SCOP and COP in Plain English — What Heat Pump Efficiency Means for Your Bills
Last reviewed: 2 October 2026
A plain-English explanation of heat pump efficiency numbers, with a simple way to turn them into a heating bill for a Leicester home — and a comparison with gas and storage heaters.
The simple idea
Efficiency numbers tell you how many units of heat you get for each unit of electricity.
- A storage heater: 1 (one in, one out)
- A gas boiler: just under 1 per unit of gas
- A heat pump: typically 3 to 4
That’s why a heat pump can be cheaper to run even though electricity costs more per unit than gas.
COP: efficiency right now
COP (coefficient of performance) is the efficiency at one moment. It changes with the weather: higher on a mild day, lower on a frosty one. Brochures quote COPs measured in mild test conditions, so they can look higher than what you’ll get across a winter.
SCOP: efficiency over a year
SCOP (seasonal coefficient of performance) is the average across a whole heating season. This is the number to use for working out your bill.
Your bill in three steps:
- Take your home’s yearly heat demand. For a typical three-bed Leicester semi, around 11,000 kWh.
- Divide by the SCOP. At 3.2: 11,000 ÷ 3.2 ≈ 3,440 kWh of electricity.
- Multiply by your electricity price. At about 26p: ≈ £905 a year. On a heat pump tariff averaging about 18p: ≈ £620.
How that compares
For the same 11,000 kWh of heat at October 2026 prices:
| Heating | Yearly cost (approx.) |
|---|---|
| Storage heaters | £2,000–£2,300 |
| Gas boiler, including standing charge | £1,080 |
| Heat pump, SCOP 3.2, standard tariff | £905 |
| Heat pump, SCOP 3.2, heat pump tariff | £620 |
What SCOP to expect in Leicester
Leicester’s winters are a little colder than the South West’s, so a heat pump here works slightly harder. A well-designed system typically averages 3.0–3.5:
- interwar semis with filled cavities: towards the top of that range
- Victorian terraces: middle of the range, with a few larger radiators
- big villas run at higher water temperatures: towards the bottom
What pushes SCOP up
- Lower water temperature in the radiators (see flow temperature)
- Correct sizing so it isn’t switching on and off
- Leaving it running steadily
- A clean outdoor unit with nothing stacked against it in the yard
- A scale-free cylinder coil — Leicester’s hard water makes this worth checking at the annual service
And HSPF?
HSPF is an American rating, mostly for air-to-air units, measured in different units. You can ignore it for a UK heat pump with radiators. Ask for the SCOP.
Related: running costs compared · will a heat pump pay for itself?
See what a heat pump would look like in your Leicester home
The mechanism is the same in every UK home; the design is specific to yours. Our team carries out a free in-home survey including a full room-by-room heat-loss calculation, identifies the system size and configuration that fits your property, and provides a written quote with the £7,500 BUS grant already deducted.
You'll see the actual figure you'd pay — not an estimate — and the projected efficiency for your specific install.