumpCopDisplay }}
Use a conservative seasonal value for your climate and backup-heat strategy.
COP
The draft converts HSPF2 to seasonal kWh from delivered heat.
Btu/Wh
{{ electricityPriceDisplay }}
Global default uses USD; replace it with your bill's all-in kWh price.
$ /kWh
Include equipment, labor, controls, permits, and required electrical work for the bid scope.
$
Subtracted from installed cost before simple payback is calculated.
$
Used only with the cooling reduction field below.
kWh/yr
Positive values add cooling-side savings to the annual result.
%
Default is zero and does not change the base operating result.
$ /yr
Subtracts from annual savings when backup heating is expected.
$ /yr
Choose a short horizon for a near-term move or a longer horizon for permanent equipment.
years
Metric Value Calculation note Copy
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Check Status Bid note Copy
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Tags: Energy, Home Improvement, Home Systems, Household
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Heat pump savings are not measured by comparing the nameplate efficiency of two appliances. The useful comparison starts with the heat a home actually receives from its current system, then asks how much electricity a heat pump would need to deliver the same heat across a season. Fuel units, system efficiency, delivered fuel price, electricity price, backup heat, and climate performance all shape the answer.

A furnace, boiler, or electric-resistance system converts purchased energy into indoor heat. Combustion systems lose part of the fuel heat through flue gases, cycling, and distribution losses. Electric resistance turns electricity into heat at about a one-to-one energy ratio. A heat pump is different because it moves heat rather than generating all of it directly, so one unit of electricity can deliver multiple units of heat when conditions are favorable.

Fuel use converted to delivered heat and then compared with heat pump electricity at seasonal COP.

Coefficient of performance, or COP, is a seasonal estimate of useful heat delivered per unit of electricity consumed. HSPF2 is a rated seasonal heating efficiency in Btu per watt-hour. Both can be used for planning, but neither guarantees the exact bill change in a specific home. Duct leakage, thermostat settings, backup heat, defrost cycles, envelope quality, and weather normalization can change the realized savings.

Simple payback is only one financial view. It ignores financing, fuel escalation, maintenance surprises, comfort improvements, equipment life, tax liability, and resale value. It is most useful as an early comparison between the current heating bill and a quoted heat-pump project cost.

How to Use This Tool:

Use a real heating season when possible. Presets are only starting points for common retrofit cases.

  1. Choose an Upgrade preset, then confirm Current heating fuel. The fuel choice sets the unit, default heat content, default price, and efficiency starting point.
  2. Enter Annual fuel use and Current system efficiency. Use heating-only fuel where possible; remove cooking, water heating, or non-heating use from the annual total.
  3. Enter the delivered Current fuel price. Use the all-in delivered price for oil or propane and the bill-based price for gas or electric resistance.
  4. Select Heat pump efficiency basis. Use Seasonal COP for a seasonal study value or contractor-modeled value. Use HSPF2 rating when the rating label is the value you have.
  5. Enter Electricity price, Installed project cost, and Confirmed incentives. Incentives are subtracted only as the dollar amount you enter.
  6. Open Advanced when cooling savings, maintenance savings, backup heat cost, or a planning horizon should affect the result.
  7. If a validation alert appears, fix the named item before reading Savings Ledger. Annual fuel use, current efficiency, heat-pump efficiency, electricity price, installed cost, incentives, and planning horizon all have bounds.

Interpreting Results:

Total annual savings is the main operating result. It combines heating operating savings with optional cooling and maintenance offsets, then subtracts backup heat cost. If the summary says annual cost is added, the entered electricity price and seasonal efficiency do not beat the current fuel case.

Simple payback divides Net install cost by positive annual savings. A short payback does not prove the project is the best HVAC choice, and a slow payback does not capture comfort, carbon, cooling, or reliability reasons for switching.

Use Break-even Check to verify the economics. The Break-even electricity price shows the highest kWh price that would match current delivered heat cost. The Break-even heat pump efficiency shows the COP needed at the entered electricity price.

