On running cost alone, a natural gas furnace beats a heat pump in Maine: $24.91 per million Btu of heat delivered, against $37.02 for a heat pump at the ENERGY STAR minimum. That $12.11 gap comes from average residential prices published by the U.S. Energy Information Administration (EIA). Most Maine homes do not list gas as their main fuel, though, and for them the real contest is a heat pump against electric baseboard.
The short answer for Maine
Here is the full ranking, computed from EIA average residential prices for electricity and natural gas and from ENERGY STAR efficiency figures. Per million Btu of heat delivered into the house: a natural gas furnace at 97% AFUE costs $24.91, a heat pump at 8.1 HSPF2 costs $37.02, and electric baseboard at 100% efficiency costs $87.90. The furnace is the cheapest to run here, $12.11 less per million Btu than the heat pump. The heat pump sits far below baseboard, which is the comparison that matters in a house with no gas service.
Read these numbers for what they are. They show running cost on the same unit of heat, not a yearly bill. A yearly bill depends on square footage, insulation, air leaks and where you set the thermostat. They are also not the price of equipment. Buying and installing a furnace, a ducted heat pump or a ductless system is a separate cost, and it can reverse the verdict over a system’s lifetime.
The gap exists because electricity in Maine is expensive, averaging 29.99 cents per kWh by EIA’s count. A heat pump has to squeeze a seasonal coefficient of performance of about 2.4 out of every kilowatt-hour just to land within reach of gas. A 97% AFUE furnace, meanwhile, turns nearly all of its fuel into heat, and gas is cheap per Btu. If gas already runs to your house, the furnace wins on running cost; if it does not, the heat pump is the far cheaper electric option.
What each option costs to run in Maine
The table below copies the computed figures. Each row shows the efficiency assumed and the cost of one million Btu of heat delivered to the house.
| System | Efficiency used | Cost per million Btu delivered |
|---|---|---|
| Electric baseboard | 100% efficient | $87.90 |
| Heat pump | 8.1 HSPF2 (seasonal COP about 2.4) | $37.02 |
| Natural gas furnace | 97% AFUE | $24.91 |
Two prices sit behind those rows. The electricity figure is 29.99 cents per kWh, the average residential price year-to-date through July in the EIA’s Electric Power Monthly, Table 5.6.B. It is a statewide average, so your utility and rate plan may differ. The gas side uses EIA’s average residential natural gas price, converted at about 1,037 Btu per cubic foot, with electricity converted at 3,412 Btu per kWh. Gas rates vary by utility, so the local utility is the place to get your actual price per therm or per hundred cubic feet.
Efficiency moves the result as much as the fuel price does. A kilowatt-hour run through baseboard produces exactly 3,412 Btu of heat, and nothing more. The same kilowatt-hour run through a heat pump at a seasonal COP of about 2.4 moves roughly 2.4 times that into the house, which is why $87.90 shrinks to $37.02 without any change in the electric rate. The furnace plays the opposite game: its fuel is cheap per Btu, and it wastes only a few percent.
The heat pump figure uses the ENERGY STAR minimum for a ducted system, 8.1 HSPF2. For a non-ducted (ductless) system, the same label demands 8.5, because with no duct losses a ductless unit starts with an advantage and has to be better to earn the badge. These are minimums to earn the label, not typical values, so a stronger unit would do better on paper. The distinction behind the two thresholds is covered in What HSPF2 Measures, and Why Ductless Asks for More. When you compare two units, compare the same letter: HSPF2 for heating, SEER2 for cooling.
How cold it gets, and what that does to a heat pump
Portland International Jetport, the reference city here, logs about 6,795 heating degree days a year (base 65°F), per NOAA’s 1991-2020 Climate Normals. Heating degree days add up, for every day, how far the mean temperature sat below 65°F. More of them means more fuel for the same house, so a count this size describes a long heating season, not a short brutal one. The coldest month has a mean daily minimum of 15.6°F, and that is an average of the nights, not the worst of them.
Portland is one coastal station. Inland and mountain areas of the state can run far colder, so a house in a northern or high-elevation town should expect a harder winter than these numbers suggest.
