TM44 Air Conditioning Inspections: What Building Managers Need to Know

What a TM44 inspection is

“TM44” is the common name for the air conditioning inspection required by the Energy Performance of Buildings (England and Wales) Regulations 2012. The name comes from CIBSE’s technical memorandum TM44, which sets out the assessment method that accredited assessors follow.

The inspection is about energy efficiency. The assessor looks at how efficient the system is likely to be, whether it is the right size for the cooling load, how well it is controlled and maintained, and what could be improved or replaced. The result is a report lodged on the national Energy Performance of Buildings Register, with a unique reference number.

The rules described here apply in England and Wales. Energy performance of buildings is devolved, and Scotland and Northern Ireland have their own arrangements.

Does your building need one?

A system needs inspecting if its effective rated output is more than 12 kW. In practice:

The output figure is the manufacturer’s rated cooling output, not the electrical input. Your asset register, the units’ data plates or the original installation documents will usually give it. If you do not have a reliable asset list, a system assessment is a sensible first step.

GOV.UK guidance updated in November 2026 also makes clear that mechanical ventilation serving a conditioned zone, including air handling units and heat recovery systems, must be included in the inspection.

How often, and when the clock starts

• The first inspection must take place within five years of the system first being put into service.
• After that, inspections must be no more than five years apart.
• The inspection covers the whole system, including any parts less than five years old.
• If control of a system passes to a new person without the previous report being handed over, the system must be inspected within three months of the change.

Who is responsible

The duty sits with the “relevant person”: whoever controls the technical functioning of the system. That is not someone who only adjusts the temperature.

• The owner usually controls the system, even if day-to-day operation is contracted out.
• Under a full repairing and insuring lease, the occupier usually controls it.
• A facilities management or servicing contract can make the contractor responsible for arranging inspections, but the landlord or occupier keeps a parallel duty.
• Where an occupier installs its own units, it owns them and the duty is the occupier’s.

The relevant person must make sure inspections happen on time, keep the most recent report, and pass it on to anyone who takes over control of the system.

What the report covers

A TM44 report must include, as a minimum:

• the likely efficiency of the system and suggestions for improvement
• faults found during the inspection and suggested actions
• the adequacy of maintenance
• the adequacy of the installed controls and settings
• the size of the system compared with the cooling load
• how well the system can optimise its performance under typical operating conditions
• a summary of findings and key recommendations

There is no legal requirement to act on the recommendations. Many of them, such as correcting time schedules, stopping heating and cooling running at the same time, or cleaning neglected coils, are low-cost and reduce running costs.

How it fits with servicing and F-gas checks

Building managers often confuse three separate things:

A TM44 assessor does not carry out cleaning, repairs or adjustments as part of the inspection. That work is done by your maintenance contractor.

Preparing for an inspection

You will get a more useful report, and a quicker inspection, if you can provide:

• An up-to-date list of air conditioning and mechanical ventilation equipment, with locations and rated outputs
• Service records and the F-gas log for each system
• Controls information: BMS schedules, setpoints and zone layouts
• Safe access to outdoor units, plant rooms and representative indoor units
• The previous TM44 report, if there is one

The GOV.UK guidance notes that where a system is well documented and regularly maintained to a good standard, the inspection and report can be more focused.

Acting on the recommendations

After the report, prioritise:

1. No-cost changes to schedules, setpoints and deadbands.
2. Maintenance actions: cleaning coils, replacing filters, fixing failed sensors and valves.
3. Investment items: controls upgrades, replacing old or oversized equipment, or moving to lower-GWP refrigerants.

We do not carry out TM44 inspections, which must be done by an accredited energy assessor. We can help you act on a report’s maintenance, repair and controls recommendations through commercial air conditioning services, HVAC controls work and planned maintenance contracts.