What are the UK emission factors for different fuels?

The UK Government publishes official emission factors annually. Key values: mains gas 0.21 kg CO₂/kWh, heating oil 0.27, grid electricity 0.23 (falling each year as renewables increase), LPG 0.24, coal 0.34, wood pellets 0.04 (near carbon-neutral). Heat pumps use electricity at COP 3.0, giving an effective rate of 0.077 kg CO₂/kWh of heat delivered.

How much CO₂ does the average UK home produce?

The average UK home emits approximately 2.7 tonnes of CO₂ per year from heating (based on typical gas consumption of 13,000 kWh). Including electricity for other uses, the total is about 4.5 tonnes per home. The UK government aims to reduce this significantly through insulation improvements, heat pump adoption, and grid decarbonisation by 2035.

How much CO₂ does a tree absorb per year?

A mature UK broadleaf tree absorbs approximately 22 kg of CO₂ per year. A young, fast-growing tree may absorb less as it establishes. To offset an average gas-heated home (2.7 tonnes CO₂), you would need approximately 123 trees. This is a simplification — the actual absorption depends on species, age, health, and growing conditions.

Is electricity greener than gas for heating?

Electricity from the grid (0.23 kg CO₂/kWh) produces slightly more CO₂ per kWh than gas (0.21). However, heat pumps deliver 2.5-4 kWh of heat per 1 kWh of electricity, making them 60-75% lower carbon than gas boilers. As the UK grid decarbonises (target: zero carbon by 2035), heat pumps will become increasingly greener. Direct electric heating is currently similar to gas in carbon terms.

How can I reduce my home's carbon emissions?

The most effective measures in order: (1) Insulate — reducing heat demand is always the first step. (2) Install a heat pump — replaces gas/oil with efficient electric heating. (3) Switch to a green electricity tariff. (4) Install solar PV. (5) Draught-proof. (6) Use smart heating controls. A well-insulated home with a heat pump and solar PV can reduce emissions by 80-90%.

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Carbon Emission Calculator — Home Heating CO₂

Calculate annual CO₂ emissions from home heating by fuel type. Compare against UK averages and see how many trees would offset your emissions.

Fuel Type

Your primary heating fuel

Annual Consumption

From your energy bills

Household Size

For per-capita calculation

How We Calculate This

This calculator converts your annual fuel consumption into CO₂ emissions using UK Government emission factors, then compares the result to national averages.

The formula

Annual CO₂ (kg) = Annual consumption (kWh) × Emission factor (kg CO₂/kWh)

Annual CO₂ (tonnes) = kg ÷ 1000

Trees to offset = CO₂ (kg) ÷ 22 kg per tree per year

For example, a gas-heated home using 15,000 kWh/year: 15,000 × 0.21 = 3,150 kg = 3.15 tonnes CO₂/year. Trees to offset: 3,150 ÷ 22 = 144 trees.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.