Business Energy Glossary
What is a TM44 air conditioning inspection?
TM44 is the UK technical methodology for inspection of air conditioning systems with an aggregate rated cooling output above 12 kW. Inspections are required every five years for commercial buildings and produce a report identifying improvements to system efficiency. TM44 is the methodology document (published by CIBSE); the regulatory requirement comes from the Energy Performance of Buildings Regulations. Inspections must be carried out by an accredited energy assessor and the report lodged on the central register.
TM44 inspections are a regular obligation for commercial building owners and operators with significant air conditioning. Understanding the requirement, the inspection scope, and the typical recommendations matters for compliance and for capital planning around HVAC equipment.
On this page
What TM44 requires
The TM44 inspection covers:
- The air conditioning system equipment (chillers, fan coil units, split systems, etc.).
- Controls, sensors, and BMS integration.
- Sizing relative to building requirements.
- Maintenance condition.
- Operating efficiency relative to benchmarks.
The inspector produces a report (lodged on the central register) identifying findings and improvement recommendations.
When inspections are needed
TM44 inspections are required:
- For air conditioning systems with aggregate rated output above 12 kW.
- At intervals of no more than five years.
- Within five years of installation for new systems.
- At the next due date when systems are extended or replaced.
The 12 kW threshold is the total rated output of all air conditioning equipment in the building, not individual units. A building with multiple smaller systems totalling above 12 kW is in scope.
What is inspected
The inspection scope includes:
- System inventory. Equipment type, capacity, age, refrigerant.
- Maintenance review. Records, condition, fault history.
- Controls assessment. Time and temperature settings, dead bands, zoning, occupant override.
- Building envelope and load. Insulation, glazing, solar gain affecting cooling load.
- Operational practices. Concurrent heating/cooling, ventilation strategy, weekend operation.
- Refrigerant inventory. Type, quantity, leak detection arrangements.
The inspector typically reviews documentation in advance and conducts a site visit to verify findings and identify opportunities.
Common recommendations
Typical TM44 report recommendations:
- Controls upgrade. Adding occupancy sensors, dead bands, zone controls.
- Set point review. Wider dead bands (e.g. 21-25°C instead of 22-23°C) to reduce concurrent heating/cooling.
- Maintenance improvement. Regular cleaning, filter replacement, refrigerant leak detection.
- Equipment replacement. End-of-life chillers with higher COP modern equivalents.
- Refrigerant replacement. Lower-GWP refrigerants (HFOs replacing HFCs).
- Solar gain reduction. Solar control glazing, internal blinds, external shading.
Recommendations are typically categorised by payback period and complexity. The building operator decides which to implement.
Penalties for non-compliance
Failure to commission a TM44 inspection on schedule attracts a £300 penalty. The penalty is per inspection due, so multi-year non-compliance can accumulate. Local authorities (Trading Standards) enforce.
Beyond the penalty, the operational benefits of acting on TM44 recommendations typically far exceed the inspection cost. Improvements identified in TM44 reports often deliver 10 to 30 per cent reductions in air conditioning energy use.
The inspection process
Typical inspection workflow:
- Engagement. Building operator engages an accredited energy assessor.
- Documentation review. Assessor reviews equipment lists, maintenance records, BMS data, building plans.
- Site visit. Assessor inspects equipment, controls, building envelope.
- Report drafting. Findings, benchmarks, recommendations compiled into the TM44 report.
- Central register lodgement. Report uploaded to the EPB Register.
- Building operator receives report. Implementation of recommendations is voluntary but typically valuable.
Typical inspection cost ranges from £500 for a small office to £3,000 for a complex multi-system building. Larger industrial buildings can cost more.
a TM44 air conditioning inspection FAQs
What is a TM44 inspection?
The UK methodology for inspection of air conditioning systems with aggregate rated cooling output above 12 kW. Inspections are required every five years and produce a report identifying improvements to system efficiency.
When does my building need a TM44 inspection?
If aggregate air conditioning rated output exceeds 12 kW. Inspections are required at intervals of no more than five years. New systems must be inspected within five years of installation.
What does the inspector check?
Equipment inventory, maintenance records, controls and set points, building envelope and load, operational practices, and refrigerant inventory. The inspector typically reviews documentation and conducts a site visit.
How much does a TM44 inspection cost?
Typically £500 for a small office to £3,000 for a complex multi-system building. Larger industrial buildings can cost more. Cost depends on system complexity, building size, and assessor location.
What happens if I do not have a TM44 inspection?
A £300 penalty per inspection due, enforced by Trading Standards. Penalties accumulate across multiple missed inspections. The operational benefits of acting on TM44 recommendations typically far exceed the inspection cost.
Do I have to implement TM44 recommendations?
No. Implementation is voluntary. However, recommendations typically deliver 10 to 30 per cent reductions in air conditioning energy use, often with short payback periods.
Who can carry out a TM44 inspection?
An accredited energy assessor with the appropriate qualification. Accreditation is via the major Accreditation Schemes (CIBSE Certification, Stroma, Elmhurst, and others).
What is the 12 kW threshold?
The aggregate rated cooling output of all air conditioning equipment in the building. A building with multiple smaller units totalling more than 12 kW is in scope, even if no individual unit exceeds the threshold.