In 2026, a gas boiler still heats the average UK home for roughly half the annual cost of an air-source heat pump, according to DESNZ’s latest cost comparison model.
Homeowners considering a heat pump often ask how it compares to a gas boiler on running costs. The Department for Energy Security and Net Zero (DESNZ) publishes an annual cost comparison model to answer this question. For 2026, the model shows a clear gap in annual running costs.
DESNZ assumes a typical 3-bed semi-detached home with a gas price of 6.5p/kWh and an electricity price of 24.5p/kWh, paired with an air-source heat pump operating at a Seasonal Coefficient of Performance (SCOP) of 3.2 (DESNZ, Heat pump vs gas boiler: annual running cost comparison, 2026 update). The annual running cost for a gas boiler is approximately £760. The annual running cost for the heat pump is approximately £1,450. This gap narrows if the home uses a high-efficiency heat pump with a SCOP of 4.0 or higher, or if the household switches to a time-of-use electricity tariff that offers cheaper off-peak rates.
Quick numbers upfront costs, running costs, and carbon savings side by side
| Metric | Gas boiler | Air-source heat pump |
|---|---|---|
| Upfront installed cost (UK average 2026) | £2,500–£4,000 | £9,000–£14,000 |
| Annual running cost (DESNZ 2026 model) | £760 | £1,450 |
| Annual CO₂ emissions (kg per year) | 2,580 kg | 960 kg |
| Lifespan (years) | 10–15 years | 15–20 years |
Costs for installed systems come from MCS installation data for 2026 (MCS, 2026). Emissions figures are based on DESNZ grid carbon factor projections for 2026 and a 12,000 kWh annual heat demand (DESNZ, UK grid carbon intensity projections, 2026). Lifespan estimates are from the Energy Saving Trust appliance database (Energy Saving Trust, 2026).
The running-cost gap depends on your heat pump’s SCOP and your electricity tariff
The Seasonal Coefficient of Performance (SCOP) is the key efficiency measure for a heat pump. A SCOP of 3.0 means the heat pump delivers 3 kWh of heat output for every 1 kWh of electricity input (Energy Saving Trust, Heat pump running costs, 2026). A heat pump with SCOP 3.0 on a standard electricity tariff costs roughly twice as much to run as a gas boiler. A heat pump with SCOP 4.0 on a time-of-use tariff can cut that gap to about 1.3 times the gas boiler cost.
Gas boiler efficiency is assumed at 90% for a modern condensing boiler, based on the DESNZ boiler efficiency database (DESNZ, 2026). Home insulation level directly affects SCOP. A poorly insulated home may drop the heat pump’s SCOP below 2.5, making running costs higher than a gas boiler. Improving insulation before installing a heat pump is essential to maintain efficiency.
Upfront cost a heat pump installation costs 3–4 times more than a gas boiler replacement in 2026
A like-for-like gas boiler replacement in 2026 costs between £2,500 and £4,000 including installation (Energy Saving Trust, Cost of heating systems, 2026). An air-source heat pump installation costs between £9,000 and £14,000, which includes the indoor unit, a hot water cylinder, and controls (MCS register, Typical installation costs 2026).
The Boiler Upgrade Scheme (BUS) offers a grant of £7,500 for heat pump installations in England and Wales (GOV.UK, Boiler Upgrade Scheme, 2026). After the grant, the net cost of a heat pump installation falls to between £1,500 and £6,500. This makes the upfront cost much closer to a gas boiler replacement, though heat pump installations still require a larger initial investment in most cases.
Compare heat pump grants and boiler replacement costs in more detail
Carbon emissions a heat pump cuts home heating CO₂ by roughly 60% compared to a gas boiler in 2026
A gas boiler produces approximately 215 g of CO₂ per kWh of heat output, based on a gas carbon factor of 185 g/kWh and boiler efficiency of 90% (DESNZ, UK grid carbon intensity projections, 2026). An air-source heat pump produces about 80 g of CO₂ per kWh of heat output, based on a grid carbon intensity of 120 g/kWh and a SCOP of 3.5 (Energy Saving Trust, Heat pump emissions comparison, 2026).
For a home with an annual heat demand of 12,000 kWh, a gas boiler emits 2,580 kg of CO₂ per year. A heat pump emits 960 kg of CO₂ per year. As the UK grid decarbonises towards a target of 50 g/kWh by 2030, heat pump emissions will fall further, widening the carbon savings gap.
The direct answer choose a heat pump if you plan to stay 10+ years and can upgrade insulation; choose a gas boiler if upfront cost is your main constraint
This decision depends on four factors: your upfront budget, your home’s insulation level, how long you plan to stay in the property, and whether you can access a time-of-use electricity tariff (DESNZ, Heat pump vs boiler: homeowner decision guide, 2026). A heat pump is better for well-insulated homes, long-term owners (10 years or more), and homeowners who want a lower carbon footprint. A gas boiler is better for a tight upfront budget, poor insulation that cannot be improved, or short-term ownership of under five years.
If you are unsure about your insulation level, consider a home energy assessment before deciding. The running cost gap between the two systems is narrower for homes with loft insulation of at least 270mm and cavity wall insulation.
Read our guide to home insulation grants and energy performance certificates
Eligibility and installer certification you must use an MCS-certified installer for the heat pump grant, and a Gas Safe registered engineer for the boiler
The Boiler Upgrade Scheme requires that the heat pump installation is carried out by an MCS-certified installer (MCS register, 2026). You can verify an installer’s certification on the MCS register website before hiring. The installer must also hold insurance that covers a 2-year warranty period for the grant.
Gas boiler installation must be completed by a Gas Safe registered engineer (Gas Safe Register, 2026). Check the engineer’s registration online before work begins. If you are replacing a gas boiler in a new location, the installer must also be FENSA-registered to comply with building regulations (FENSA, 2026).
Find out how to check an installer’s credentials and what to do if you have a dispute
Frequently Asked Questions
According to the DESNZ 2026 cost comparison model, a gas boiler costs £760 per year to run, while an air-source heat pump costs £1,450. The gap can shrink with a high-efficiency heat pump or a time-of-use tariff.
No, a heat pump is not cheaper to run than a gas boiler in 2026. DESNZ data shows the heat pump costs £1,450 per year versus £760 for a gas boiler. However, heat pumps produce 63% less CO₂ and last longer.
According to the Energy Saving Trust, a heat pump lasts 15–20 years, while a gas boiler lasts 10–15 years. This means a heat pump may need replacing less often over time.
MCS installation data for 2026 shows an air-source heat pump costs £9,000–£14,000 to install, compared to £2,500–£4,000 for a gas boiler. The Boiler Upgrade Scheme grant can reduce the heat pump cost.
The Seasonal Coefficient of Performance (SCOP) measures heat pump efficiency. A SCOP of 3.2 is typical for 2026, meaning 1 kWh of electricity produces 3.2 kWh of heat. Higher SCOP values reduce running costs.
