TM44-style air-conditioning inspections are a legal duty in England and Wales for systems with an effective rated cooling output of more than 12 kW. The building owner or manager must have the system inspected by an accredited assessor. F-gas leak checks are a separate duty. Skipping either can mean a penalty, not just a wasted certificate.
The legal test is output, not the brand
In England and Wales, the Energy Performance of Buildings Regulations require air-conditioning inspections for systems with an effective rated output of more than 12 kW. TM44 is the CIBSE methodology assessors use to do that inspection. The certificate is sold under the TM44 name. The legal duty is the inspection, not the brand of the method.
Twelve kilowatts is not huge commercial plant. A couple of office cassettes or a modest VRF indoor set can clear it. Multi-splits serving one building are assessed on the system, not on each indoor head in isolation. If you are unsure, add up the cooling capacity on the outdoor nameplates and get an assessor to confirm. This page sits next to the longer TM44 inspections over 12 kW guide. Use that for the inspection process. Use this one for the legal yes or no. Scotland and Northern Ireland have their own energy-performance rules: do not paste an England answer onto a Glasgow building.
- Over 12 kW effective rated cooling output: inspection duty applies.
- First inspection within five years of the system entering service, then at least every five years.
- TM44 is not an F-gas leak check.
Who must commission it, and how often
The building owner or the person in control of the air-conditioning system commissions the inspection. Tenants sometimes hold the duty under the lease. Read the lease before you argue about the invoice. First inspection is due within five years of the system being put into service, then at least every five years. An earlier inspection can be required if the system changes.
The output is an inspection report with recommendations, not a pass-fail MOT that switches the plant off. You are not legally forced to carry out every recommendation the next morning. You are required to have a valid inspection in place. Keep the report with the F-gas logbook. They answer different questions. TM44 looks at efficiency, controls and siting. F-gas leak checking looks at refrigerant containment.
What the assessor actually looks at
Access to indoor and outdoor units, controls, maintenance records, and whether the system is fighting the building. Recommendations often include setpoints, filters, zoning, and replacing oversized or elderly plant. A well-maintained system still needs the certificate if it is over 12 kW.
If plant is inaccessible, the assessor will say so. That is a facilities problem, not a reason to skip the duty. Domestic houses with a single 3.5 kW split are normally under the threshold. A large house with multiple outdoor units can creep over it. Count capacity, do not assume home means exempt.
How this meets a quote or a sale
Buyers, lenders and facilities managers ask for the TM44 report on commercial stock. Produce it. If you have never had one, book it before exchange rather than during the other side's due diligence.
An inspection is not a maintenance contract. If the report says the coils are blocked, hire an F-gas engineer. We introduce installers and maintenance firms. Accredited TM44 assessors are a related but distinct booking. Use the quote form for plant work, and ask the assessor route separately if you only need the certificate.
Frequently asked questions
Is TM44 required for a house?
Only if the air-conditioning system's effective rated cooling output is more than 12 kW. A typical single-room split is under that. Several large outdoor units on one dwelling can exceed it.
Is TM44 the same as an F-gas leak check?
No. TM44 is an energy-performance inspection of the air-conditioning system. F-gas leak checks are a refrigerant legal duty based on charge and gas type. You may need both.
How often is TM44 due?
At least every five years, and within five years of the system first being put into service, unless an earlier inspection is required. Do not wait for a sale to discover it is overdue.
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How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.