Heat Pump vs Gas Furnace in Hawaii: 2026 Running Costs
Hawaii records about 0 heating degree days a year, so there is effectively no heating season and almost nothing to save either way. The real question here is cooling, not heating.
Heat pump vs gas furnace — Hawaii
Running cost for heating. Adjust anything to see the gap move.
Gas furnace is cheaper to run by
$0
per year · the heat pump never recovers its extra cost here
Heat pump / year
$0
0 kWh · COP 3.60
Gas furnace / year
$0
0 therms
Seasonal efficiency is modelled at COP 3.60 for this climate. Calculators that assume a flat COP of 3 everywhere overstate cold-climate performance — and that is where surprise winter bills come from.
The numbers behind it
| Heating degree days | 0 |
|---|---|
| Electricity rate | 44.61¢ / kWh |
| Natural gas price | $5.05 / therm |
| Modelled home size | 2,000 sq ft |
| Annual heat needed | 0.0 million BTU |
| Seasonal COP (modelled) | 3.60 |
| Heat pump electricity | 0 kWh |
| Gas used | 0 therms |
| Heat pump running cost | $0 |
| Gas furnace running cost | $0 |
| Annual difference | $0 for gas |
| Break-even gas price | $0.00 / therm |
| Break-even power price | 0.0¢ / kWh |
| Payback on install premium | Never on running cost |
Why the honest answer is often “it depends”
A heat pump wins where electricity is cheap relative to gas and the winter is mild enough to keep seasonal efficiency high. It loses where gas is cheap, power is expensive, or the climate is cold enough to drag efficiency down and call on resistance backup. In Hawaii the balance currently falls in the gas furnace's favour on running cost — but rebates, a dying air conditioner, or a gas price move can each flip that.
Common questions
Is a heat pump cheaper than gas heating in Hawaii?
Hawaii has essentially no heating season, so the question is close to moot. A heat pump is still usually the sensible choice because it provides the cooling you actually need.
Do heat pumps work in Hawaii's climate?
They work, but efficiency falls with temperature. At 0 heating degree days we model a seasonal COP of 3.60 — roughly 3.6 units of heat per unit of electricity across the season, not the 3+ that mild-climate marketing implies.
How long does a heat pump take to pay for itself in Hawaii?
It doesn't, on running cost alone — it costs more to run here, so the extra install cost never comes back through the energy bill. The case rests on rebates, replacing a dying air conditioner at the same time, or reasons other than money.
What electricity price would make a heat pump worthwhile in Hawaii?
Below about 0.0¢ per kWh, holding gas at $5.05 a therm. Hawaii averages 44.61¢, which is above that line. Equivalently, gas would need to reach $0.00 a therm for the two to level at today's power price.
Does this include air conditioning?
No, and that matters. A heat pump is also an air conditioner, so if you were replacing a failing AC anyway, the true extra cost is much lower than the figure used here — sometimes near zero. This compares heating running costs only.
How we calculate this
Annual heat demand comes from heating degree days and a modelled building heat-loss rate, then met two ways: a gas furnace at 92% efficiency, and a heat pump at a seasonal COP derived from the local climate.
That climate-varying COP is the part most calculators skip. Applying one flat efficiency everywhere assumes a mild winter in a cold state, and is the single biggest reason published heat pump savings often fail to appear on real bills.
Excluded: cooling benefit, rebates and incentives, maintenance differences, and any electrical panel upgrade. Analysis horizon 15 years.
Data vintage: Electricity: EIA Electric Power Monthly Table 5.6.B (residential, May 2026 YTD). Solar resource: PVGIS v5.3 (EU JRC), ERA5 2005-2023. Gasoline: AAA state averages. Natural gas: EIA residential by state. Heating degree days: NOAA CPC population-weighted normals. Retrieved 2026-08-03/04. Install costs, household usage, net-metering status, annual mileage, time-of-use spreads and outage hours remain estimates.