Glossary · Heat pumps, grants and regulations
What are COP and SCOP?
COP (coefficient of performance) is the heat a heat pump delivers divided by the electricity it uses at one moment. SCOP (seasonal coefficient of performance) is the same ratio averaged over a whole heating season. A SCOP of 4 means four units of heat for each unit of electricity.
Key points
- COP is a snapshot of efficiency at one set of conditions. SCOP averages it across a heating season, so it is the fairer figure for comparing units.
- A SCOP of 4 means 1 kWh of electricity produces 4 kWh of heat, which Daikin also describes as 400 percent efficiency.
- Daikin gives air source heat pumps a typical SCOP of 3 to 4 and condensing gas boilers 0.99 to 1.09.
- SCOP falls in colder weather and when the heating water has to be hotter, so a quoted figure is not what every home will get.
- The official SCOP definition used for the government's Energy Technology List follows the BS EN 14825 test method.
How COP and SCOP work
A heat pump moves heat from the air, ground or water into your home instead of making heat by burning fuel.[1]Daikin UK, How does a heat pump work? That is why it can deliver more heat than the electricity it uses. The ratio of heat out to electricity in is its coefficient of performance.
COP is the ratio at one moment, under one set of conditions. SCOP is the seasonal version. The government’s Energy Technology List defines SCOP as the overall coefficient of performance of a heat pump using electricity, representative of the heating season, worked out as the reference annual heating demand divided by the annual energy used for heating.[2]DESNZ, Energy Technology List: Air to Water Heat Pumps The measurements follow the BS EN 14825 standard for an average heating season.[2]DESNZ, Energy Technology List: Air to Water Heat Pumps
Daikin gives a simple example. If 1 kWh of electricity produces 4 kWh of heat, that is a SCOP of 4, or an efficiency of 400 percent.[1]Daikin UK, How does a heat pump work?
Typical figures
| Heat source | Typical SCOP quoted by Daikin |
|---|---|
| Air source (air to water) | 3.0 to 4.5 |
| Ground source | 4.0 to 5.0 or more |
| Condensing gas boiler, for comparison | 0.99 to 1.09 |
The first two rows come from Daikin’s guide to heat pump types.[4]Daikin UK, Types of Heat Pumps: Which One Is Right for Your Home? The boiler range comes from its guide to how heat pumps work, which describes modern condensing boilers as running at 99 to 109 percent efficiency.[1]Daikin UK, How does a heat pump work? These are one manufacturer’s figures. Check the SCOP on the product’s own data sheet.
What lowers a SCOP
Two things matter most. The first is weather. Daikin says a heat pump works harder in winter, so electricity use rises and efficiency falls in colder months.[3]Daikin UK, Heat pump power consumption guide The second is the temperature of the water in the heating system. Lower flow temperatures reduce the workload and improve SCOP.[3]Daikin UK, Heat pump power consumption guide Daikin notes that radiators may need upgrading, with larger ones running at a lower flow temperature, to avoid pushing the heat pump to high temperatures that eat into savings.[3]Daikin UK, Heat pump power consumption guide See flow temperature and weather compensation.
Example
Imran compares two quotes for a heat pump for his terrace in Keighley. One data sheet lists a SCOP of 3.2 and the other 4.0. At 4.0, each 1 kWh of electricity gives 4 kWh of heat. At 3.2, it gives 3.2 kWh. Over a season the second unit needs about a fifth less electricity for the same heat. Imran also asks which flow temperature each figure was measured at, because a SCOP at a low flow temperature will not hold for a system that has to run hot.
What people get wrong
A high SCOP on a brochure does not guarantee that figure in your home. It is a seasonal average measured under standard conditions, and the result depends on the system design, insulation and flow temperature.
Cooling has its own measure, SEER. SCOP only covers heating. Some people also treat COP and SCOP as interchangeable. COP is a single reading, and comparing one unit’s best-case COP with another’s SCOP is not a like-for-like test.
The bottom line
COP shows how well a heat pump performs at one moment. SCOP averages that performance across a heating season, which makes it the better figure for comparing units. A SCOP of 3 to 4 means three to four units of heat for each unit of electricity, against roughly one for a condensing boiler. Treat the number as a guide and ask your installer what flow temperature it assumes.
Common questions
What is a good SCOP for a heat pump?
Daikin says air source heat pumps typically reach a SCOP of 3 to 4, and ground and water source systems can exceed 4. A higher SCOP means less electricity for the same heat, but the figure depends on the flow temperature used.
What is the difference between COP and SCOP?
COP compares heat output with electricity input at one moment. SCOP is calculated across a whole heating season, so it allows for colder and milder days and is the better guide to yearly electricity use.
Can a heat pump really be more than 100 percent efficient?
Yes, because it moves heat rather than making it. Daikin says 1 kWh of electricity can deliver 4 kWh of heat, a SCOP of 4 or 400 percent. A gas boiler cannot go above about 100 percent.
Does SCOP stay the same all year?
No. SCOP is a seasonal average. Daikin says a heat pump works harder in winter, so electricity use rises and efficiency drops in cold weather, while lower flow temperatures improve the result.
Sources
We cite the original source for every figure: government, regulators, standards bodies and manufacturers' own documents. Each one shows the date we last checked it.
- Daikin UK. How does a heat pump work?. Checked 11 November 2026. ↩
- DESNZ. Energy Technology List: Air to Water Heat Pumps. Checked 11 November 2026. ↩
- Daikin UK. Heat pump power consumption guide. Checked 11 November 2026. ↩
- Daikin UK. Types of Heat Pumps: Which One Is Right for Your Home?. Checked 11 November 2026. ↩