TM44 inspections are the standard way UK air conditioning systems are assessed for energy performance under the Energy Performance of Buildings regime. If you control an air conditioning system above the legal threshold, you must ensure it is inspected at least every five years and that the most recent report is kept and handed over when responsibility changes. This guide explains the rules in plain English, shows you how to confirm whether you are in scope (including the common “multiple small units” trap), and gives a practical checklist so your inspection is faster, cheaper and more useful. It is written for facilities managers, building owners, landlords and managing agents across Bristol and the South West, but the compliance principles apply across England and Wales.

What is a TM44 inspection, and what problem does it solve?

TM44 in one sentence

TM44 is a recognised inspection methodology for air conditioning systems that produces an air conditioning inspection report focused on energy efficiency, correct sizing and practical improvement recommendations. For background on the TM44 document itself, see CIBSE’s TM44 overview. In England and Wales, the legal duty sits under the Energy Performance of Buildings regulations and applies to systems above the effective rated output threshold.

What TM44 is not

TM44 is often confused with routine servicing, refrigerant leak checks, and energy certificates. A TM44 inspection does not replace planned maintenance, filter changes, coil cleaning, drainage checks or safe refrigerant handling. It is also not an EPC or DEC assessment, even though the report may be stored alongside wider building energy records.

Why TM44 matters beyond “tick-box” compliance

The value of a TM44 inspection is in the recommendations. A good report identifies where your system is oversized, poorly controlled, poorly maintained, or operating outside its intended design. That matters because air conditioning energy use is driven as much by controls, schedules and setpoints as it is by the equipment itself. Treat TM44 as a structured energy and risk review: it helps you plan sensible upgrades, justify maintenance spend, and reduce comfort complaints while staying compliant.

Do you need a TM44 inspection? A decision-led checklist

The legal trigger: more than 12 kW effective rated output

The duty applies to air conditioning systems with an effective rated output of more than 12 kW. The key points are (1) “effective rated output” is a manufacturer-stated rating, and (2) the threshold can be met by one large system or several smaller units under one person’s control.

Quick decision table

Question	How to check	If the answer is “yes”
Do you control the technical operation of the air conditioning system?	Look at who manages maintenance, call-outs, settings policies and access to plant, not who changes the room thermostat.	You are likely the “relevant person” and have the compliance duty.
Is the effective rated output more than 12 kW?	Use rating plates, O&M manuals, or manufacturer data. Aggregate multiple units if they are one system under your control.	Arrange a TM44 inspection and plan renewals at least every five years.
Have you had an inspection in the last five years?	Check your building log book, compliance folder, or the most recent lodged report reference.	If not, schedule an inspection and fix the record-keeping gap.
Has the responsibility for the system changed without a handover report?	Common after acquisitions, lease changes, or contractor handovers.	Plan an inspection quickly and rebuild your compliance pack.

If you want a broader overview of how inspections fit into the wider Energy Performance of Buildings framework, see Controlled Climate’s guide to air conditioning inspections under the Energy Performance of Buildings regulations.

What does “12 kW” actually mean in practice?

Effective rated output: the rating you should use

“Effective rated output” is not a guess based on floor area. It is the maximum output specified and guaranteed by the manufacturer for continuous operation while meeting the stated efficiency. In practice, you normally find it on the unit rating plate, in operating and maintenance documentation, or via the manufacturer’s technical literature.

Multiple units: when several small systems become one big obligation

A common compliance failure is treating each indoor unit as separate. If you control multiple individual units in a building, the regulations treat them as components of a single system for the purpose of the threshold. That is why sites with lots of small wall-mounted splits often end up in scope even when no single unit looks “large”.

Common system types and how the threshold is usually approached

Single split systems: check the rated output on the outdoor unit and the documentation for the matched indoor unit.
Multi-split systems: aggregate the rated outputs where multiple indoor units are connected and controlled as one system.
VRF/VRV systems: treat the network as one system; the plant rating and how it is controlled matter more than any single terminal unit.
Packaged rooftop or close control units: use the manufacturer’s effective rated output and confirm whether there are additional cooling systems under the same control.

For practical examples of what is in scope, the most direct reference is the UK Government guidance on air conditioning inspections in buildings.

Who is responsible, and when is a TM44 inspection due?

The “relevant person” is the one who controls the system.

Responsibility sits with the person who controls the technical functioning of the system. In many buildings, that is the owner or the party with responsibility for the building services. In full repairing and insuring leases, it may be the occupier if they control the system and its maintenance. The key test is control over operation and upkeep, not who can alter setpoints in a meeting room.

