In England and Wales, an air conditioning system with an effective rated output of more than 12 kW must generally be inspected by an accredited air conditioning energy assessor at intervals not exceeding five years. Where the same person controls more than one individual unit in a building, those units are treated as components of one system for this purpose. The person who controls the system's operation is responsible for ensuring the inspection takes place and keeping the report. The current GOV.UK guidance and the Energy Performance of Buildings Regulations should be used to determine the exact duty.
Understand what the 12 kW threshold measures
The threshold concerns the effective rated output of the air conditioning system, not simply the rating of one outdoor unit or the building's electrical demand. Where the relevant person controls more than one individual unit in a building, the regulations treat those units as components of one system, so several smaller units can bring that system within scope.
The official guidance explains how systems should be considered and includes both packaged and centralised arrangements. Portfolio owners should maintain an equipment schedule rather than relying on memory or model numbers visible from the floor. An accredited assessor can help resolve uncertain grouping or capacity information.
- List every relevant indoor and outdoor system.
- Record rated cooling output from reliable equipment information.
- Note additions, removals and replacements.
- Do not confuse input power with cooling output.
Identify the person who controls operation
Under the regulations, responsibility rests with the person who controls the operation of the system. This may be an owner or tenant depending on the building and contractual arrangements. Paying an energy bill or appointing a maintenance contractor does not by itself settle control in every case.
Where responsibilities are divided, the parties should document who arranges access, appoints the assessor, holds reports and implements operational decisions. Legal advice may be appropriate if the lease or management structure is unclear.
Arrange an accredited inspection and report
Inspections must be performed by an accredited air conditioning energy assessor. The assessor reviews system efficiency, sizing and operation and provides recommendations for improvement. The inspection is not a refrigerant leak check, electrical safety test or full maintenance visit, although evidence from those activities may assist.
The interval must not exceed five years, with timing rules for newly installed or changed systems set out in official guidance. Reports must be lodged on the relevant register. Owners and occupiers should verify the assessor's accreditation and retain the report so it can be produced when required.
Use the findings rather than filing them away
Recommendations can identify poor controls, simultaneous heating and cooling, excessive operating hours, blocked heat exchangers or systems that no longer match the occupied space. The report is advisory in important respects, but it can support a prioritised energy and maintenance plan.
Failure to hold a valid report can lead to enforcement and financial penalties under the applicable regime. Requirements and penalty details should be confirmed from current official guidance. A change of owner, tenant or managing agent should trigger a records check well before the next deadline.
Frequently asked questions
Is TM44 required when every individual unit is below 12 kW?
It can be. Where the same person controls multiple individual units in a building, the regulations treat them as components of one system, so their effective rated outputs may collectively exceed 12 kW.
Is a maintenance certificate the same as a TM44 inspection report?
No. Maintenance and F-gas work serve different purposes. The statutory energy inspection must be completed by an accredited air conditioning energy assessor and lodged on the relevant register.
How often is an inspection required?
The maximum interval is generally five years. Check the official timing rules for new installations, existing systems and material changes.
Must every recommendation be implemented?
The inspection report primarily provides energy-efficiency advice, but separate legal, safety or contractual duties may still require action. Evaluate recommendations with competent advisers and document decisions.
Related guides
Sources and further reading
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.