Unused or Decommissioned Air Conditioning and TM44 Compliance

Commercial buildings often contain air conditioning systems that are no longer used, partly disconnected, left behind by a previous tenant, switched off at the isolator, or waiting to be removed during a future refurbishment. On paper, this may sound simple: if the system is not being used, why would it need a TM44 inspection?

In practice, this is one of the most common grey areas in TM44 air conditioning inspections. A building owner, landlord, managing agent or tenant may believe the system is “dead”, but there may be no clear evidence that it has been properly decommissioned. The indoor units may still be fixed to the wall. The outdoor condensers may still be present. The system may still be connected to power. Old drawings may still show air conditioning installed. A previous tenant may have added units without updating the compliance file. In those situations, the risk is not always the physical use of the system. The risk is the absence of evidence.

This article explains when unused, disconnected or decommissioned air conditioning can still create TM44 compliance questions, what property managers should check, and when it is safer to arrange a compliance review before assuming no inspection is required.

Why Unused Air Conditioning Creates a TM44 Grey Area

TM44 requirements apply to qualifying air conditioning systems in commercial buildings where the combined effective rated cooling output is over 12kW. The important point is that the threshold is not always based on one single unit. Several smaller systems can combine to take the building over the threshold. This is why a property with multiple split systems, VRF systems, cassette units, wall-mounted units, server room cooling, meeting room AC or tenant-installed units may still need assessment even where some units appear inactive.

The problem with unused air conditioning is that many buildings do not have a clean record of what has been removed, what remains connected, what is operational, and what has only been switched off temporarily. A facilities manager may say, “Those units are not used anymore.” A tenant may say, “They were already here when we moved in.” A landlord may say, “The previous occupier installed them.” None of those statements automatically proves that the system is outside the scope of TM44 inspection requirements.

For compliance purposes, the question is more structured: is there an air conditioning system in the building, is it capable of operating or intended to provide cooling, is the total capacity over the threshold, and is there sufficient evidence to show the system has been removed, permanently isolated or no longer relevant?

If the answer is unclear, the building may still carry compliance risk.

Switched Off Does Not Always Mean Decommissioned

One of the biggest mistakes is treating “switched off” and “decommissioned” as the same thing. They are not.

A switched-off system may simply be off because the weather is cold, because the tenant does not currently need cooling, because energy bills are high, because a fault exists, or because the site is vacant. The equipment may still be physically installed, electrically connected and capable of being brought back into use. In that situation, the system may still be part of the building’s air conditioning provision.

A decommissioned system should be different. Proper decommissioning normally means there is a clear, permanent change to the equipment status. The system may have been removed, safely isolated, disconnected by a competent contractor, had refrigerant recovered where required, and recorded in maintenance or project documents. The key word is evidence.

From a compliance perspective, a property manager should not rely only on a verbal explanation. If the system is visible, listed on an old asset schedule, shown on previous maintenance records, or still appears connected, it may raise questions during a property transaction, compliance audit, facilities handover or enforcement review.

This is especially relevant for buildings with mixed responsibilities, such as multi-let offices, retail parks, serviced offices, business centres, industrial units and commercial properties where tenants have made alterations over time.

Common Situations Where Old AC Causes Confusion

Unused or decommissioned air conditioning usually becomes a problem in five practical scenarios.

The first is a vacant commercial property. The building may have old wall-mounted split systems or rooftop condensers that are no longer in use, but no one has checked whether they remain connected. A landlord may be marketing the building as vacant, but if the systems remain installed and capable of use, the TM44 position may still need to be clarified. We cover this wider issue in our guide to vacant commercial property TM44 inspections.

The second is a tenant handover. A previous tenant may have installed air conditioning for meeting rooms, server areas, treatment rooms, retail areas or staff spaces. When the tenant leaves, the equipment may remain in place. The incoming tenant may not know whether it belongs to them, the landlord or the previous occupier. This can create uncertainty over who is responsible for compliance. This is closely linked to our article on tenant-installed air conditioning and TM44 risk.

The third is refurbishment. A building may be undergoing fit-out, strip-out or phased refurbishment. Some units may be removed, some may be retained, and others may be temporarily isolated. During this period, compliance files often become messy. If a building changes layout, use or cooling arrangement, the TM44 position should be checked rather than assumed. We explain this further in our guide to TM44 risk after commercial refurbishment.

The fourth is legacy equipment. Older buildings often have AC units that are no longer maintained but still physically present. Nobody may know the model numbers, capacities or operational status. These are the types of systems that often cause problems when a buyer, surveyor, solicitor, managing agent or facilities auditor asks for proof of compliance.

The fifth is partial decommissioning. This is where some equipment has been removed but other related components remain. For example, indoor units may be removed but outdoor condensers remain on the roof. Or outdoor units may be disconnected, but indoor units and pipework remain visible. Partial decommissioning can make it difficult to prove whether the system is still part of the building’s cooling provision without a proper review.

The 12kW Threshold Still Matters

Many businesses misunderstand the 12kW rule. They assume that if each individual unit is small, the building is outside TM44. That is not always correct. The threshold is generally considered across the combined effective rated cooling output of the air conditioning systems serving the building or relevant control area.

This matters because unused systems can distort the picture. A building may have 9kW of currently used cooling and 8kW of old disconnected cooling still present. If the old system is truly decommissioned and evidenced, it may not form part of the active cooling provision. But if the status is unclear, a cautious compliance review may be needed before the owner concludes that the building is below the threshold.

Property managers should check model numbers, manufacturer data plates, old O&M manuals, maintenance records and commissioning certificates where available. If those details are missing, our TM44 kW checker can help start the process by estimating whether the installed cooling capacity may be over the threshold.

Where the information is incomplete, photographs of indoor units, outdoor units, serial plates, roof plant, wall controllers and electrical isolators can help an assessor form an initial view. However, a site inspection may still be needed where the equipment status is uncertain.

What Counts as Evidence That AC Is No Longer Relevant?

The strongest position is not simply saying “we do not use it.” The strongest position is being able to show why the air conditioning no longer forms part of the building’s active system.

Useful evidence may include contractor decommissioning records, refrigerant recovery documentation, photos showing removed equipment, updated asset schedules, maintenance records confirming the system is no longer in service, electrical isolation certificates, strip-out records, landlord consent documentation, or updated O&M files showing the current cooling systems only.

In some cases, a short compliance note from a competent contractor or assessor may be useful. This can confirm that the visible system has been removed, isolated or appears non-operational based on the available evidence. This is not the same as a full TM44 certificate, but it may help a property manager document the position where the building does not require a full inspection.

If the building does require a full inspection, then the outcome should be a lodged TM44 certificate and report. This gives a clearer compliance trail than informal internal notes or assumptions.

Why This Matters During Property Sales and Leasing

Unused air conditioning is often ignored until a commercial property transaction. During a sale, lease renewal, refinancing, acquisition, due diligence exercise or tenant handover, compliance documents are reviewed more closely. That is when old systems become a problem.

A buyer may ask whether the building has a valid TM44 report. A solicitor may ask for energy compliance documents. A surveyor may spot external condensers on the roof or elevation. A tenant may ask whether the air conditioning is usable. A managing agent may inherit a site and realise that the AC asset register does not match what is physically installed.

At that point, the owner may need to act quickly. If there is no valid report, no clear asset list and no decommissioning evidence, the safest route is often to arrange a TM44 review or inspection rather than delay the transaction.

We see this issue frequently where a landlord believes the building does not need a report because the tenant is not using the air conditioning. However, if the equipment is still present and the total installed capacity may exceed 12kW, the compliance position should be checked properly. This is similar to the risk covered in our article on TM44 inspections before selling or leasing commercial property.

Case Study: Vacant Office With Old Split Systems

A managing agent takes over a small vacant office building. The previous tenant has left. There are three wall-mounted split systems in different office areas and two outdoor condensers still mounted externally. The agent is told by the landlord that the units “have not been used for years.” There is no current AC maintenance contract, no asset schedule and no decommissioning paperwork.

At first, the agent assumes no TM44 inspection is needed because the property is vacant and the air conditioning is not being used. However, during marketing, a prospective tenant asks whether the cooling works and whether the building has current compliance documents. The agent checks the old files and finds a service invoice from several years earlier showing total installed cooling above 12kW.

In this scenario, the issue is not whether someone is pressing the controller every day. The issue is that the systems remain installed, the capacity may exceed the threshold, and there is no evidence that the equipment has been properly removed or permanently decommissioned. A compliance review is needed. If the systems are still capable of operation, a TM44 inspection may be required. If they are genuinely decommissioned, the agent should obtain evidence and update the compliance file.

The lesson is simple: vacant does not automatically mean exempt, and unused does not automatically mean irrelevant.

Case Study: Retail Unit With Tenant-Installed Cooling

A landlord owns a retail unit in a parade. The original base-build had no major cooling system. A previous tenant installed multiple split units for customer areas, storage space and staff rooms. When that tenant left, the units were not removed. The new tenant uses only one of them and ignores the rest.

Several years later, the landlord receives a compliance request from a managing agent reviewing the whole property portfolio. The landlord says the air conditioning is the tenant’s responsibility. The tenant says most of the units were already installed before occupation. The maintenance contractor only services one active unit and does not have records for the others.

This is a classic responsibility problem. There may be enough installed cooling capacity to trigger TM44, but nobody has a complete asset record. Even if only one system is being used, the remaining systems may still be present and potentially operational. Without clear evidence of removal or isolation, the landlord and tenant can end up arguing while the compliance risk remains unresolved.

The practical solution is to identify every indoor and outdoor unit, record the model data where possible, confirm which systems are operational, and establish whether the combined active cooling exceeds the TM44 threshold. Where the threshold is met, a TM44 report should be arranged and lodged correctly.

Case Study: Refurbished Building With Partial Strip-Out

A commercial building is refurbished floor by floor. The contractor removes some old indoor cassette units but leaves roof plant in place for later works. The building remains partly occupied during the refurbishment. Some areas are cooled by existing systems, while other areas are awaiting new equipment.

This creates a compliance risk because the building’s cooling arrangement changes during the works. The old records no longer match the site. The future design is not yet fully commissioned. The retained systems may still be above 12kW. If a compliance audit happens during this transitional period, the owner needs a credible explanation supported by evidence.

In this type of case, it is usually sensible to review the TM44 position before and after refurbishment. Where systems are still operational and above the threshold, inspection may still be required. Where systems have been fully removed or permanently isolated, the compliance file should show that clearly. Where new systems are installed, the owner should also understand when the first inspection obligation may arise. We cover this point in more detail in our guide to new air conditioning installations and TM44 inspections.

The Role of the TM44 Register

Where a building has previously had a TM44 inspection, there should usually be a record of the lodged report. However, older records, incomplete addresses, company name changes, landlord changes and building reconfigurations can make the position harder to trace.

If a property manager is unsure whether a building already has a valid report, checking the TM44 register position is a sensible first step. This can help confirm whether a previous inspection exists, whether it may have expired, and whether a new inspection may now be needed.

However, register checks do not solve every problem. If the building has changed, old systems have been removed, new systems have been added, or tenant-installed systems are present, the register may not reflect the current site condition. That is why a current compliance review can be more valuable than relying only on old paperwork.

Why Maintenance Records Are Not the Same as TM44 Compliance

Many building owners assume that if their air conditioning contractor services the system, they are covered. Maintenance is important, but it is not the same as TM44 compliance.

A maintenance visit may clean filters, check operation, inspect refrigerant issues, look at faults and keep the system running. A TM44 inspection is a statutory energy assessment of qualifying air conditioning systems. It considers system efficiency, control, sizing, operation, maintenance condition and improvement recommendations. The report must also be completed by an accredited assessor and lodged correctly where required.

This distinction matters when systems are unused or partly disconnected. A maintenance contractor may stop servicing old units because the tenant says they are not used. That does not automatically prove those units are outside the TM44 scope. Similarly, a PPM contract may list only active systems and omit old equipment still visible on site. We explain this issue further in our article on PPM contracts versus TM44 compliance.

For a clean compliance file, the maintenance records and TM44 records should not contradict each other. If the maintenance file says there are six systems but the TM44 report only appears to cover three, someone may need to explain the difference.

What Property Managers Should Check Before Deciding No TM44 Is Needed

Before deciding that unused air conditioning does not need a TM44 inspection, property managers should complete a basic evidence review.

Start by walking the site and identifying all visible indoor units, outdoor units, roof plant, wall controllers and local isolators. Check whether controllers power on, whether systems appear labelled, and whether there are signs of recent servicing. Do not rely only on tenant comments or old assumptions.

Next, check the paperwork. Look for O&M manuals, commissioning sheets, F-Gas records, maintenance reports, asset lists, previous TM44 reports, refurbishment records and contractor decommissioning notes. If you have a previous TM44 report, compare the listed systems against what is currently visible on site.

Then consider the total capacity. If the combined active or potentially active systems may exceed 12kW, the building should not be dismissed as low risk without further review. The TM44 checker can help identify whether a building may fall within the inspection requirement.

Finally, decide whether the evidence is strong enough. If equipment has genuinely been removed, isolated and documented, the position may be straightforward. If the equipment remains installed and the paperwork is incomplete, it is usually safer to ask for a professional review.

Who Is Responsible When the System Is Old or Unused?

Responsibility depends on the lease, building control arrangements, plant ownership, service charge structure and who controls the air conditioning system. In simple owner-occupied buildings, the owner or occupier usually has direct control of the compliance position. In multi-let buildings, responsibility can be more complex.

Where a landlord controls central plant, the landlord or managing agent will normally manage compliance. Where a tenant has installed and controls its own air conditioning, the tenant may carry responsibility. Where equipment is historic, abandoned or left behind, the issue becomes more difficult. The building owner may still need to prove what is installed and whether it affects the building’s compliance position.

This is why responsibility should not be left vague. If a tenant installs, modifies, disconnects or removes AC equipment, the compliance file should be updated. If a landlord permits tenant alterations, the lease and licence documentation should make clear who is responsible for statutory compliance. Our TM44 responsibility guide explains these landlord, tenant and managing agent issues in more detail.

Why Photos Alone Are Useful but Not Always Enough

Photos are useful for initial screening. Clear photos of indoor units, outdoor condensers, model plates, electrical isolators and controllers can help identify likely system capacity and condition. For simple sites, photos may be enough to advise whether a full inspection is likely to be required.

However, photos do not always prove whether a system is operational, isolated, connected or decommissioned. A condenser may look old but still work. A wall unit may look abandoned but still be connected. A controller may be missing but the system may still form part of a wider VRF network. Conversely, equipment may appear present but may have been fully disconnected behind the scenes.

That is why the best approach combines photos with documents. Photos show what is physically present. Documents show what has been done. A site visit confirms the current condition where the risk cannot be resolved remotely.

Commercial Risks of Getting This Wrong

The direct risk is that a qualifying building may not have a valid TM44 inspection report. But the wider commercial risks can be more disruptive.

A missing or unclear TM44 position can delay lease negotiations, create friction during due diligence, cause questions from buyers, complicate service charge discussions, expose gaps in facilities management records, or create problems during internal compliance audits. In regulated or corporate environments, missing compliance evidence can also make the property team look disorganised.

There is also a reputational issue. When a client, tenant, buyer, auditor or senior manager asks for the TM44 compliance file, a vague answer such as “we think those units are not used” is weak. A better answer is: “The systems were reviewed, the active capacity was confirmed, the redundant equipment was documented, and the TM44 position is clear.”

That is the standard commercial property teams should aim for.

How TM44.uk Can Help

TM44.uk can help landlords, tenants, facilities managers and managing agents clarify the position before the issue becomes urgent. If your building has old, disconnected, unused or partly decommissioned air conditioning, we can review the available information and advise whether a full inspection is likely to be required.

For a quick initial review, send photographs of the indoor units, outdoor units, controller panels, model plates and any maintenance or decommissioning records you hold. Where the position is clear, we can advise the next step. Where the building appears to fall within the requirement, we can arrange a full TM44 inspection and produce the required lodged report.

For buildings with missing records, no asset list or uncertain cooling capacity, our team can help create a practical route forward. This may include a site survey, capacity review, register check, inspection booking and report delivery. If your issue is wider than one building, our TM44 portfolio management service can help review multiple sites and prioritise the highest-risk properties first.

You can also request a quote directly through our TM44 inspection quote form. The more information you provide at the start, the faster we can confirm the likely requirement and arrange the correct service.

Final Thoughts

Unused, disconnected or decommissioned air conditioning should not be ignored. In many commercial buildings, old AC equipment remains physically installed long after the original tenant, fit-out or maintenance arrangement has changed. If the system status is not clearly documented, it can still create TM44 compliance uncertainty.

The safest position is evidence-led. If the equipment has been properly removed or permanently decommissioned, keep the records. If the equipment remains installed and the total cooling capacity may exceed 12kW, check the TM44 position before assuming no inspection is needed. If old systems, missing asset lists or tenant-installed units make the situation unclear, get a professional review.

A clear TM44 compliance file protects the landlord, helps the managing agent, supports the tenant, and reduces avoidable problems during audits, transactions and handovers. For commercial buildings with unused or decommissioned AC, the question is not simply whether someone currently uses the cooling. The better question is whether you can prove the system is outside scope.

If you cannot prove it, it is worth checking before it becomes a problem.