Phase 3 · Sustainable Transitions
Heat Pump Savings Calculator
Swapping a gas furnace for a heat pump can shrink your heating bill — or quietly raise it. The answer is all in your local energy prices and efficiency. Run yours before you commit.
Under the hood
The math, fully exposed
Both systems deliver the same heat; we price the energy each one burns to do it (1 therm = 29.3 kWh of heat):
Gas used = heat demand ÷ AFUE
Gas cost = gas used × gas price
Heat pump electricity = (heat demand × 29.3) ÷ COP
Heat pump cost = electricity × electricity rate
Annual savings = gas cost − heat pump cost
Payback = install premium ÷ annual savings
- COP is the whole story: at COP 3 the heat pump uses a third of the energy to deliver the same heat — but a cold-climate average COP can be lower, so model conservatively.
- It's a price race, not just efficiency: the result swings on the ratio of your electricity price to your gas price. Cheap gas can keep a furnace ahead even against an efficient heat pump.
- Carbon isn't priced here: a heat pump on a clean grid cuts emissions even when the dollar savings are slim — a real benefit this cost-only model doesn't capture.
Your directives
What to do next, based on your numbers
Adjust the sliders to generate tailored recommendations.
Answers
Frequently asked questions
Is a heat pump actually cheaper to run than a gas furnace?
It depends on three things: your electricity price, your gas price, and the heat pump's efficiency (COP). Because a heat pump moves heat rather than burning fuel, it delivers 2.5–4 units of heat per unit of electricity. Where electricity is reasonably priced and gas is expensive, it usually wins — but with cheap gas and pricey power, a furnace can still cost less to run.
What is COP and how can it be over 100% efficient?
COP (Coefficient of Performance) is heat delivered ÷ electricity consumed. A COP of 3 means 3 kWh of heat for every 1 kWh of power — "300% efficient." That's not breaking physics: the heat pump isn't creating energy, it's pumping existing heat from outside air into your home, which takes far less energy than generating heat by combustion.
Do heat pumps work in cold climates?
Modern cold-climate heat pumps work well below freezing, but efficiency (COP) drops as it gets colder, so your real-world average COP is lower than the rating. In very cold regions many homes use a heat pump for most of the season with gas or electric-resistance backup for the coldest days. Lower the COP slider to model a colder climate.
What about the install cost and rebates?
A heat pump often costs more to install than a like-for-like furnace, which is the premium this calculator pays back through running savings. Federal, state and utility rebates can cut that premium substantially — reduce the install-premium slider by any incentives you qualify for to see how much faster it pays off.