TM44 Air Conditioning Inspections Explained

In England and Wales the duty comes from Part 4 of the Energy Performance of Buildings (England and Wales) Regulations 2012, which applies to "air-conditioning systems with an effective rated output of more than 12kW" (regulation 17(1)). Note the wording: more than 12kW, so a system rated at exactly 12kW is outside the England and Wales regime.

The part most often misread is how units are added together. Regulation 17(2) does not ask whether units share a refrigerant circuit, a manufacturer or a control panel. It says that where the relevant person "has the power to control the temperature of more than one individual air-conditioning unit in a building", each unit is treated as a component of a single system. The test is the extent of one person's control over the building, not how the plant is plumbed. Ten unconnected 2kW split units in one office, all under the control of the same facilities manager, are a single 20kW system and in scope — a conclusion the government's own guidance states directly, confirming that scope "will include systems consisting of individual units which are less than 12kW, but whose combined effective rated output is more than 12kW".

Effective rated output has a defined meaning, and it is not the figure most people reach for. Regulation 17(3) defines it as "the maximum calorific output specified and guaranteed by the manufacturer of the system as being deliverable during continuous operation while complying with the useful efficiency indicated by the manufacturer" — a manufacturer's rating, not a measured duty, an electrical load, or a figure worked back from the building's cooling demand.

One further limit is easy to miss: since 2015 the duty in regulation 18(1) has applied to the "accessible parts" of the system. An assessor is not required to open up sealed plant or gain access to units that cannot reasonably be reached. That narrows the inspection, but it does not narrow the scope — an inaccessible unit still counts towards the 12kW threshold.

Regulation 18(1) requires inspection "at regular intervals not exceeding five years". There is no grace period built into that wording: the interval is a maximum, so a report that has passed its fifth anniversary is a breach from that day, not from the day someone notices.

For a new system, regulation 18(3)(a) sets the first deadline at the end of five years beginning with the date the system was "first put into service" — commissioning, not purchase, installation or practical completion. Systems already in service before 2008 had fixed backstop dates that have long passed: 4 January 2009 for systems over 250kW, and 4 January 2011 for systems over 12kW.

The provision that catches people out is regulation 21. Where the relevant person changes and the new relevant person is not given an inspection report, they must ensure the system is inspected within three months of becoming the relevant person. Not five years — three months. This bites on every change of managing agent, every acquisition, and every in-sourcing of an FM contract where the previous holder's paperwork does not come across. The companion duty in regulation 20 is what prevents it: the relevant person must keep the most recent inspection report, and on a change must give it to the incoming relevant person. A report that is handed over resets nothing and costs nothing; a report that is lost triggers a three-month clock and a fresh fee.

The output is a written report, given to the relevant person as soon as practicable after the inspection and lodged on the Energy Performance of Buildings Register, from which it takes the reference number that makes it valid. Reports produced on or after 6 April 2012 must carry that reference number, and only reports produced and lodged by accredited energy assessors count. Data entered on the register is kept there for at least twenty years.

Regulation 19(3) prescribes six items the report must contain, which is why the same headings appear whoever the assessor is: the register reference number, the address of the building, the assessor's name, the name and address of the assessor's employer or trading name, the date of the inspection, and the name of the accreditation scheme the assessor belongs to.

The part that earns the fee is the recommendations, where each finding is paired with an action — clean fouled coils, correct a setpoint, replace a failed sensor, install sub-metering, consider replacing an oversized or obsolete unit. A good report also lists the documentation the assessor could not find, which is a useful audit of the O&M records in its own right. Like an EPC, the value is in acting on the findings; the report itself changes nothing.

The three regimes are usually described as parallel. They are not, and the differences are substantive enough to matter to anyone running an estate across borders. The government's own guidance for England and Wales says plainly that buildings in Northern Ireland and Scotland "are subject to separate regulatory requirements and are not covered by or referred to in this guidance".

Northern Ireland is the close match. The Energy Performance of Buildings (Certificates and Inspections) Regulations (Northern Ireland) 2008 apply to systems with an effective rated output of more than 12 kW (regulation 14(1)), use the same aggregation test based on the relevant person's power to control the temperature of more than one unit (regulation 14(2)), require inspection of accessible parts at intervals not exceeding five years (regulation 15(1)), and impose the same three-month duty on an incoming relevant person who is not given the most recent report (regulation 18). The penalty for breaching those duties is also £300 (regulation 35(1)(d)).

Scotland is the outlier, and reaches the same destination by a different road. The duty is not in Scotland's Energy Performance of Buildings Regulations at all — those cover certificates only. It sits in regulation 17 of the Building (Scotland) Regulations 2004, as a continuing requirement on the owners of buildings under section 2 of the Building (Scotland) Act 2003. Four differences follow. The duty is on the owner, not on whoever controls the operation of the system. The exemption is for systems with a total effective output rating of "less than 12 kW", so a system at exactly 12 kW is in scope in Scotland and out of scope in England and Wales. Systems used solely for processes within a building — the classic case being dedicated IT and server-room cooling — are expressly excluded in Scotland, an exclusion that has no counterpart in the England and Wales regulations. And enforcement runs through the building standards system rather than through trading standards penalty charge notices.

What is common across all three is the five-year maximum interval, the coverage of accessible parts, and the reliance on CIBSE TM44 as the underlying inspection methodology.

One element of the cost is fixed in law and can be stated precisely: the fee for entering the data from which an inspection report is produced onto the register is £1.70, set by regulation 28(b) of the 2012 Regulations and last changed on 1 April 2022. That is the register fee alone, and it is a rounding error in any quotation.

The assessor's fee is the real number, and we do not publish a range for it, because we could not verify one to the standard the rest of this page is held to. TM44 inspections are almost never procured as standalone public contracts — they are bundled into wider HVAC maintenance and compliance packages, so the published award data that would let us derive real prices does not isolate them. The price guides that do quote figures are not independent of one another and none is a primary source. An invented range on a compliance page is worse than no range, so there is none here.

What can be said usefully is what moves the number, because that follows from the regulations themselves. Assessors price by the number of accessible units they must physically inspect and how spread out they are, so a VRF network of forty indoor units across four floors costs several times a single packaged rooftop unit. Because the scope is set by aggregation across everything one person controls, the unit count — not the building's floor area or its cooling load — is the driver. Good asset records, drawings and accessible plant reduce time on site; missing data plates, locked risers and ceiling-void units that need a cherry picker or an out-of-hours visit increase it. For a portfolio, inspections are usually quoted per site and the five-year cycles aligned so that one renewal date covers the estate. Get three quotes on a scoped unit schedule rather than a floor area, and they will be comparable.