Air Conditioning Energy Labels Explained (UK)

When you compare air conditioning or heat pump systems, you will see energy labels, letter grades and efficiency figures. They are useful, but they can be confusing, and they do not tell the whole story. This guide explains what the UK energy label on an air conditioner shows, how seasonal efficiency figures work, and why installation and use matter as much as the rating.

The UK energy label

Most air conditioners sold in the UK carry an energy label that grades efficiency on a lettered scale, with the most efficient products at the top. The label for a reversible split system typically shows separate information for cooling and heating, including:

• an efficiency class for cooling
• an efficiency class for heating, often for more than one climate zone
• the design capacity in kilowatts
• annual energy consumption figures based on standard assumptions
• sound power levels for indoor and outdoor units

The label lets you compare products on a like-for-like basis. It does not tell you how much a system will cost you to run in your specific home.

Seasonal efficiency, not peak efficiency

Older systems were often rated on a single test point. Modern ratings use seasonal figures, which average performance over a range of conditions to reflect a typical year. For cooling, manufacturers publish a seasonal energy efficiency ratio, and for heating, a seasonal coefficient of performance (SCOP). In both cases, the higher the number, the more cooling or heating you get for each unit of electricity.

Because UK cooling demand is moderate for much of the year and heating is often the bigger use, it is worth paying attention to the heating figure, not just cooling. Check which climate zone the heating figure applies to; ratings for an average climate are the most relevant guide for most of England.

What else affects real-world efficiency

Sizing

A unit that is too large or too small for the room will not achieve its rated efficiency. Inverter systems work best when they can run steadily at part load, which needs correct sizing.

Installation quality

Pipe length, correct refrigerant charge, proper pressure testing and evacuation, good airflow around the outdoor unit and neat condensate drainage all affect performance. A highly rated unit installed poorly can perform worse than a mid-rated unit installed properly.

Use and settings

Setting cooling to extreme temperatures, running with windows open, or switching the system hard on and off reduces efficiency. Moderate set points and scheduling help.

Maintenance

Dirty filters and coils reduce airflow and efficiency. Regular cleaning and servicing keep the system close to its rated performance. Our servicing ranges from £179 to £389 depending on the system.

Regulations behind the ratings

Minimum efficiency requirements for air conditioners sold in Great Britain are set through ecodesign and energy labelling rules, which have been carried over from EU law and are now managed by the UK government. For fixed building services, Part L of the Building Regulations in England sets expectations for efficiency, controls and commissioning when systems are installed or replaced. The details are updated periodically, so check the current Approved Document if you need specifics.

For commercial buildings with larger air conditioning systems, energy inspection requirements also apply; read our TM44 inspection guide.

Refrigerant and efficiency

Most new split systems now use R32, which has a much lower global warming potential than older refrigerants such as R410A and works efficiently in modern equipment. Refrigerant choice is regulated under the GB F-Gas Regulations, and all installation work must be carried out by F-Gas certified engineers. See our F-Gas phase-down guide for more.

Upgrading an older system

If your system is ten or more years old, a modern inverter system is likely to be considerably more efficient. Combined with better controls, that can make a real difference to comfort and running costs. Before replacing anything, though, we check whether the existing system can be improved with servicing or settings. Our guide to upgrading your air conditioning explains the options.

Using ratings sensibly

• Use the label to compare products of similar capacity.
• Look at the heating figure as well as cooling.
• Check sound levels, especially for bedrooms.
• Remember that sizing, installation and maintenance determine real results.
• Ask your installer to explain why a particular model suits your room.

How we choose systems

We recommend systems based on a survey of each room, not just the headline rating. We look at insulation, glazing, orientation and how you use the space, then choose an efficient model at the right size. Installations start from £1,300, and domestic air conditioning is currently zero-rated for VAT. Read more on our air conditioning installation page, or about homes we look after in Sudbury.