TM44 Air Conditioning Inspections Explained

If you own or manage a commercial building with air conditioning, you may have a legal duty to have it inspected for energy efficiency. These inspections are commonly known as TM44 inspections, after the CIBSE guidance used to carry them out. This guide explains in general terms who needs one, what it involves and how it fits with regular servicing. Always check current government guidance for your specific situation.

What is a TM44 inspection?

Under the Energy Performance of Buildings Regulations in England and Wales, air conditioning systems with an effective rated output of more than 12kW must be inspected by an accredited energy assessor at regular intervals, at least every five years. The inspection looks at the energy efficiency of the system and whether it is suitably sized for the cooling needs of the building, and provides advice on improvements. The resulting report is lodged on the official register. Scotland and Northern Ireland have their own equivalent rules.

The CIBSE TM44 document sets out the methodology assessors use, which is why the inspection and report are widely known as TM44.

Who is responsible?

The duty usually falls on the person who controls the operation of the air conditioning system, which may be the building owner, the tenant or a managing agent, depending on the lease and management arrangements. It is worth checking who holds the responsibility for your building, because enforcement action can be taken where a valid inspection report is not in place.

Does your system count?

The 12kW threshold refers to the total effective rated output of the air conditioning systems in the building under the control of the same person, not each individual unit. Several smaller split systems in one building can add up to more than 12kW. The rules generally cover systems used for cooling; for detailed questions about what counts, such as reversible heat pump systems or process cooling, check the government guidance or ask an accredited assessor.

Most homes do not need a TM44 inspection; it is primarily relevant to offices, shops, hospitality, schools, healthcare and other non-domestic buildings.

What does the inspection involve?

An accredited energy assessor will usually:

• review records, including maintenance and refrigerant records
• inspect the indoor and outdoor equipment
• assess controls, time settings and set points
• look at the cooling loads and whether the system is appropriately sized
• identify opportunities to improve efficiency, such as maintenance, control changes or upgrades

The report gives recommendations rather than mandatory requirements, but acting on them often saves energy and money.

How TM44 differs from servicing and F-Gas checks

TM44 inspections are about energy efficiency and are carried out by accredited energy assessors. They are separate from:

• Routine servicing, which keeps the system clean, reliable and efficient.
• F-Gas leak checks, which are required at set intervals for systems above certain refrigerant thresholds and must be carried out by F-Gas certified engineers. See our F-Gas phase-down guide.

All three work together. Good maintenance records make a TM44 inspection simpler, and servicing is often the first step in acting on an inspection report.

Preparing for an inspection

• Gather information on all air conditioning systems in the building, including make, model, capacity and refrigerant.
• Collect maintenance and F-Gas records.
• Make sure the assessor can access plant rooms, roofs and indoor units.
• Have details of controls and building management systems available.
• Check when the previous report was lodged, if there was one.

Acting on the recommendations

Common recommendations include cleaning coils and filters, improving controls and time schedules, adjusting set points, fixing refrigerant leaks and replacing old, inefficient equipment, particularly where it uses refrigerants affected by the F-Gas phase-down. Replacement equipment should meet Part L expectations for efficiency, controls and commissioning.

How we help

We are not energy assessors, but we work alongside them. We service and maintain commercial air conditioning, keep clear records that support inspections and F-Gas compliance, and carry out the improvements recommended in reports, from control changes to full system replacement. Commercial servicing and upgrades are quoted after a survey.

Find out more on our commercial air conditioning and air conditioning servicing pages, or read about the businesses we look after in Bury St Edmunds.

A worked example

Imagine a small office with four wall-mounted split systems, each rated at around 3.5kW of cooling, all controlled by the same tenant. Individually, none of them is large, but together their effective rated output is above 12kW, so an inspection is likely to be required. If the same building had two separate tenants each controlling two of the units, the position could be different. Situations like this are why it is worth confirming the details with an accredited assessor.

Where to find the official rules

Government guidance on air conditioning inspections, including how to find an accredited assessor and lodge reports, is published on GOV.UK. Because guidance is updated from time to time, check the current version rather than relying on older summaries.