How do I convert therms or cubic metres of gas to kWh?

One therm is about 29.3 kWh. One cubic metre of natural gas is about 10.6 to 11.2 kWh depending on calorific value. This tool lets you enter gas directly in kWh or therms and converts therms for you, so use whichever your bill shows.

What emission factors are used?

Natural gas is about 0.183 kgCO2e per kWh and heating oil about 2.52 kgCO2e per litre. Electricity uses your selected grid factor, since it varies hugely by country, from under 50 gCO2/kWh on very clean grids to over 600 on coal-heavy grids.

Why is electricity's footprint so variable?

Gas and oil burn the same wherever you are, so their factors are fixed. Electricity's carbon depends entirely on how it was generated, which differs by country and even by time of day. That is why the grid factor is a separate, adjustable input here.

What reduction action saves the most?

For most homes, cutting gas heating demand through insulation, draught-proofing, and a lower thermostat saves the most, because gas is usually the largest single energy use. Switching to a heat pump on a clean grid and to a renewable electricity tariff are the next biggest levers.

Does this include embodied or food emissions?

No. This calculator covers operational energy only: gas, electricity, and heating oil consumed in the home. Food, travel, goods, and the embodied carbon of the building itself are separate categories not included in this figure.

Home Energy CO2 Calculator

Household energy is typically the second-largest part of a personal carbon footprint after travel, and most of it hides in heating. This calculator combines your gas, electricity, and heating-oil use with the right emission factors to give a single annual CO2e figure, then ranks the actions that would cut it the most.

How it works

gas CO2e   = gas_kWh × 0.183
elec CO2e  = elec_kWh × (grid gCO2/kWh ÷ 1000)
oil CO2e   = oil_litres × 2.52
total      = gas + elec + oil   (kg CO2e per year)

Gas and oil factors are fixed because the fuel burns identically everywhere; electricity uses the grid factor you choose, which is the single biggest swing in the result.

Reduction actions ranked

The tool estimates savings from common measures and orders them by impact:

Lower the thermostat 1°C — roughly 8 percent of heating demand.
Switch to a renewable electricity tariff — removes most of the electricity CO2e.
Insulation and draught-proofing — commonly 10 to 20 percent of heating.

Notes

Enter gas in kWh or therms (1 therm ≈ 29.3 kWh) and heating oil in litres. The figure covers operational home energy only — not food, goods, or travel — so combine it with the commute and flight calculators for a fuller picture.