TM44 Changes 2026: What the Coming ACIR Reforms Mean for UK Building Owners

For years, many businesses have treated a TM44 inspection as a document that needs to exist rather than a management tool that should be used. The report is commissioned, lodged and placed in a compliance folder, often without its recommendations reaching the person responsible for energy budgets, planned maintenance or future air-conditioning investment.

The Government now wants to address that problem.

Proposals published as part of the wider reform of the Energy Performance of Buildings regime would change the way Air Conditioning Inspection Reports, commonly called ACIRs or TM44 reports, communicate risk, efficiency and potential savings. The direction is clear: improve compliance, make reports easier to understand and give building operators stronger reasons to act on the findings.

However, an essential distinction must be made at the outset. At the time of writing, the proposed changes have not replaced the existing TM44 rules. The Government published a partial response to the Energy Performance of Buildings consultation in March 2026 and confirmed that a further response covering ACIRs would be published during 2026. Until new regulations are approved and brought into force, the current legal requirements continue to apply.

That means businesses should not wait for reform before checking their position. If your air-conditioning system has a combined effective rated output of more than 12 kW, it must still be inspected by an accredited air-conditioning energy assessor at intervals of no more than five years.

This guide explains what is legally required now, what the Government has proposed, what may change next and how landlords, facilities managers, occupiers and commercial property owners can prepare without wasting time or money.

What is an ACIR, and is it different from a TM44 report?

In everyday property and facilities-management language, the terms “TM44 inspection”, “TM44 report” and “air-conditioning inspection report” are often used interchangeably.

TM44 is the technical inspection methodology associated with the Chartered Institution of Building Services Engineers. ACIR is the regulatory name commonly used for the report produced following the inspection. For a building owner or manager, the practical outcome is a lodged report that records the system, assesses aspects of its energy efficiency and provides recommendations for improvement.

An ACIR is not the same as an air-conditioning maintenance record, an F-Gas leak-check certificate or a commercial EPC. These documents can support each other, but one does not automatically replace another. Our guide to TM44 inspections compared with F-Gas requirements explains this distinction in more detail.

A valid report produced after 6 April 2012 must be completed by an accredited assessor and lodged on the official Energy Performance of Buildings Register. A PDF supplied by a maintenance contractor is not automatically a valid ACIR simply because it contains “TM44” in the title. Businesses can use our TM44 Register guidance to understand how lodged records are checked.

The current TM44 rules in 2026

The foundation of the current regime remains straightforward: air-conditioning systems with an effective rated output of more than 12 kW must be inspected at intervals not exceeding five years.

The threshold is not limited to one large chiller or one individual outdoor unit. Several smaller units can form a system that exceeds 12 kW when their outputs are combined. Government guidance states that one or more air-conditioning units within a building controlled by a single person are considered a single system for the purposes of the regulations.

This is why a small office, dental practice, retail unit or restaurant can fall within scope even when no individual unit is rated above 12 kW. Four 3.5 kW units, for example, may create a combined capacity of 14 kW under common control. Our dedicated 12 kW TM44 threshold guide explains how to approach these calculations when the asset information is incomplete.

The person who controls the technical operation of the system is responsible for ensuring that the inspection is completed. In many buildings that person will be the owner or building manager. In a full repairing and insuring lease, control may sit with the occupier. Where a tenant installs and controls its own equipment, responsibility for that equipment can lie with the tenant. Contracting day-to-day maintenance to an FM provider does not necessarily remove the owner’s or occupier’s parallel duty.

If responsibility has recently transferred and the new controller was not given a valid report, the system must be inspected within three months. This is particularly relevant during acquisitions, lease changes, property-management handovers and corporate restructures. Our explanation of the TM44 three-month rule covers the handover risk in depth.

The report must be retained and transferred to anyone who subsequently takes over responsibility for the system. If Trading Standards requests it, the responsible person must provide it within seven days.

As of 28 August 2026, official guidance states that the penalty for failing to have a required ACIR is currently £300. A further £200 penalty can be issued for failing to provide a valid report within seven days of a request. These are the current published figures. The widely discussed £800 figure is a reform proposal, not yet the existing statutory penalty.

Why is the Government reviewing TM44 reports?

The proposed reform is not simply about changing the appearance of a certificate. It responds to two connected weaknesses in the current system: low compliance and limited action after an inspection.

The Government’s consultation states that compliance with ACIR requirements is believed to be very low. That means a significant number of qualifying systems may have no current lodged report at all. It also means the potential savings identified through inspections are not being realised across much of the building stock.

The second problem concerns usability. Existing reports can be long, technically dense and repetitive. A technically correct report has limited operational value if its most important conclusions are buried in dozens of pages or never reach the budget holder.

Think about a typical multi-floor office building. The facilities manager may understand the plant and controls, but capital expenditure is approved by a finance director or asset manager. A recommendation described only in technical language may remain untouched. The same recommendation expressed as a defined operational problem, a practical action and a credible range of potential savings has a far better chance of becoming an approved project.

That is the commercial logic behind the proposed redesign: make the findings more relevant to the people who decide what happens next.

The proposed £800 penalty: what has and has not changed

One of the most prominent proposals is to increase the penalty for failing to have a required ACIR from £300 to £800.

The consultation’s reasoning is direct. It concluded that the existing penalty may not be a sufficient deterrent when the cost of compliance can be higher than the fine. The proposed £800 figure was based on the consultation’s model of inspection costs and was intended to create a stronger financial incentive to comply.

The Government also proposed retaining the separate £200 penalty for failing to provide a valid report within seven days when requested by a Trading Standards Officer.

This proposal should be taken seriously, but it must not be reported as though it is already in force. The Government’s March 2026 publication was only a partial response. It said that the remaining response covering ACIRs would follow during 2026, subject to the wider regulatory process and parliamentary approval where required.

For building operators, the sensible position is therefore neither panic nor delay. The current duty already exists. A qualifying system that is overdue is non-compliant under today’s rules, regardless of whether the proposed £800 figure is eventually adopted, changed or postponed.

There is also a wider commercial risk. During a sale, letting, refinancing exercise or compliance audit, professional advisers may request the valid lodged report. Missing documentation can cause avoidable questions, slow a transaction and signal weak control of the building’s statutory records. Our guide to TM44 risk during commercial property transactions explains why the real cost can extend beyond the face value of a penalty.

How a redesigned ACIR could become more useful

The consultation proposes a report structure that places greater emphasis on useful conclusions rather than repetition. The suggested content includes the likely efficiency of the system, identified faults and actions, maintenance adequacy, controls and settings, system sizing in relation to cooling load, the ability to optimise performance under typical operating conditions, and a summary of key recommendations.

Most of those subjects already form part of a competent inspection. The important potential change is how clearly they are organised and communicated.

An effective future report should make it easier to answer four management questions:

1. What is the significant problem?

2. Why does it matter operationally or financially?

3. What action should be considered?

4. Which actions deserve priority?

That does not turn a TM44 inspection into a full investment-grade energy audit, detailed system design or maintenance visit. The inspection remains a structured assessment of air-conditioning energy efficiency. It does, however, create an opportunity to make the report more actionable.

For example, an assessor might identify that cooling and heating are operating simultaneously in the same zone. The useful management message is not merely that the controls are imperfect. It is that energy may be purchased twice to create opposing effects, and that reviewing setpoints, time schedules, dead bands and control logic could provide a relatively low-cost improvement.

Similarly, a system may have been sized for a former high-occupancy use but now serves a partially occupied or hybrid-working office. The equipment may remain functional while being poorly matched to the actual load. That observation could inform recommissioning, zoning changes or the replacement strategy when the plant reaches the end of its life.

This is why we advise businesses to treat their TM44 report recommendations as an evidence-based starting point for action, not as a simple pass-or-fail list.

The proposed cost metric could change the conversation

The most commercially interesting proposal is the possible inclusion of a cost metric within the ACIR methodology.

The idea is to show the potential financial value of specific recommendations by combining information about the air-conditioning system’s output, energy prices and the expected impact of improvements. If designed well, this could help move TM44 recommendations from the compliance file into maintenance planning and capital budgeting.

That is important because different decision-makers respond to different evidence. An energy manager may focus on kilowatt-hours and carbon. An FM team may focus on comfort complaints, system reliability and plant condition. A finance director may want expected annual savings, implementation cost and payback.

However, the Government has also acknowledged the difficulty. Commercial air-conditioning systems vary widely. Rated output is not the same as measured annual consumption. Buildings have different operating hours, occupancy patterns, control strategies, internal loads, tariffs and maintenance conditions. A standardised metric could become misleading if it creates false precision.

If cost information is introduced, it should therefore be interpreted as a decision-support estimate rather than a guaranteed saving. More detailed engineering analysis may still be required before a major investment such as replacing chillers, VRF systems or air-handling plant.

The existing consultation nevertheless provides a powerful indication of what policymakers want the regime to achieve. It refers to responses suggesting that implementing the full package of recommendations could typically produce energy savings of 30% to 40%, while lower-cost measures such as changing system schedules could deliver 10% to 20%. These figures come from consultation evidence and should not be treated as a promise for every building. They show why the Government sees stronger engagement with recommendations as worthwhile.

For owners deciding whether to repair, recommission or replace inefficient equipment, our guide to acting on an inefficient commercial air-conditioning system provides a practical framework.

Will existing TM44 reports become invalid?

Nothing in the current published position says that valid existing reports have automatically become invalid because reform is being considered.

The current requirement remains an inspection at intervals not exceeding five years. A report must be validly produced, lodged and retained. Unless future regulations introduce specific transitional provisions, businesses should continue to work from the inspection date and expiry position shown in their existing compliance records.

This is another reason to be careful with online headlines. “TM44 changes 2026” does not mean every business suddenly needs a new report in 2026. Equally, the possibility of future reform is not a reason to postpone an inspection that is already due.

If you cannot locate a report, first search the register and check the building address, report reference and inspection date. If no valid record exists, or the system has materially changed and its compliance position is unclear, seek advice from an accredited assessor. Our article on what to do when a TM44 certificate has expired explains the immediate steps for overdue properties.

What building owners should do before the reforms arrive

Good preparation is not about guessing the final legislation. It is about improving the quality of the information you already need to manage the system.

Start with the asset register. It should identify the indoor and outdoor equipment, manufacturer, model, location, rated cooling output, approximate installation date and the system or zone served. Where units have been removed, replaced or decommissioned, record that change clearly rather than leaving obsolete equipment on the list.

Next, locate the most recent lodged ACIR and confirm its inspection date. Do not rely solely on a document saved under a familiar filename. Check that it contains a valid report reference number and corresponds with the correct property and systems.

Maintenance information should then be brought together. Useful evidence may include planned preventive maintenance records, commissioning information, control schedules, F-Gas records, BMS trend data, fault history and details of significant alterations. Better documentation helps the assessor understand the installation and can make the inspection more efficient and valuable.

Finally, identify who controls each system. This is particularly important in multi-let buildings, shopping centres, serviced offices and properties where occupiers have installed supplementary units. The landlord may control central plant while individual tenants control separate equipment. A clear responsibility map reduces the risk that everyone assumes somebody else arranged the inspection.

Businesses without a reliable equipment schedule can still move forward. Read our practical guidance on arranging a TM44 inspection without an asset list and provide whatever information is available, including photographs, floor areas, unit counts and maintenance contacts.

A practical example: the compliant report that still creates value

Consider a regional office containing two VRF systems, several wall-mounted split units in meeting rooms and supplementary cooling in an IT room. The total comfort-cooling capacity controlled by the occupier exceeds 12 kW, so the system falls within scope.

The business has a valid report, but the building has changed since the last inspection. Occupancy is lower, working hours are more flexible, one floor has been sublet and the IT load has increased. Maintenance continues, yet nobody has reviewed whether the old time schedules and control zones still reflect the way the space is used.

Waiting for the next legal deadline without reviewing these changes may preserve the appearance of compliance while missing operational savings. A better approach is to retain the current report, update the asset and responsibility information, review any recommendations that remain open and prepare accurate evidence for the next inspection.

Under a more action-focused ACIR format, the same building could receive clearer prioritisation: low-cost control changes first, investigation of simultaneous heating and cooling second, and longer-term plant replacement planning linked to condition and refrigerant strategy. The inspection becomes more than a document. It becomes a structured checkpoint in the building’s energy and asset-management cycle.

Why waiting is the wrong strategy

Some owners may be tempted to delay commissioning an overdue inspection until the final reforms are announced. That approach creates risk without providing a clear benefit.

The current statutory duty has not been suspended. A valid report produced now addresses today’s compliance requirement and gives the business a current record of its system. If future regulations change report formats or enforcement arrangements, official transitional guidance should explain how existing records are treated.

Delay can also make the practical work harder. Asset information disappears when contractors change, staff leave and refurbishment records are not transferred. Roof access may need to be arranged. Tenants may need notice. Plant areas may be controlled by different parties. Starting before a deadline allows these issues to be resolved properly instead of turning the inspection into an emergency exercise.

For businesses ready to proceed, our guide explains what information is needed for a TM44 quotation, including the address, approximate number of systems, available capacity information, property type and access considerations.

How TM44.uk can help

TM44.uk provides nationwide air-conditioning inspections for commercial, public-sector and larger residential properties across the United Kingdom. We support single buildings, complex sites and multi-property portfolios through accredited air-conditioning energy assessors.

Our service can include reviewing the information supplied, confirming the likely inspection scope, arranging the site assessment, producing the report and completing statutory lodgement where applicable. We work with offices, hotels, schools, healthcare premises, retail properties, warehouses, industrial sites, restaurants, leisure facilities and managing agents responsible for mixed portfolios.

If you are unsure whether the combined capacity exceeds 12 kW, cannot find the previous report or have inherited a building with incomplete records, we can review the available information before confirming the next step. The objective is to give you a clear route to compliance rather than make the process more complicated.

You can request a nationwide TM44 quotation or speak to our team through the TM44.uk contact page. Where possible, send an asset list, maintenance schedule or photographs of the unit labels. If these are unavailable, provide the property address, type of building, approximate floor area and estimated number of air-conditioning units.

The direction of travel is already clear

The final detail of the ACIR reforms remains subject to the Government’s outstanding response and the regulatory process. It would be premature to present the £800 penalty, redesigned report or cost metric as settled law.

But the policy direction is difficult to miss. The Government wants higher compliance, clearer reports, stronger engagement with recommendations and better evidence of the savings that air-conditioning improvements could produce.

For responsible building owners, this should not be viewed only as a future enforcement story. It is an opportunity to bring compliance, maintenance and energy management into the same conversation.

A valid TM44 report proves that the required inspection has been completed and lodged. A well-prepared inspection can do more: it can reveal poor control, weak documentation, mismatched operating schedules, neglected maintenance and plant that no longer suits the building it serves.

The businesses best prepared for reform will not be those waiting for a new penalty figure. They will be the ones that already know which systems they control, when their reports expire, where their evidence is stored and which recommendations offer the strongest operational return.

If your report is missing, expired or approaching its five-year deadline, book your TM44 inspection with TM44.uk and put the compliance position in order before it becomes urgent.

This article provides general information and reflects the official position available on 28 August 2026. It is not legal advice. Proposed reforms may change before regulations are finalised or brought into force.

Official sources

• GOV.UK: A guide to air-conditioning inspections in buildings

• GOV.UK: Reforms to the Energy Performance of Buildings regime

• GOV.UK: Partial government response to the Energy Performance of Buildings reforms