Inspection frequency and first inspection rules

Inspections must be carried out at regular intervals not exceeding five years. The first inspection deadline depends on when the system was put into service and (for older systems) the size band, so a compliance check should start with “when was this system first put into service?”. If you do not know, treat that as a risk and rebuild your system history from documentation and maintenance records.

Enforcement and penalties

In England and Wales, enforcement is carried out through penalty charge notices. Where key duties are breached (including the duty to have the system inspected and to keep or hand over the latest report), the penalty amount is £300.

Changes in responsibility: the three-month trap

Another common failure point is handover. If control of the system moves to a new relevant person and the inspection report is not passed over, the new relevant person must ensure an inspection is carried out within three months. That means acquisitions, new leases, and managing agent changes should trigger a compliance review as part of mobilisation.

What happens during a TM44 inspection?

What the assessor needs before arriving on site

The quality and accessibility of your documentation directly affect the effectiveness and cost of an inspection. A competent assessor will ask for a list of documents in advance and will expect key records to be available before the site visit. The better your information, the more time they can spend on meaningful operational advice rather than chasing missing details.

What is typically inspected

The inspection focuses on accessible parts of the system and how the system is operated. Expect the assessor to review the equipment type, how it is sized against the building’s cooling demand, the control strategy, and the condition and maintenance history. They will also look for obvious inefficiencies such as poor scheduling, inappropriate setpoints, and maintenance issues that reduce heat transfer.

What you should expect on the day

Walkthrough of areas served, with notes on occupancy patterns and comfort issues.
Review of plant locations, safe access, and any permits or escort requirements.
Checks of controls, sensors, schedules and evidence of commissioning settings.
Discussion of maintenance and fault history, including any recurring call-outs or complaints.
A clear explanation of what will be included in the report and what evidence is needed for recommendations.

What must the TM44 report include?

Core content required in the report

The inspection report must include an assessment of air conditioning efficiency and the sizing of the system compared to the cooling requirements of the building. It must also include advice on cost-effective improvements, replacement, and alternative solutions. In addition, the report must consider how the system can optimise performance under typical operating conditions.

How to interpret recommendations without wasting money

Not every recommendation has the same payback, risk reduction or operational impact. A practical way to use the report is to group actions into three buckets:

Operational and control changes: scheduling, setpoints, deadbands, zoning, and user permissions.
Maintenance and condition fixes: coils, filters, drainage, fan performance, refrigerant system integrity, and control calibration.
Capital improvements: upgrading controls, replacing inefficient plant, improving zoning, or redesigning areas with chronic comfort issues.

The report is most valuable when it is translated into a simple action plan with owners, dates and evidence. If you manage multiple sites, standardise that action plan format so it becomes easy to audit.

Authenticity and record keeping

Keep the most recent inspection report in a safe place and store it with maintenance and energy records, ideally in a building logbook. Reports produced after statutory lodgement requirements were introduced should be lodged on the register, which also helps with replacement if a report is lost.

How to prepare for TM44: a practical pre-inspection checklist

Build a simple system, “passport”

Even if your paperwork is messy, you can make an inspection smoother by creating a one-page summary for each system:

System type (split, multi-split, VRF/VRV, packaged, close control) and areas served.
Effective rated outputs and where the evidence is stored (rating plate photo, manual page, manufacturer datasheet).
Controller type and where schedules and setpoints are managed (local controller, central controller, BMS).
Known issues: comfort complaints, high running cost concerns, repeat faults, nuisance trips.
Site access constraints: roof access, plant room permits, out-of-hours requirements.

Gather the documents assessors actually use

Operating and maintenance manuals, commissioning records and as-fitted drawings (if available).
Controls documentation: setpoints, schedules, zoning, and any BMS trend data that demonstrates typical operation.
Maintenance records, service reports and planned maintenance schedules.
Evidence of repairs or major changes since the last inspection.

Align TM44 with routine maintenance to prevent “paper compliance”

TM44 works best when it sits on top of a structured servicing programme. If you need a baseline checklist for what “good” looks like, look for a service scope that covers filters, coils, refrigerant system checks and drainage inspection. See air conditioning service and maintenance in Bristol and the South West for an example of a detailed service checklist and how service frequency is typically set by usage.

After the report: turning compliance into measurable improvements

Start with low-disruption operational wins

Before spending on new equipment, most sites can improve performance through better operational discipline: tighten schedules to match occupancy, avoid overcooling, set clear policies for comfort requests, and review who has permission to override settings. Where a system is used for both heating and cooling, reduce the risk of simultaneous demand by reviewing zoning and control logic.

Fix “hidden” efficiency losses through maintenance.

