The short answer
An air conditioner’s energy rating is shown on an energy label graded A+++ (best) to D, derived from its SEER (cooling) and SCOP (heating) seasonal efficiency figures. The higher the grade and the higher those numbers, the more cooling or heating the unit delivers per unit of electricity — and the cheaper it is to run. The label lets you compare similar-capacity models at a glance, but always cross-check the SEER, SCOP and stated annual energy use against the model’s own datasheet.
The energy label is the most useful single piece of information when comparing air conditioners, because it distils efficiency into a grade and a set of seasonal figures. Understanding it stops you paying to run an inefficient unit for a decade. This guide explains the A+++–D scale, the SEER and SCOP figures behind it, and how to read the label to estimate and compare running costs.
Energy ratings at a glance
- Scale A+++ (best) down to D
- Cooling figure SEER (seasonal cooling efficiency)
- Heating figure SCOP (seasonal heating efficiency)
- Higher figures Cheaper to run
- Also shown Annual energy use and noise
- Verify on The model’s datasheet
What the energy label shows
Air conditioners sold in the UK carry a standardised energy label. Its headline is a grade on a scale from A+++ at the top down to D, with a familiar colour band from green (efficient) to red (inefficient). The grade is calculated from the unit’s seasonal efficiency, so it is a fair comparison between models of similar capacity. Alongside the grade, the label typically shows the seasonal efficiency figures, an indicative annual energy consumption in kWh, and the unit’s sound levels — useful if noise matters.
SEER and SCOP — the figures behind the grade
Two seasonal numbers drive the label:
- SEER — the Seasonal Energy Efficiency Ratio for cooling. Higher means more cooling per unit of electricity.
- SCOP — the Seasonal Coefficient of Performance for heating, since most units are reversible. Higher means more heat per unit of electricity.
They are seasonal averages across a representative range of conditions, which makes them far more realistic than the older single-point EER and COP figures. A unit may carry separate grades for cooling and heating — worth noting if you intend to use both modes; see heating and cooling air con.
| On the label | Means |
|---|---|
| A+++ to D grade | Overall efficiency band (best to worst) |
| SEER | Cooling efficiency — higher is better |
| SCOP | Heating efficiency — higher is better |
| Annual kWh | Indicative yearly energy use |
Using the label to compare running costs
The grade tells you which of two similar units is cheaper to run, but to estimate actual cost you can use the indicative annual energy figure (in kWh) and multiply by your electricity unit rate — around 25p/kWh is a common 2026 reference, though you should check your own tariff against the unit rate you actually pay. A better-rated unit usually costs a little more up front but repays the difference through lower bills over its life, especially if it runs often.
Why the rating is worth paying attention to
Air conditioning is a long-lived purchase, often running for ten years or more, so a small efficiency difference compounds into a meaningful sum over time. Choosing a higher-rated, correctly sized inverter unit is the single most effective way to keep running costs down — far more than how you operate it day to day. This page is general information, not a site survey; a qualified installer can show you the energy label and datasheet for the exact model and capacity they recommend.
Separate ratings for heating and cooling
One point that trips people up is that a reversible unit can carry two efficiency stories. Its cooling performance is summarised by SEER and its heating performance by SCOP, and the corresponding grades need not be identical — a unit might be excellent at cooling but more ordinary at heating, or the reverse. If you intend to use both modes, read both grades rather than assuming a single headline figure covers everything.
For heating, the SCOP figure also depends on the climate band the manufacturer tested against, so compare like with like and look for the figure relevant to a UK “average” climate rather than a warmer one that flatters the result. The same care applies to the indicative annual energy consumption shown on the label: it is calculated against a standard usage assumption that may differ from how hard you will actually run the unit. Treat it as a fair basis for comparing two models, not a precise prediction of your bill. To turn these figures into pounds and pence for your own tariff and usage, see is air conditioning expensive to run and electricity usage.
Want to compare units on running cost?
An installer can show you the energy label, SEER and SCOP for each model they recommend so you can compare lifetime running costs, not just the purchase price. Ask for the figures for your exact capacity.
Frequently asked questions
What is a good energy rating for air conditioning?
A+++ is the top grade on the A+++–D scale, indicating the highest seasonal efficiency and lowest running cost for its class. Aim for the highest grade your budget allows, since the difference compounds over the unit’s life.
What do SEER and SCOP mean on the label?
SEER is the seasonal cooling efficiency and SCOP the seasonal heating efficiency. Both are seasonal averages, and higher numbers mean more cooling or heating per unit of electricity — so cheaper running.
Does a better energy rating save money?
Yes. A higher-rated unit delivers more cooling or heating per kWh, so it costs less to run. The up-front premium is usually repaid through lower bills, especially for units that run often.
How do I estimate running cost from the energy label?
Take the indicative annual energy figure in kWh from the label and multiply by your electricity unit rate (around 25p/kWh is a common 2026 reference). Check the figure against your own tariff for an accurate estimate.
Sources & further reading
- Energy Saving Trust — energy labels and home cooling guidance
- Ofgem — electricity unit price information
- Daikin — energy-label, SEER and SCOP datasheets (used as factual specification)
- Mitsubishi Electric — energy-label, SEER and SCOP datasheets (used as factual specification)
This guide is general information, not a site-specific survey or a substitute for a quote from an F-Gas-certified installer. Installation, servicing and refrigerant handling are legally restricted to F-Gas-certified engineers.