TM44 air conditioning inspections explained

What TM44 is

TM44 is the name of the guidance used by energy assessors to inspect air conditioning systems in buildings. The legal duty comes from the Energy Performance of Buildings regulations. The government’s guide to air conditioning inspections says that all air conditioning systems with an effective rated output of more than 12kW must be regularly inspected by an energy assessor.

In practice, “TM44 inspection” is what building managers, landlords and agents call it.

The 12kW threshold

The 12kW figure refers to the effective rated output of the air conditioning in the building, and multiple systems can count together. A single wall unit in a small office will be well below it. A floor of ceiling cassettes on a multi zone system, or several split systems serving one building, can easily pass it.

Situation	Likely over 12kW?
One wall unit in a small studio	no
Two or three small splits in a shop	possibly, check the ratings
Open plan office floor with cassettes	often yes
Multi let office building with central plant	yes
Server room with dedicated units plus office cooling	often yes

If you are not sure, the rated outputs are on each unit’s data plate and in the installation paperwork. An energy assessor can confirm.

How often, and by whom

The inspection must be carried out at least every five years by an accredited air conditioning energy assessor. The report is lodged on the national register. Keep a copy with the building’s records: managing agents, buyers and tenants may ask for it.

What the inspector looks at

A TM44 inspection is about energy use and suitability, not cleaning. Typically the assessor will:

• review the system’s records, maintenance logs and any previous report
• look at the size of the system against the cooling load of the building
• check the condition and efficiency of the main components
• review controls, time settings and set points
• look at how the building is used and whether cooling is needed where it is supplied
• give advice on improvements, such as better controls, replacing old plant or reducing loads

The aim is to cut wasted energy. A common finding in London offices is cooling and heating running at the same time in different zones, or systems running overnight and at weekends when the building is empty.

How it fits with other duties

TM44 sits alongside two other things:

Duty	What it is	Frequency
TM44 inspection	energy and suitability inspection by an energy assessor	at least every 5 years for systems over 12kW
F-gas leak checks	legal checks for refrigerant leaks by a certified engineer	set by the charge size, for systems at or above 5 tonnes CO2 equivalent (gov.uk)
Servicing	cleaning and maintenance	usually at least yearly, as the manufacturer advises

Servicing and F-gas leak checks are carried out by an engineer with an F-gas qualification working for a certified company. TM44 is done by an energy assessor, who may or may not also be a refrigeration engineer.

Canary Wharf and other managed estates

Many offices at Canary Wharf, on the Isle of Dogs and across Tower Hamlets sit in large managed buildings where the landlord runs central plant and tenants add their own cooling for meeting rooms or comms rooms. In that set up:

• the landlord or estate usually holds the TM44 for the base building systems
• a tenant who installs its own systems may be responsible for those
• the lease and the building manager will set out who does what

If you are a tenant planning new cooling, ask the building manager whether your new units will be added to the building’s TM44 records or whether you need your own inspection. Our Canary Wharf area page covers the local set up, and our guide to office air conditioning and landlord consent explains the approvals.

Getting ready for an inspection

Before the assessor visits, gather:

• a list of all air conditioning units in the building, with makes, models and rated outputs
• installation and commissioning records
• maintenance and service records
• F-gas leak check records
• any previous TM44 report
• a plan showing which areas each system serves

Having these ready saves time on site and gives a more useful report.

Acting on the report

A TM44 report is advice rather than a list of compulsory works, but it often points to quick wins: setting timers correctly, stopping heating and cooling fighting each other, cleaning coils, or replacing very old, inefficient units. If replacement makes sense, plan it alongside your lease position and the landlord’s consent process. Our office air conditioning page explains how we survey and design commercial systems.