UK heat pump marketing rarely uses the SEER and HSPF ratings common in the US; here, efficiency is measured using SCOP (Seasonal Coefficient of Performance) and COP (Coefficient of Performance). Knowing which metric you're actually looking at matters when comparing models.

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What's the most energy-efficient heat pump for my home?

There's no single answer, since the right choice depends on your home's size, heating needs, budget, and local climate. When comparing options, look at:

• SCOP (Seasonal Coefficient of Performance): the UK and EU standard efficiency metric, averaging performance across a full heating season rather than a single moment, giving a more realistic picture than a snapshot COP figure.

• COP (Coefficient of Performance): the ratio of heat output to electricity input at a specific point in time, useful for understanding peak performance but less representative of real-world seasonal running.

• The size of the unit: undersized units struggle to heat the whole home; oversized units waste energy and can reduce comfort through short, inefficient cycling.

Variable-speed compressors let a heat pump adjust its output to match demand more precisely, generally improving real-world efficiency over single-speed units.

A qualified heat pump installer can help you choose the right size and type for your specific home.

What makes heat pumps so efficient?

A heat pump transfers heat from one place to another (typically from outside air, the ground, or a water source) rather than generating heat by burning fuel. Even in cold weather, there's still enough heat in the outside air to extract and bring indoors.

Gas boilers typically have an efficiency of around 90-94% (a "coefficient of performance" close to 1), while heat pumps can achieve a SCOP of 3 to 4, meaning they produce 3-4 units of heat for every unit of electricity used.

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Air source heat pump efficiency

Air source heat pumps extract heat from the outside air and transfer it indoors, and have become an increasingly popular alternative to gas boilers thanks to their efficiency and lower environmental impact.

See our air source heat pump cost guide for current pricing.

Getting the most from an air source heat pump

• Choose the right size for your home. An undersized unit works harder than necessary, reducing efficiency.

• Use a reputable manufacturer and MCS-certified installer. This affects both day-to-day efficiency and the unit's lifespan.

• Keep up with maintenance. Cleaning the outdoor unit and checking filters regularly keeps performance up.

Well-specified air source heat pumps can reach a SCOP of up to 4, meaning roughly 4 units of heat for every unit of electricity used, a significant improvement over a typical gas boiler.

Air-to-air heat pumps

A type of air source heat pump using fans to circulate warm air directly, rather than heating water for radiators or underfloor heating.

Generally less efficient than air-to-water or ground source systems, but cheaper to install, and they run most efficiently when outdoor temperatures stay above freezing.

If your radiators feel undersized for a heat pump system, you may need input from a central heating engineer as well as your heat pump installer to get sizing right.

Ground source heat pump efficiency

Ground source heat pumps extract heat from the ground rather than the air, and can be more efficient still, with some systems reaching a SCOP of up to 5.

Because the ground stays at a more stable temperature year-round than the air, ground source systems tend to perform more consistently in cold weather. They cost more to install than air source systems, but often deliver stronger long-term savings.

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What affects heat pump efficiency in practice?

Temperature difference

The bigger the gap between indoor and outdoor temperature, the harder your heat pump works, and the less efficient it becomes. This is why ground source systems, drawing from a more stable source, often hold their efficiency better in very cold weather.

Sizing

An undersized heat pump struggles to keep your home comfortable; an oversized one wastes energy and money.

Insulation and air sealing

A well-insulated, well-sealed home reduces how hard your heat pump needs to work, directly improving real-world efficiency. This matters more for heat pumps than gas boilers, since heat pumps typically run at lower flow temperatures.

Maintenance

Regular servicing, including filter changes and checking refrigerant levels, keeps efficiency up over the system's lifetime.

What's the most efficient way to run a heat pump?

Set your thermostat sensibly, and leave it alone

Aim for 18-21°C in winter. Make small adjustments (a degree or two at a time) rather than large swings, and give the system time to respond.

Don't switch it off when you're out

Unlike a gas boiler, turning a heat pump off entirely often costs more overall, since it then has to work much harder to bring your home back up to temperature. Turning the thermostat down a few degrees while you're out is generally more efficient than switching off entirely.

Keep filters and coils clean

Clogged filters and dirty outdoor coils reduce efficiency and can shorten the system's lifespan. Most manufacturers recommend checking filters every one to three months.

Book annual servicing

A professional service, checking refrigerant levels, filters, and coils, keeps your system running at its best. Most manufacturers and installers recommend this at least once a year.

Use a smart or programmable thermostat

Scheduling different temperatures for different times of day helps balance comfort and running costs without manual adjustment.

Use auxiliary or backup heat sparingly, if fitted

Some systems include backup heating for very cold spells. Relying on this often points to an undersized heat pump or insufficient home insulation, both worth addressing rather than working around long-term.

Ground source heat pump cost: 2026 price guide

With the growing popularity of green energy solutions in the UK, many homeowners are looking for alternative heating options for their homes – such as ground source heat pumps. In this guide we look at the average ground source heat pump cost in the UK.

Learn more

How much can a heat pump save on energy bills?

Savings depend heavily on your current system, home insulation, and current gas and electricity prices, which shift regularly.

Rather than quoting a fixed saving figure that will likely be out of date by the time you read this, check our gas vs electric heating cost guide for a current comparison, and ask an installer for a saving estimate specific to your home.

Before you choose a heat pump

• Confirm SCOP (not just COP) when comparing models

• Get the unit sized correctly for your home, not oversized or undersized

• Check your home's insulation is adequate before committing

• Use an MCS-certified installer, especially if applying for the Boiler Upgrade Scheme

• Compare current running cost estimates rather than relying on older published figures

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