# Heat Pumps vs Gas Boilers: What the Efficiency Data Actually Shows in 2026 > Heat pump running costs depend heavily on efficiency, insulation and electricity-to-gas price ratios. Here is what the data actually shows, beyond the general "heat pumps are more efficient" headline. *Section: Science — By Amelia Hart (Technology Correspondent) — Published August 2, 2026 — 5 min read* Canonical URL: https://dailyjunction.org/science/heat-pumps-vs-gas-boilers-2026 Tags: heat pumps, gas boilers, home heating, energy efficiency, cop rating ## Key takeaways - Air source heat pumps typically achieve a coefficient of performance (COP) of around 2.5 to 4, meaning they produce that many units of heat per unit of electricity consumed, compared with a gas boiler's efficiency capped close to 1 - Whether a heat pump is cheaper to run than a gas boiler depends heavily on the ratio between electricity and gas unit prices, which has narrowed but not disappeared in recent years - Heat pumps generally perform best in well-insulated homes with appropriately sized radiators or underfloor heating, and less well in poorly insulated older properties without adaptation - Government grant schemes have reduced upfront installation cost, but heat pumps still typically carry a higher installation cost than a like-for-like gas boiler replacement ## Why COP is the number that actually matters The key efficiency metric for comparing heat pumps against gas boilers is the coefficient of performance (COP) — the ratio of heat output to electrical energy input. A modern, well-installed air source heat pump typically achieves a COP somewhere between 2.5 and 4, meaning it produces two-and-a-half to four units of heat for every unit of electricity it consumes. A gas boiler, by contrast, cannot exceed a thermal efficiency of 1 — even the most efficient modern condensing boilers convert gas to heat at close to but never above 100% efficiency, since they are simply burning fuel directly rather than moving existing heat energy from outside air, which is the fundamentally different physical process a heat pump uses. ## Why higher efficiency does not automatically mean lower running cost Despite this efficiency advantage, whether a heat pump actually costs less to run than a gas boiler depends critically on the relative unit price of electricity versus gas, because a heat pump's fuel is electricity while a gas boiler's fuel is, obviously, gas, and UK electricity has historically been priced at a meaningfully higher rate per unit than gas. The relevant comparison is not COP alone but COP weighted against the electricity-to-gas price ratio: if electricity costs, for example, three times as much per unit as gas, a heat pump with a COP of 3 breaks even with a 100%-efficient gas boiler on running cost, and only becomes cheaper to run if its COP exceeds that price ratio. ## The price ratio has narrowed but not closed UK electricity-to-gas unit price ratios have narrowed somewhat in recent years compared with the wider historical gap, partly through policy adjustments aimed specifically at improving the running-cost economics of heat pumps relative to gas heating, but a meaningful gap has generally persisted. This is a large part of why heat pump running cost outcomes have been genuinely mixed in real-world reporting — well-installed heat pumps in suitable homes have delivered clear running cost savings over an equivalent gas boiler, while poorly matched installations in less suitable homes have in some documented cases shown little saving or even a modest increase in running cost. ## Why the home itself matters as much as the heat pump Heat pump performance is significantly more sensitive to the condition of the building it heats than a gas boiler's performance is. Heat pumps generally operate most efficiently delivering heat at lower flow temperatures over longer periods, which suits underfloor heating or appropriately sized radiators in a well-insulated home considerably better than the higher, shorter bursts of heat a gas boiler is typically set up to deliver in an older, less insulated property. Installing a heat pump into a poorly insulated older home without addressing insulation or radiator sizing first is a well-documented cause of disappointing real-world efficiency and running cost outcomes, independent of the heat pump's own rated COP. ## What this means for the installation decision The honest, data-grounded conclusion is that a heat pump's efficiency advantage over a gas boiler is real and significant in COP terms, but translating that into an actual lower household running cost is conditional — on the current electricity-to-gas price ratio, on the home's insulation standard, and on correct heat pump sizing and installation for the specific property. Government grant schemes have meaningfully reduced the upfront capital cost gap between a heat pump and a like-for-like gas boiler replacement, but a heat pump installation still typically carries a higher upfront cost, making a proper, property-specific assessment — rather than relying on general efficiency headlines alone — the genuinely useful step before committing to either option. ## Noise, space and planning considerations that affect the real-world decision Beyond the efficiency and running cost comparison covered above, several practical installation factors genuinely affect whether a heat pump is a realistic option for a specific property, independent of the underlying efficiency numbers. Air source heat pumps require external unit placement with adequate airflow clearance, and while modern units have become considerably quieter than earlier generations, noise output remains a genuine consideration for smaller properties, terraced housing with limited garden or side-access space, or properties in conservation areas where external unit placement may require additional planning permission considerations that a straightforward like-for-like gas boiler replacement would not trigger. Ground source heat pumps, which achieve generally higher and more consistent efficiency than air source models by drawing heat from stable underground temperatures rather than variable outdoor air, require considerably more substantial installation work — either boreholes or trenched ground loops — making them a realistic option only for properties with sufficient outdoor space and appropriate ground conditions. Hot water storage is a further practical difference worth understanding: heat pumps generally work most efficiently paired with a larger hot water cylinder than many UK homes currently have installed, particularly those that have moved to a combi boiler system with no cylinder at all, meaning a heat pump installation for a combi-boiler household often requires finding space for and installing a hot water cylinder as part of the wider project, adding both cost and a genuine space requirement that needs planning for before installation. ## The installer quality question that data alone cannot fully capture Finally, it is worth being clear that a meaningful share of the disappointing real-world heat pump performance reported in some studies and consumer complaints has been attributed not to the technology itself but to installation quality — heat pump sizing, system design and commissioning genuinely require more specific expertise than a straightforward gas boiler swap, and the UK heat pump installer workforce has been expanding rapidly to meet growing demand, which has in some documented cases outpaced the availability of sufficiently experienced installers for a period. Choosing an MCS-certified installer with genuine, demonstrable heat pump experience specifically, rather than a general heating engineer newly qualified for heat pump work, is one of the most significant practical steps a homeowner can take to ensure the efficiency figures discussed throughout this piece are actually realised in their own specific installation. ## Frequently asked questions ### Can a heat pump work well in an older, poorly insulated UK home? It can, but typically requires additional work beyond simply swapping the boiler — improved insulation and appropriately sized radiators or underfloor heating are usually needed to get anywhere near the heat pump's rated efficiency, which is why a proper property assessment before installation is strongly recommended rather than a like-for-like swap. ### Is a heat pump always cheaper to run than a gas boiler? Not universally — it depends on the specific installation's achieved COP relative to the current electricity-to-gas unit price ratio, meaning a well-installed heat pump in a suitable home commonly does deliver running cost savings, while a poorly matched installation in an unsuitable property has in some documented cases shown little or no saving. ## Sources - [Energy Saving Trust — Heat pump efficiency and running costs](https://energysavingtrust.org.uk/) - [MCS — Heat pump installation standards](https://mcscertified.com/) --- Daily Junction — https://dailyjunction.org/science/heat-pumps-vs-gas-boilers-2026