Heat Pump Efficiency 2026: COP, SCOP & Savings

Heat pumps move heat rather than generate it, so their efficiency determines your running costs more than almost any other factor. A system that extracts three or four units of heat for every unit of electricity it consumes will cost far less to run than one managing only two. This guide explains the metrics that matter, what affects real-world performance and how grants can help.

Why Heat Pump Efficiency Matters More Than Upfront Cost

Running costs depend on how much heat you extract per kilowatt-hour of electricity.

Electricity use is a major part of a heat pump's lifetime cost. Two systems with identical upfront costs can differ by hundreds of pounds a year in running costs if one operates more efficiently. The Energy Saving Trust notes that air-source heat pumps transfer heat from outside air into water for space heating, and system design, heat loss and flow temperature all determine how well they do this (Energy Saving Trust, air-source heat pumps).

Illustrative example (hypothetical, for budgeting only): Assume a home needs 12,000 kWh of heat per year and electricity costs 24.5p/kWh. A heat pump with a seasonal COP of 3.0 would use roughly 4,000 kWh of electricity, costing about £980. The same home with a seasonal COP of 3.8 would use roughly 3,158 kWh, costing about £774. That is a difference of around £206 per year from efficiency alone. These figures are not measured data; actual costs depend on your tariff, property and usage.

What Is a Good COP and SCOP for a Heat Pump in the UK?

COP measures heat output divided by electricity input at a single test point.

The coefficient of performance (COP) tells you how many kilowatts of heat a pump delivers for each kilowatt of electricity consumed. A COP of 3.5 means 3.5 kW of heat per 1 kW of electricity. However, COP is measured at fixed laboratory conditions and changes with outdoor temperature and flow temperature.

SCOP (seasonal coefficient of performance) is more useful for UK buyers. It averages performance across a typical heating season under the EN 14825 test standard. For example, NIBE advertises an SCOP above 5.0 for the F2120-16 and F2120-20 under EN 14825 average-climate, low-temperature conditions (NIBE, F2120). Real household performance will differ because test conditions do not replicate every home's heat loss, radiator sizing or hot-water demand.

Compare SCOP values only at matching climate and water-temperature conditions. A product test value is not a measurement of your home. For an installed system, compare measured seasonal performance with its design estimate using the same metering boundary.

Ground-source heat pumps often achieve higher SCOPs because ground temperature is more stable than air temperature through winter.

How Your Home's Insulation Affects Heat Pump Performance

Better insulation means lower flow temperatures and higher efficiency.

Heat pumps work most efficiently when they supply water at lower temperatures, typically 35°C to 45°C rather than the 60°C to 70°C a gas boiler might use. A poorly insulated home loses heat quickly, so the system must work harder and run at higher flow temperatures to keep rooms warm. This directly reduces COP.

The most important insulation measures for heat pump performance are:

• Loft insulation: The Energy Saving Trust recommends 270 mm of mineral wool for loft insulation, which can last around 40 years if correctly installed (Energy Saving Trust, loft insulation). Topping up from older, thinner levels is often the cheapest single improvement.
• Wall insulation: Heat loss depends on wall construction and any existing insulation. Both cavity wall and internal wall insulation reduce heat loss and allow lower flow temperatures.
• Draughts and windows: Sealing gaps and upgrading to double or triple glazing reduces the peak heat demand your system must meet.

Insulating before or alongside a heat pump installation is not a grant eligibility requirement for the Boiler Upgrade Scheme (the previous loft and cavity insulation condition was removed in May 2024). However, it remains sensible advice because it can allow a smaller, cheaper heat pump to be specified and will improve the system's seasonal efficiency.

Which Grants Can Help You Improve Heat Pump Efficiency in 2026?

The Boiler Upgrade Scheme covers heat pump installation in England and Wales.