Many TM44 reports highlight issues that are not glamorous but have a direct energy effect: dirty coils, blocked filters, poor drainage, incorrect refrigerant charge, failing fans, or drifting sensors. The quickest route to sustained improvement is to address these via planned maintenance, then re-check performance and comfort in normal operation.

Plan upgrades based on evidence, not fashion

If the report indicates oversizing, poor zoning, or outdated controls, upgrades can deliver both comfort and energy benefits when they are properly specified. For multi-zone commercial buildings, this often means reviewing system architecture, control integration and how different areas are scheduled. Where a redesign or upgrade is needed, start with a survey that captures usage patterns, heat gains, and constraints, then match solutions to real demand.

For organisations considering broader plant improvements or additions, use TM44 recommendations as inputs into your specification process. You can explore typical commercial solution categories on the commercial air conditioning installations page and then validate what fits your building through a site survey.

Common TM44 mistakes (and how to avoid them)

Mistake 1: Assuming “small units” means you are out of scope

Sites with multiple small splits are often in scope because outputs can be aggregated when the units are under one person’s control. If you have several indoor units across a floor, treat that as a prompt to confirm the total effective rated output rather than guessing.

Mistake 2: Confusing inspection with servicing

A TM44 inspection does not clean coils, replace filters or resolve faults. If servicing is neglected, the inspection will often identify maintenance-driven inefficiency, and you will end up paying for both the report and emergency call-outs. Put servicing first, then use TM44 to improve operation and planning.

Mistake 3: Losing reports and failing to hand them over

Keep the most recent report in your compliance folder and make it part of your handover checklist. When responsibility changes, confirm that the report is transferred and that the renewal date is in your compliance calendar. If you inherit a system with no report, treat it as an urgent compliance item.

Mistake 4: Treating recommendations as “optional, therefore ignorable”

You may not be forced to implement every recommendation, but ignoring them defeats the point of the inspection. Use the report to prioritise actions that improve comfort and stability, reduce energy waste, or reduce operational risk, then document what you did and why.

Next steps for Bristol and the South West

Build a simple TM44 compliance pack

A practical compliance pack for a site typically includes:

The latest TM44 inspection report and the next renewal date.
An equipment list with effective rated outputs and plant locations.
Maintenance records and service reports.
Evidence of actions taken against TM44 recommendations (even if staged).
A named owner for compliance and escalation routes for faults.

Get support with servicing, upgrades and evidence.

If you need help turning inspection findings into practical improvements, Controlled Climate supports commercial sites across Bristol and the South West with servicing, maintenance planning and upgrade work. Case studies can help you sense-check what is feasible in real buildings: see Controlled Climate case studies.

If you want to discuss a TM44-driven action plan, a maintenance programme, or a compliance-first upgrade survey, use the contact page or submit a request via the free survey request form.

Summary

TM44 inspections are a legal and practical requirement for air conditioning systems above the 12 kW effective rated output threshold. The duty sits with the party that controls the system and must be renewed at least every five years, with extra care needed during handovers. The best outcomes come when you prepare proper documentation, align inspections with planned maintenance, and convert recommendations into a tracked action plan. If you operate sites in Bristol or the South West, build a simple compliance pack now and schedule inspections before deadlines become urgent.

Frequently Asked Questions

Is the threshold “12 kW and above” or “more than 12 kW”?

The legislation and government guidance use “more than 12 kW”. In practice, many organisations treat 12 kW as the trigger and confirm outputs rather than relying on assumptions.

We have several small split systems. Do we need TM44?

Possibly. If the units are under one person’s control and the combined effective rated output is more than 12 kW, the site is in scope. Confirm via rating plates or documentation.

Does TM44 apply to process cooling?

The regulations are not restricted to comfort cooling only, and refrigeration for process applications can be inspected. Dedicated process cooling needs careful interpretation and specialist advice.

How often do we need to renew the inspection?

Inspections must be carried out at intervals not exceeding five years. Many organisations align this with planned maintenance reviews so the recommendations remain relevant.

What if we cannot find our last report?

Start by checking your building log book, compliance folder and maintenance records. The government guidance explains that reports are lodged on a register, which can help with replacement if details are available.

What should we do with the recommendations?

Convert them into an action list with owners and dates. Start with operational controls and maintenance issues, then scope capital works where evidence supports it.

Can a maintenance contractor help even if they did not perform the TM44 inspection?

Yes. Maintenance teams can implement many recommendations (cleaning, repairs, control calibration, and schedule changes) and can support upgrades where needed.

TM44 Air Conditioning Inspections: Who Needs One, What 12 kW Means, and How Often (UK, Bristol & South West)