Carbon Emission Calculator — Home Heating CO₂

The UK Government (DESNZ) publishes official conversion factors each year. Current values (DESNZ 2026, kg CO₂e per kWh): mains gas 0.18231, heating oil (kerosene) 0.245, grid electricity 0.131 (falling each year as the grid decarbonises), LPG 0.219, house coal 0.387, wood pellets 0.012 for the combustion (CH₄ + N₂O) portion — the biogenic CO₂ from burning the wood is reported separately under the GHG Protocol rather than added to your scope-1 total, which is why pellets are often described as near carbon-neutral. Heat pumps use grid electricity at a seasonal performance factor (SCOP) of about 3.0, giving an effective rate of about 0.044 kg CO₂/kWh of heat delivered (0.131 ÷ 3.0).

A typical UK gas-heated home uses about 13,000 kWh of gas a year, which at the DESNZ 2026 gas factor (0.18231 kg CO₂/kWh) is about 2.37 tonnes of CO₂ from heating. Including electricity and hot water the whole-home total is roughly 4 tonnes. Ofgem's medium Typical Domestic Consumption Value is lower again — 11,500 kWh of gas (about 2.10 tonnes), falling to 9,500 kWh from July 2026. The government aims to cut household emissions through insulation, heat-pump adoption and continued grid decarbonisation.

A mature UK broadleaf tree absorbs roughly 22 kg of CO₂ per year (a rule-of-thumb figure — a young, establishing tree absorbs less). To offset a typical gas-heated home emitting about 2.37 tonnes of CO₂ you would need around 108 trees (2,370 ÷ 22). This is a simplification: actual absorption depends on species, age, health and growing conditions, and offsetting is no substitute for cutting emissions at source.

Grid electricity (0.131 kg CO₂/kWh, DESNZ 2026) now produces less CO₂ per kWh than mains gas (0.182) thanks to the growth of renewables, so even direct electric heating is lower carbon than gas per unit of energy. Heat pumps go much further: they deliver 2.5–4 kWh of heat for every 1 kWh of electricity, making them roughly 75–90% lower carbon than a gas boiler. As the grid continues to decarbonise, heat pumps become greener still.

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%.