The BUS provides £7,500 towards an air-to-water or ground-source heat pump. Off-gas-grid properties replacing oil or LPG heating can receive £9,000 (this uplift is available until March 2027). Air-to-air heat pumps qualify for £2,500 and biomass boilers for £5,000. Fossil-fuel hybrid systems do not qualify as the new installation. You must own the property, use an MCS-certified installer and have the system commissioned within 120 days of applying. Most new builds and social housing are excluded (GOV.UK, BUS grant categories).

BUS funding is confirmed through fiscal year 2029/30 under the Warm Homes Plan, though this is a funding commitment rather than a guaranteed application deadline.

ECO4 runs until 31 December 2026 and can fund insulation measures (and in some cases heating) for eligible low-income households. Eligibility depends on benefits, tenure, EPC rating and the measures proposed. ECO4 Flex is a council referral route, not guaranteed funding.

The Warm Homes Local Grant covers private homes in England rated EPC D to G, usually where household income is at most £36,000 (qualifying benefits or postcodes can provide alternative routes). Council surveys and available funding determine which improvements are offered. A national application portal exists at GOV.UK. Funding delivery runs to March 2028.

Scotland has separate support programmes; exclusion from BUS does not mean no Scottish funding is available. See Energy Grants Scotland for details.

Installed energy-saving materials (including heat pumps and insulation fitted by a professional) currently qualify for zero-rate VAT through 31 March 2027, after which the rate is scheduled to rise to 5%.

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Common Reasons Heat Pumps Underperform and How to Fix Them

Most efficiency problems come from system design or settings, not the heat pump itself.

Oversized or undersized systems. A heat pump sized by bedroom count rather than a proper heat-loss calculation may cycle on and off too frequently (oversized) or struggle to meet demand (undersized). Both reduce seasonal efficiency. A qualified MCS installer should complete a room-by-room heat-loss survey before specifying equipment.

Flow temperature set too high. If the installer left the flow temperature at 55°C or above to compensate for small radiators, the COP drops significantly. Upgrading key radiators or adding a few extra allows the flow temperature to come down to 40°C to 45°C, with the improvement depending on the equipment and operating conditions.

Poor defrost cycling. Air-source heat pumps periodically reverse to defrost the outdoor unit. Excessive defrosting, often caused by restricted airflow around the unit, wastes energy. Keep the area around the outdoor unit clear of plants, fencing and debris.

Supplementary electric heating running unnoticed. Some systems include a backup immersion heater or electric element that activates when the heat pump cannot cope. If this runs frequently, it consumes electricity at a COP of 1.0, dragging down overall efficiency. Check your electricity consumption patterns or ask your installer to review the settings.

Lack of weather compensation. A weather-compensation curve adjusts flow temperature automatically based on outdoor conditions. Without it, the system may run at a fixed, unnecessarily high temperature on mild days.

How to Check Whether Your Heat Pump Is Running Efficiently

Compare your electricity use against heat delivered over a full heating season.

The most reliable way to assess real-world efficiency is to measure seasonal performance factor (SPF). You need two readings: total electricity consumed by the heat pump (from a dedicated meter or smart monitor) and total heat delivered (from a heat meter, which many MCS installations include).

Divide heat delivered (kWh) by electricity consumed (kWh) over a full year. Include the same period and system boundary in both readings, and account for auxiliary pumps and backup heaters. Compare the result with the design expectation rather than treating one universal threshold as proof of a fault.

Practical steps you can take:

• Read your heat meter at the start and end of the heating season. Many modern controllers display cumulative figures.
• Track electricity use on the heat pump circuit separately from the rest of the house. A clamp meter or smart energy monitor can help.
• Review flow temperatures on the controller. If they regularly exceed 50°C, ask your installer whether radiator upgrades could allow a reduction.
• Book an annual service. Refrigerant charge, fan condition and control settings should all be checked. An MCS installer can benchmark your system against expected performance.

If your system consistently underperforms, the installer who commissioned it should be your first contact. The MCS certification scheme provides a consumer code and complaints process.

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