Technical Details:

The model converts current fuel use to delivered heat before comparing operating costs. For combustion fuels, heat content is multiplied by current system efficiency. For electric resistance, purchased kWh is converted to Btu and treated as 100% delivered efficiency unless the user changes the efficiency value.

Heat pump electricity is calculated from the same delivered heat requirement and the selected seasonal COP. When HSPF2 is selected, it is converted to an approximate COP by multiplying by 0.293071, because HSPF2 is expressed as Btu per watt-hour and COP is useful heat divided by electrical input in matching energy units.

Formula Core:

The main equations compare delivered heat cost, annual operating savings, and net install cost.

delivered heat = fuel use×Btu per unit×current efficiency heat pump kWh = delivered heat3412.142×COP annual savings = current heating cost-heat pump heating cost+cooling savings+maintenance savings-backup heat cost simple payback = installed cost minus incentivesannual savings
Quantity Rule used Interpretation effect
Fuel heat content Natural gas 100,000 Btu/therm, propane 91,500 Btu/gal, heating oil 138,500 Btu/gal, electricity 3,412.142 Btu/kWh. Sets the delivered heat base before price comparison.
HSPF2 conversion Seasonal COP equals HSPF2 multiplied by 0.293071. Allows rating-label input to feed the same kWh calculation.
Net install cost Installed project cost minus confirmed incentives, floored at zero. Used for simple payback and lifetime net savings.
Payback status Cost increase, strong payback up to 7 years, moderate up to 12 years, slow above that. Frames the planning result; it is not a financing or tax decision.

Example substitution: 12,000 kWh of electric resistance heat at $0.16/kWh costs $1,920. A heat pump with 3.2 COP needs about 3,750 kWh to deliver the same heat, costing $600 at the same electricity price. The heating operating savings are about $1,320 per year before optional cooling, maintenance, backup heat, installed cost, and incentives are considered.

Accuracy Notes:

This is an economic model, not an HVAC design. Real savings can change if the home needs weatherization, duct repair, different thermostat settings, backup heat, or a cold-climate performance review.

  • Use a full heating season or weather-normalized annual use when comparing fuel bills.
  • Use marginal electricity price, including delivery charges that rise with kWh use.
  • Enter only confirmed incentives for the equipment, location, install date, and tax situation.
  • Ask the contractor for cold-weather capacity and backup-heat assumptions when winter design temperature matters.

Worked Examples:

Electric baseboard replacement. The default case uses 12,000 kWh per year of electric resistance heat, 100% current efficiency, 3.2 COP, $0.16/kWh electricity, $9,000 installed cost, and $1,500 confirmed incentives. Savings Ledger shows a positive Total annual savings because the heat pump uses far fewer kWh for the same delivered heat.

Propane in a cold climate. A propane system with high delivered fuel price can show strong operating savings, but a conservative seasonal COP and backup heat cost may lengthen Simple payback. Break-even heat pump efficiency helps decide whether a quoted cold-climate unit is likely to beat the propane case.

Validation fix. If Heat pump seasonal COP is set to zero, the tool reports that the value must be greater than zero. Enter a positive seasonal COP or switch to HSPF2 rating with a valid rating before reading the payback result.

FAQ:

Should I use COP or HSPF2?

Use Seasonal COP when you have a modeled seasonal value. Use HSPF2 rating when the product rating is the value available.

Why can savings be negative?

Negative savings means the modeled heat-pump heating cost plus selected adjustments is higher than the current heating cost under the entered rates and efficiency.

Does simple payback include financing?

No. Simple payback divides Net install cost by annual savings. It does not include loan interest, energy inflation, equipment life, or tax liability.

Why are incentives entered manually?

Eligibility can depend on equipment, location, tax year, utility program, installer rules, and install date. The calculator subtracts only the Confirmed incentives amount you enter.

Glossary:

COP
Coefficient of performance, or useful heat delivered divided by electricity consumed.
HSPF2
A seasonal heating efficiency rating expressed as heating output in Btu per watt-hour.
MMBtu
One million Btu, used here to compare delivered heat costs across fuels.
Simple payback
Net install cost divided by annual savings when annual savings are positive.

References: