Free check · 2 minutes · San Francisco Peninsula
Gas or heat pump: which one costs less every month?
Tell us about your house. We’ll show what you pay PG&E now and what you’d pay with a heat pump — a machine that heats in winter and cools in summer using electricity instead of gas.
- Houses like yours. Thousands of Peninsula homes were modeled by a U.S. energy lab. We take the ones like yours.
- Today’s PG&E prices. The real price of a kilowatt-hour and a therm, hour by hour.
- Your solar counts. Have panels or a battery? Add them and see how much of the heat pump runs on your own sun.
- No tricks. You get a range, not one magic number. If something gets more expensive, we say so.
How a heat pump works, in one picture
Gas furnace
1 therm of gas → 0.8–0.96 therm of heat
It burns gas. Some heat always goes up the vent pipe.
Heat pump
1 unit of electricity → 3–4 units of heat
It moves heat from the outside air into the house.
- A furnace makes heat by burning gas.
- A heat pump moves heat instead — like a fridge, but in reverse.
- That’s why it gives back 3–4 times more heat than the electricity it uses.
- In summer it runs backwards and cools the house.
Your bills, now and with a heat pump
See what a heat pump really costs you over 10 years
Price with the rebate, the $0-upfront 0% loan, and your 10 years of lower bills — in one number.
Good to know
- Where the numbers come from. A U.S. government energy lab (NREL) built computer models of thousands of real California homes. We pick the homes that look like yours and show the middle one and the typical range.
- Real PG&E prices. The price of electricity depends on your plan and the hour. On most plans it’s highest from 4 to 9 pm; on the electric-car plan (EV2-A) it’s high from 3 pm to midnight and cheapest overnight. Gas costs more in winter once you use a lot. We use your plan’s own hours, month by month.
- The secret rate plan. Own a heat pump and PG&E lets you pick a plan called E-ELEC. It makes winter electricity cheaper for the whole house, not just the heat pump. We tell you when to switch.
- A guess, not a bill. Your thermostat, your windows and your family change the result. Type in your own kWh and therms above and the model fits your house.
How we calculate
- Homes. NREL ResStock 2025 — the U.S. Department of Energy’s computer models of real housing. We use the San Mateo, San Francisco and Santa Clara County homes and group them by climate zone, home type, heating, air conditioning, year built and size. You see the middle of the group and the range where most homes land.
- Equipment. Today’s system as you describe it. Heat pump: a typical ducted cold-climate model (SEER2 17.5, HSPF2 8.5); for homes without ducts, a ductless mini-split. Heat pump water heater: NREL’s heat pump water heater model; a standard electric tank for comparison (0.92 efficiency). Furnace upgrade: an 80% furnace replaced with a 95% one. Dual fuel: the heat pump plus your furnace, which takes over 4–9 pm.
- Weather. Hour-by-hour temperature and sunshine for your county.
- Prices. PG&E tariff sheets: electric E-TOU-C, E-ELEC, EV2-A and E-1 with baseline allowances (June 2026), gas G-1 with baseline tiers (October 2026), the monthly base charge, and the Solar Billing Plan export credit. With a heat pump we pick the cheaper of E-ELEC and E-TOU-C for you.
- Solar and battery. Your system size or monthly numbers, spread over the day by your county’s sunshine. The battery charges from extra sun and runs the house in the evening and at night.
- Your bills. If you enter your yearly kWh and therms, the model is scaled to your house.
- CO₂. From the same NREL models: gas burned at home plus the average emissions of California electricity.
- Not included. Your thermostat habits, drafts, future price changes (unless you tick the 5% box), and repairs. This is an estimate, not a bill.
Questions people ask
Will a heat pump cost more to run than my gas furnace?
For most Peninsula homes, no. A furnace turns one dollar of gas into about 80 cents of heat. A heat pump turns one dollar of electricity into three or four dollars’ worth of heat. On the E-ELEC plan that beats gas at today’s prices. On the regular E-TOU-C plan the two are close — so the calculator tells you which plan to pick.
I have solar panels. Does that change things?
Yes, but not the way most people think. Heating happens at night and early in the morning, when panels make almost nothing. So for heating, a battery helps more than the panels. Cooling happens in the afternoon sun — so the heat pump’s air conditioning runs almost for free. Enter your system above to see your own numbers.
Can I keep my furnace as a backup?
You can — that’s called dual fuel. But you give up almost everything that makes a heat pump pay off: no $1,500 WestLight rebate, no 0% loan, and no cheaper E-ELEC rate plan. On the Peninsula it rarely gets cold enough for the furnace to beat the heat pump, so keeping it saves you almost nothing on bills. It makes sense in one case: you have solar panels and mainly want the heat pump for cooling on sunny afternoons, while the furnace keeps doing the heating.
What about CO₂?
Burning gas at home makes CO₂. A heat pump makes about half as much today, because much of California’s electricity comes from the sun, wind and water, and it gets cleaner every year.
What does “air conditioning you gain” mean?
If your house has no AC today, a heat pump gives you cooling you never had. Running it costs money, and we show that cost as its own line instead of hiding it inside the total. Think of it as the price of a cool house in September.