Air conditioning fitted into a commercial building carries a legal obligation that many owners discover only when a solicitor or an auditor asks for the paperwork. TM44 inspections are assessments of air conditioning systems, carried out by an accredited assessor and lodged on the national register.
The duty sits within the Energy Performance of Buildings Regulations and applies across England and Wales. Scotland and Northern Ireland run parallel regimes under their own legislation. TM44 inspections take their name from the CIBSE guidance document that sets out how the assessment should be done.
Which Systems Fall Within Scope
The threshold is an effective rated output above 12kW. That figure means the maximum cooling output the manufacturer specifies for continuous operation, and it appears on the rating plate, in the operating manual or on the manufacturer’s website.
Here is where buildings get caught out. The threshold applies to the combined output of every unit under one person’s control rather than to units taken individually. A small office with four wall-mounted splits at 4kW apiece sits inside the scope even though nothing in the building comes close to 12kW on its own. Where one party controls the temperature across several units, those units count as components of a single system and their outputs are added together.
Confirming the figure matters more than estimating it. Rating plates weather, units get swapped out piecemeal over the years, and a maintenance contractor’s schedule of assets is often the quickest route to a reliable total.
The rules cover systems that use a refrigerant for cooling. Buildings relying on natural ventilation or on simple extract fans fall outside them.
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Who Holds the Legal Duty
Responsibility rests with the person who controls the operation of the system. That phrasing matters, because it does not automatically point at the freeholder.
In a multi-let office the managing agent usually controls the plant and carries the duty with it. In a single-let building on a full repairing lease the tenant may control it instead. Leases are often silent on the point, and the obligation tends to surface during a transaction rather than get assigned in advance.
Control also moves. When a building changes hands or a managing agent is replaced, the report should pass to whoever takes over. A new controller inheriting a building with no report and no record of when the last assessment happened has to start the cycle again.
What the Assessor Examines
An accredited air conditioning energy assessor works through the plant and the way it is run. A TM44 inspection normally covers:
- Refrigeration plant, its condition and its age against expected service life
- Air handling and distribution, including ductwork insulation and the state of grilles
- Controls, set points, time schedules and any building management system programming
- Sizing of the plant against the cooling load the building now carries
- Maintenance records, design documentation and metering data where these exist
Two assessment levels apply. The simpler level covers packaged and split systems. The higher level handles centralised plant, chillers and air handling units, and calls for a closer look at how the components interact.
What the Report Contains and Where It Goes
The report sets out what was found, how the system compares against what the building needs, and a list of recommendations for cutting energy use. It carries a reference number and is lodged on the register, which lets an enforcement officer check whether a building holds a valid one.
Validity runs from the inspection itself rather than from the lodgement, so a report produced late in a cycle does not buy back time already lost. Anyone taking on a building can check the register against the address before completing, which is why the document appears on due diligence lists more often than it once did.
Recommendations are advisory. Nothing in the regulations forces a controller to act on them. The report is the compliance evidence, and acting on the contents is a separate commercial decision.
What a TM44 Inspection Is Not
It is not servicing. The assessor observes and records, then leaves. No filters get changed and no coils get cleaned during the visit.
It is not an Energy Performance Certificate either. An EPC rates a whole building on carbon dioxide emissions. A TM44 report looks only at the cooling systems and at how they are operated. Both sit on the register, as separate documents with separate reference numbers.
Why Oversized Plant Keeps Turning Up
Sizing is the finding that surfaces most often. Cooling loads in commercial buildings have fallen a long way. Lighting draws a fraction of what it once did, IT equipment runs cooler than the kit it replaced, and glazing and insulation improve with every refurbishment cycle.
Plant specified for the building as it was rarely gets downsized when the load drops. Oversized systems short cycle, run away from their design point and cost more to operate than a correctly matched system would. The report will say so, though the remedy normally waits for the next plant replacement.
Making the Report Earn Its Keep
Filed and forgotten is the usual fate. A more useful approach treats the recommendations as a shortlist for the next refurbishment budget, and books the assessment alongside planned maintenance so the assessor arrives while records are already to hand. Gaps in the documentation push an assessor towards cautious assumptions about how the plant performs, and cautious assumptions rarely flatter a building.