Here the $37.02 figure needs a caveat. It rests on a seasonal efficiency, an average across the whole heating season. Heat pump efficiency drops in deep cold, so the coldest weeks cost more per Btu than that average implies. On the coldest nights, a backup carries part of the load, either electric resistance strips built into the unit or a separate furnace. Resistance strips deliver heat at the baseboard rate, the $87.90 row in the table. A furnace as backup, running on gas, brings the cost closer to the $24.91 row.
That is the reason the backup question matters more in Maine than in a mild climate, where a heat pump barely leaves its efficient range. How a unit holds up as temperatures fall is a matter of its design, and How Cold Is Too Cold for a Heat Pump goes through it in detail. Treat $37.02 as a seasonal average and expect the coldest weeks to cost more than that.
What homes in Maine already heat with
The EIA’s 2020 Residential Energy Consumption Survey (RECS) gives state shares for equipment and for fuel, in two separate tables, so the percentages do not add up to one list. By equipment, 46% of Maine homes use a furnace and 31% use a steam or hot-water boiler. For central heat pumps the survey does not publish a figure: the estimate was suppressed as unreliable, which is not the same as zero.
By main fuel, fuel oil or kerosene leads at 49%. Natural gas follows at 17%, propane at 16% and electricity at 10%. These shares describe what was installed over the decades, which is to say which fuel looked cheap when each house was built. They are statewide numbers from a national survey, not a count for your county, and they are not a recommendation.
What they do tell you is that gas is the exception here. A house without a gas line cannot choose the $24.91 option, so the useful comparison is a heat pump against whatever it burns now, and this page carries no price for oil or propane to rank them. A boiler house is a different conversion again. Hot-water radiators mean no ducts, so a ducted heat pump would require adding them, while a ductless system skips that work. The trade-offs are laid out in Ductless or Central, and the broader view of how Maine households heat is in Heating a Home in Maine. Before pricing anything, find out whether you have a gas line, ductwork or a boiler loop.
When the other choice wins
The cheaper-to-run furnace is not always the right call. Start with the obvious one: no gas service. If the street has no main, or the utility will not extend one to your lot, the $24.91 figure is irrelevant, and the choice is between a heat pump at $37.02 and baseboard at $87.90.
Cooling also tilts the scale. Portland averages about 447 cooling degree days a year, a modest cooling season, but one that a gas furnace does nothing about. A heat pump heats and cools with the same equipment, and ENERGY STAR sets the cooling floor at 15.2 SEER2 for the label. If you would otherwise buy a furnace and a separate air conditioner, the running-cost gap shrinks once you count both.
A dual-fuel setup splits the difference. The heat pump handles the milder stretches, and the furnace carries the coldest nights, which is where heat pump efficiency falls off. That keeps the furnace’s low running cost in play when it matters most, and it avoids leaning on resistance strips. It does mean owning and maintaining two systems.
Age matters too. A furnace with years of service left has already been paid for, and replacing it to save on running cost means a large outlay against modest annual savings. The decision between fixing and swapping is covered in Repairing a Furnace or Replacing It. A furnace with years left is usually worth keeping while you price its replacement.
Common questions
Is a heat pump cheaper to run than a gas furnace in Maine?
No. Using EIA average residential prices, a heat pump at 8.1 HSPF2 costs $37.02 per million Btu delivered and a 97% AFUE gas furnace costs $24.91. The heat pump is far cheaper than electric baseboard, at $87.90.
Does the $37.02 figure hold on the coldest nights?
Not exactly. It uses a seasonal average efficiency, and a heat pump’s efficiency drops in deep cold. On the coldest nights a backup, either resistance strips or a furnace, supplies part of the heat.
Do I have to keep my furnace if I add a heat pump?
No, but it is one way to cover the coldest nights. Keeping the furnace gives you a dual-fuel setup, with the heat pump doing most of the work. Skipping it means relying on the unit’s built-in resistance strips or on its low-temperature performance.
Is the cost per million Btu my yearly heating bill?
No. It compares fuels on the same unit of delivered heat. Your bill depends on the size and insulation of the house, how you use it, and your local utility rates.