Split air conditioners up to 12 kW sold in Great Britain carry an energy label with two key numbers: SEER for cooling and SCOP for heating. They’re the most useful way to compare units, as long as you know what they measure and what they don’t.
SEER: seasonal cooling efficiency
SEER (seasonal energy efficiency ratio) is the cooling delivered over a standard cooling season divided by the electricity used. A SEER of 8 means 8 kWh of cooling for each 1 kWh of electricity. It is “seasonal” because it averages performance across a range of outdoor temperatures and part loads, not one test point. Higher is better.
SCOP: seasonal heating efficiency
SCOP (seasonal coefficient of performance) does the same for heating. A SCOP of 5 means 5 kWh of heat for each kWh of electricity. Labels give SCOP for an “average” climate and often a “warmer” one. For example, the Fujitsu/GENERAL Designer 2.5 kW lists 5.10 for average and 6.50 for warmer. In the UK, use the average figure.
What the energy classes mean
The classes come from Regulation 626/2011 (Annex II). For split air conditioners:
| Class | SEER (cooling) | SCOP (heating, average climate) |
|---|---|---|
| A+++ | 8.50 or more | 5.10 or more |
| A++ | 6.10 to under 8.50 | 4.60 to under 5.10 |
| A+ | 5.60 to under 6.10 | 4.00 to under 4.60 |
| A | 5.10 to under 5.60 | 3.40 to under 4.00 |
A unit can sit in different classes for cooling and heating. The Panasonic Etherea 4.2 kW, for instance, is A++ for cooling (SEER 7.10) but A+ for heating (SCOP 4.30). Always read both.
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A worked example: what the difference is worth
The label also gives an annual energy figure, based on standard test hours. The Fujitsu/GENERAL Designer 2.5 kW (data page) lists 95 kWh a year for cooling, at a SEER of 9.20. At Ofgem’s price cap unit rate of 26.32p per kWh (Direct Debit average, 1 October to 31 December 2026; Ofgem), that’s about £25 a year.
That figure equals 2.5 kW × 350 hours ÷ 9.20. A unit doing the same job at SEER 7.40 would use 875 ÷ 7.40 ≈ 118 kWh, about £31. So for cooling only, the gap is around £6 a year on label assumptions.
Heating is where efficiency pays. The same unit lists 658 kWh a year for heating at SCOP 5.10 (about £173), delivering about 3,356 kWh of heat. At SCOP 4.40 the same heat would take about 763 kWh, around £201. That’s a gap of roughly £28 a year, and more if you heat for longer than the label assumes.
The lesson: for summer-only cooling, a mid-range unit is usually the sensible buy. If you’ll heat with it, a higher SCOP is worth paying for. Our /air-conditioning-running-costs-uk-2026/ guide goes further.
Why your real figures will differ
- Sizing. An oversized unit cycles more and runs less efficiently.
- Installation. Long or poorly insulated pipe runs and a cramped outdoor position cut performance.
- Use. Very low set points and doors left open increase energy use.
- Maintenance. Dirty filters and coils reduce efficiency. See /air-conditioning-annual-service-what-is-included/.
Air conditioning and your EPC
An Energy Performance Certificate rates a building’s energy use and is produced by an accredited assessor using a standard government method. For homes, the main heating system has a big influence. An air-to-air heat pump used as the main heating may be treated differently from one used for occasional comfort, so ask your EPC assessor how a proposed system would be recorded before relying on any change in rating. The Energy Saving Trust notes that air-to-air heat pumps are sometimes referred to as air conditioning.
For businesses, larger air conditioning systems also bring inspection duties. See /tm44-inspection-explained/ and /tm44-inspections/.
How we use these numbers
At a site survey we size the system for your rooms, then show you the SEER and SCOP for two or three suitable models so you can see the trade-off between purchase price and running cost. Our brand reviews list the published figures for popular ranges: see /panasonic-air-conditioning-review-uk/ and /fujitsu-air-conditioning-review-uk/.
Quick answers
What is a good SEER rating?
8.50 or more is A+++ for split air conditioners, and 6.10 to under 8.50 is A++. Many premium wall units now publish SEER above 9.
What is a good SCOP for air conditioning?
5.10 or more (average climate) is A+++, and 4.60 to under 5.10 is A++. A high SCOP matters most if you’ll use the system for heating.
Does air conditioning improve an EPC rating?
It depends on how the system is used and recorded. Ask your EPC assessor before relying on a change in rating.
Related services
- Air conditioning installation
- Air-to-air heat pumps
- Air conditioning servicing
- TM44 air conditioning inspections
More advice
- How Much Does It Cost to Run Air Conditioning in the UK? 2026 Guide
- Best Air Conditioning Units for UK Homes 2026: Buyer’s Guide
- Heat Pump vs Air Conditioning: What’s the Difference?
- Air Conditioning in Winter: Using Heat Pump Mode Effectively
- All advice
This guide is general information, checked against the sources linked on 30 October 2026. It isn’t legal, tax or financial advice. Rules, grants and product ranges change, so check the current position before you rely on it.