Heat pump operating costs depend on the heat delivered, electricity rate, existing fuel price, system efficiency, climate, and how the equipment is sized and controlled. A useful estimate starts with your actual heating bill and shows its assumptions instead of promising one national savings number.
Start with the bill, not the equipment price
Separate the project into three questions:
- What do you spend on heating now?
- What electricity use would deliver a similar amount of heat?
- How does the installation cost change after verified incentives?
The Zam Green calculator uses your monthly heating cost, current heating fuel, ZIP code, and a planning electricity rate. Its result is an operating-cost scenario. It is not an installer quote, a utility approval, or a promise of future energy prices.
The inputs that move the result
Electricity rate
The same heat pump can cost more or less to run at different electricity rates. Use the rate on your bill when you have it. A ZIP-based rate is a planning starting point, not a tariff quote. Time-of-use rates, demand charges, riders, and seasonal prices can change the result.
Current fuel and heating cost
Gas, oil, and electric resistance heat have different units and efficiencies. A monthly bill also includes weather, thermostat settings, hot water, and non-heating loads unless you isolate the heating portion. Use a winter average or a utility usage history when possible.
Heat pump performance
COP describes how much heat a system delivers relative to the electricity it uses at a particular operating point. Seasonal performance depends on outdoor temperature, defrost cycles, backup heat, duct losses, sizing, and controls. A nameplate rating is not the same as a whole-home seasonal result.
Installation cost and incentives
An incentive reduces project cost only when the program is open and the project qualifies. The verified utility directory keeps program claims separate from the calculator. A provider amount such as "up to" is a ceiling, not an automatic subtraction.
A simple comparison method
Use the following worksheet:
| Input | What to use |
|---|---|
| Current monthly heating cost | A representative bill or heating-only estimate |
| Current heating source | Gas, oil, or electric resistance |
| Electricity rate | Your bill rate, then a seasonal or time-of-use check |
| Heat pump system | Proposed capacity, efficiency, and backup-heat plan |
| Installed price | An itemized quote, including electrical or duct work |
| Verified incentives | Only amounts confirmed by the provider for this project |
Then compare annual operating cost, net installed cost, and the payback period. Do not compare an optimistic savings scenario with a fully loaded installation quote or compare a guaranteed invoice discount with an unverified rebate maximum.
What the calculator does not include automatically
The tool does not know your contractor's final price, exact equipment performance, building heat loss, maintenance, financing, demand charges, or future fuel prices. It also does not know whether a program will approve the application. Replace the planning assumptions with your bills, load calculation, quote, and provider terms before signing a contract.
For a cold-climate project, ask about low-temperature capacity and backup heat. For a warm-climate project, cooling efficiency and system sizing may matter as much as winter heating. A Manual J load calculation can help prevent oversizing; OPPD specifically encourages a Manual J or equivalent calculation for HVAC projects.
Operating savings versus total project savings
Operating savings are the recurring energy-cost difference. Total project savings may also include a verified rebate, an installer discount, maintenance changes, and financing costs. Keep those values separate so a rebate does not hide a high-interest loan or a large electrical upgrade.
The 2026 rebate guide explains which administrator controls each incentive. The eligibility guide explains why an equipment rating alone is not enough.
A better decision rule
Use a range instead of one precise forecast. Run a conservative, expected, and high-savings case by changing the electricity rate, heating cost, installation price, and verified incentive. If the project only works in the high case, ask for better measurements or a lower installed price before moving forward.
The calculator is most useful when it helps you identify the next question: which bill should be used, what model was quoted, whether backup heat is included, or which provider rule must be confirmed. That is more reliable than treating a single annual number as a guarantee.