Home Heating CO2 Emissions Calculator by Energy Source
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/10/2026
Heating emissions are calculated with annual need (kWh) × the energy source's emission factor. For 12,000 kWh, natural gas heating emits about 2.7 tonnes of CO2 per year, versus 3.9 tonnes for oil and about 0.14 tonnes with a heat pump.
Explanation
For an identical heating need, the energy source used changes CO2 emissions by a factor of more than 25 between the extremes. This calculator applies to a common annual energy need (expressed in kWh of useful heat) the emission factor of each energy, on a life-cycle basis: domestic heating oil emits about 324 g of CO2 equivalent per kWh, LPG 272 g, natural gas 227 g, while wood — logs and pellets alike — drops to around 30 g, the carbon released in combustion being considered reabsorbed by the growth of a sustainably managed forest. Electricity via convector heaters is valued here at 40 g per kWh, the French average mix value on a life-cycle basis already used by our French electricity CO2 emissions calculator: this value is very low thanks to nuclear and hydro, but ADEME uses a noticeably higher factor for electric heating specifically, because its demand concentrates during cold snaps, when peak gas plants run. A heat pump, finally, delivers 3 to 4 kWh of heat for 1 kWh of electricity consumed (its coefficient of performance, or COP): its emissions are therefore those of electricity divided by that COP, making it by far the lowest-emission solution from the French grid. This calculator covers emissions; lowering the heating need itself — for example by turning the thermostat down, as our heating savings from a lower temperature calculator quantifies — cuts emissions proportionally whatever the energy source.
Example: 12,000 kWh of need, natural gas heating
Inputs
Annual heating need: 12,000 kWh. Energy: natural gas (227 g CO2e/kWh).
Calculation
Emissions = 12,000 × 227 ÷ 1000 = 2724 kg of CO2 equivalent, about 2.7 tonnes per year.
Result
This gas heating emits about 2.7 tonnes of CO2 equivalent per year.
Frequently asked questions
Why is wood counted at only 30 g of CO2 per kWh when it releases CO2 when burned?
Burning wood does release CO2, but this CO2 was captured by the tree during its growth and will be recaptured by the regrowing forest, provided it's sustainably managed (as much wood regrowing as harvested). The 30 g counted correspond to residual emissions: forestry machinery, drying, transport, and pellet manufacturing. This reasoning assumes a local, sustainable wood supply chain, which isn't guaranteed for all sourcing.
Why does heating electricity sometimes have a factor much higher than 40 g?
40 g per kWh is the annual average of the French electricity mix. But electric heating doesn't consume uniformly all year: it consumes mostly during winter cold snaps, precisely when France calls on its peak gas plants and imports more carbon-intensive electricity. ADEME therefore uses a "seasonalized" factor several times higher for electric heating. This calculator shows the annual average value to stay consistent with the rest of the site, but a convector heater's actual impact is probably higher.
How do I estimate my annual heating need in kWh?
For gas or oil heating, consumption appears on your bills (in kWh for gas, to be converted from liters for oil, about 10 kWh per liter). For electric heating, isolate the heating share of your total consumption (by comparing a winter month to a summer month). As an order of magnitude, an unrenovated 1980s house often consumes 15,000 to 20,000 kWh of heating per year, versus 5,000 to 9,000 kWh after a high-performance energy renovation.