TM44 air conditioning inspections
If your building has air conditioning with a combined cooling output of more than 12 kW, the law requires a periodic energy-efficiency inspection — a TM44 inspection — at least every five years, carried out by an accredited energy assessor. It’s easy to overlook, because several small units can add up to the threshold without any single one being large.
Where this applies
This is the position in England and Wales under the Energy Performance of Buildings Regulations; Scotland and Northern Ireland have their own equivalent regimes. (Verified June 2026 — confirm current thresholds and penalties.)
Who needs one
A TM44 inspection is a legal requirement for any building whose air conditioning has a combined effective cooling output of more than 12 kW. The crucial word is combined: it’s the total of all the systems in the building, so several units each under 12 kW still count if together they exceed it. As a rough guide, more than about four or five typical units — or air conditioning serving more than roughly 120 m² of floor space — is likely to take you over the line.
What the inspection involves, and how often
The inspection must be carried out by an accredited energy assessor, following the methodology in CIBSE’s Technical Memorandum 44 (which is where the name comes from). The assessor reviews the system’s efficiency, its size relative to the building’s actual cooling need, its controls and how well it’s maintained, then produces a report with recommendations to improve efficiency. The report is lodged on the government register, is valid for five years, and must be kept and produced if an enforcement authority asks.
The first inspection is due within five years of the system first being put into service, and then at least every five years after that. You don’t have to act on the recommendations — but you do have to have the inspection.
Whose responsibility, and the penalties
Responsibility sits with the person who controls the operation of the system — typically the building owner or manager, not a tenant who simply uses a thermostat (though a lease can assign it). Enforcement is by local authorities, and failing to hold a valid inspection can bring a fixed penalty (commonly cited at £300 per building), so it’s worth knowing where you stand. If you’re unsure whether your systems exceed 12 kW, an air conditioning company can total the cooling outputs from the units’ data plates and confirm.
Worth more than avoiding a fine: a TM44 inspection often pays for itself. The recommendations can flag oversized plant, poor controls or maintenance gaps that, once addressed, cut energy use and running costs. Treat it as a free efficiency audit you’re required to have anyway.
Know exactly what to ask for
Build a free, impartial plan for your space — the right system, the size each room needs, and what good kit looks like. We don't sell or fit units.