SEER and SCOP Explained

SEER and SCOP are the efficiency ratings you see on air conditioning energy labels and specification sheets. They tell you how much cooling or heating a system delivers for the electricity it uses, measured over a typical season. Higher numbers mean lower running costs.

What SEER Means

SEER stands for seasonal energy efficiency ratio. It compares the cooling a system provides over a typical cooling season with the electricity it uses. A SEER of 8 means the system delivers around 8 units of cooling for every unit of electricity, averaged across the season.

What SCOP Means

SCOP stands for seasonal coefficient of performance. It does the same job for heating, comparing the heat delivered over a typical heating season with the electricity used. A SCOP of 4 means around 4 units of heat for every unit of electricity.

Seasonal figures are more useful than single-point figures such as EER and COP, which are measured at one set of conditions. Seasonal ratings take account of the system running at part load and across a range of outside temperatures, which is how inverter systems spend most of their time. Our guide on how air conditioning works explains why.

The Energy Label

Air conditioners up to 12 kW sold in Great Britain currently carry an energy label rated from A+++ (best) to D. Systems that heat as well as cool have separate ratings for cooling and heating. For split systems, the bands are:

• A+++: SEER of 8.5 or more, SCOP of 5.1 or more

• A++: SEER from 6.1 to 8.5, SCOP from 4.6 to 5.1

• A+: SEER from 5.6 to 6.1, SCOP from 4.0 to 4.6

• A: SEER from 5.1 to 5.6, SCOP from 3.4 to 4.0

• B to D: lower ratings, down to a SEER of 3.6 and a SCOP of 2.5

The label also shows the rated capacity in kW, the estimated annual electricity use in kWh and the noise levels of the indoor and outdoor units. For heating, it always shows a rating for an average European climate, and some labels also show ratings for warmer and colder climates.

What Ratings Should You Look For?

For a home system, A++ or A+++ for cooling is a sensible target. If you plan to use the system for heating, look closely at the heating rating too. A system used for heating normally runs for more hours each year than one used only for cooling. The most efficient wall units reach A+++ for both cooling and heating.

Ratings Are Not the Whole Story

• Size. A unit that is too big or too small for the room will not reach its rated efficiency. See what size air conditioner you need.

• Installation. Pipe length, the correct refrigerant charge and a good outdoor unit position all affect real-world performance.

• How you use it. Sensible temperature settings and timers also make a real difference to your bills. See air conditioning remote symbols and modes.

• Maintenance. Dirty filters and coils reduce efficiency. See how to clean your air conditioner.

How Efficiency Affects Running Costs

Running cost depends on the electricity used, so a higher SEER or SCOP means a lower bill for the same cooling or heating. For example, a system with a SCOP of 5 uses about 20% less electricity for the same heat than one with a SCOP of 4. Our guide to air conditioning costs covers running costs.

Frequently Asked Questions

Is SEER the same as EER?

No. EER is measured at one set of conditions. SEER is averaged over a whole season, including part-load running, so it better reflects real use.

What is a good SCOP?

For a split system, a SCOP of 4.6 or more puts it in the A++ band for heating, and 5.1 or more puts it in the A+++ band.

Are portable air conditioners rated the same way?

No. Portable units are rated using EER and COP rather than seasonal figures, so you cannot compare them directly with split systems. See do portable air conditioners work?

Call 01772 288651 or use the form below to book a free survey. We will measure the room, recommend the right system and give you a clear written quote.

Last updated: November 2026.