TM44 for Industrial Estates and Multi-Unit Business Parks: AC Compliance Guide for UK Landlords and Managing Agents

Industrial estates, trading estates and multi-unit business parks are often treated as simple commercial property assets. A row of units, a few offices, some workshops, shared parking, maybe a reception block, and multiple tenants operating independently. On the surface, they may not look like the type of buildings that need a TM44 air conditioning inspection.

That assumption is where many landlords, managing agents and business park operators get caught out.

TM44 compliance is not only an issue for large office towers, hotels, shopping centres or corporate headquarters. Any non-domestic building with air conditioning systems where the combined effective rated cooling output exceeds 12kW may require a TM44 inspection. On industrial estates and multi-unit business parks, that threshold can be reached more easily than many property owners realise.

A small reception office, a tenant meeting room, a first-floor admin area, a server cupboard, a workshop office, and two or three split air conditioning systems across the site can quickly create a compliance responsibility. When several units sit under the same ownership, same landlord control, same managing agent, or shared building services arrangement, the position can become more complex.

This guide explains how TM44 applies to industrial estates and multi-unit business parks, who may be responsible, what evidence is normally needed, common compliance gaps, and how TM44.uk can help landlords, agents and occupiers stay compliant without unnecessary disruption.

What is a TM44 air conditioning inspection?

A TM44 inspection is a statutory air conditioning energy assessment for qualifying commercial buildings. It is designed to review the efficiency, operation, control and general condition of air conditioning systems. The inspection is non-intrusive, which means equipment is visually assessed and records are reviewed, but systems are not dismantled, refrigerant circuits are not opened, and electrical testing is not carried out.

The purpose is not simply to issue a certificate. A proper TM44 inspection helps identify where air conditioning may be wasting energy, operating inefficiently, oversized, poorly controlled, badly maintained or running when it does not need to.

For a full explanation of the legal position, you can read our detailed guide to TM44 inspection requirements in the UK. For property owners who want to understand the wider process, our page on TM44 air conditioning inspections explains what is included and how the inspection is arranged.

Why industrial estates and business parks are often missed

Industrial estates are one of the most overlooked property types for TM44 compliance. The main reason is simple: people associate TM44 with big cooling systems. They imagine central plant, chillers, large rooftop units or complex commercial HVAC systems. Many industrial units, however, use smaller split systems or multi-split air conditioning units fitted over time as tenants change, offices are refurbished, or new areas are created inside the building.

A unit may originally have been a basic warehouse or workshop. Over several years, the tenant adds:

• A first-floor office
• A reception area
• A staff welfare room
• A meeting room
• A small server or IT room
• A showroom space
• A quality-control office
• A customer-facing trade counter

Each area may have its own split system. One 5kW unit may not trigger TM44 by itself. Two or three units may. Across a business park, the picture becomes even more complicated because some air conditioning may be landlord-controlled, some tenant-installed, some inherited from previous occupiers, and some missing from the asset list altogether.

This is why industrial estates and multi-unit parks often have hidden TM44 exposure. The systems are not always large, but the combined cooling capacity can still cross the 12kW threshold.

If you are unsure whether your site reaches the threshold, our TM44 checker can help you make a first-stage compliance check before requesting a formal quote.

Does a multi-unit business park need one TM44 inspection or several?

There is no single answer that applies to every estate. It depends on how the buildings are arranged, how the air conditioning systems are controlled, who owns or occupies each unit, and whether the systems serve one building, several buildings, common parts or individual tenant spaces.

For example, a business park may include:

• Separate self-contained industrial units
• Shared office buildings
• Multi-let commercial blocks
• Warehouses with internal office pods
• Shared reception areas
• Landlord-controlled common areas
• Tenant-controlled air conditioning
• Outdoor condenser units serving different demises
• Roof-mounted systems serving several zones
• Systems added during fit-out works

In some cases, each unit may need to be considered separately. In other cases, a wider estate-level review may be needed to understand the combined air conditioning position. The key point is that the compliance question should not be answered by guesswork. It should be based on the installed equipment, rated cooling outputs, control arrangements and responsibility structure.

This is where many landlords and agents benefit from a practical pre-quote review. At TM44.uk, we normally ask for the property address, basic site description, number of units, visible AC asset information, any maintenance records, and details of who controls the equipment. If you do not have a full asset list, we can still advise on the next step. Our guide on what we need from you for a TM44 quote explains the information that helps us price and plan the inspection correctly.

Who is responsible for TM44 on an industrial estate?

Responsibility can depend on the lease, ownership structure, service charge arrangement and who controls the air conditioning system. In simple terms, the person or organisation that controls the operation of the air conditioning system is normally the party expected to ensure the inspection is completed.

On an industrial estate, this may be:

• The freeholder
• The commercial landlord
• The managing agent
• The tenant
• A facilities management company
• A property investment company
• A portfolio manager
• A site operator
• A head tenant with subtenants

The difficulty is that responsibility is not always clear in practice. A landlord may own the building, but the tenant may have installed the air conditioning. A tenant may use the system daily, but the landlord may control the roof space where condensers are located. A managing agent may handle statutory compliance, but not have a current asset list. A previous tenant may have added units without documentation.

For this reason, TM44 should be treated as part of the wider commercial property compliance file. It should sit alongside EPCs, F-Gas records, maintenance reports, lease documents, service charge records and asset registers. Our guide on TM44 legal responsibility between landlord, tenant and managing agent covers this area in more detail.

Common TM44 compliance risks on industrial estates

Industrial estates create several recurring TM44 risks. These are the issues we see most often when reviewing multi-unit commercial sites.

Missing or incomplete air conditioning asset lists

Many estates do not have a single up-to-date record of all installed air conditioning systems. Maintenance contractors may have partial records. Tenants may have separate invoices. Some units may have older wall-mounted or ceiling cassette systems with faded labels. Rooftop condensers may be difficult to match to indoor units.

Without an asset list, it becomes harder to confirm whether the combined output exceeds 12kW, which units need to be inspected, and who is responsible.

If this is your situation, read our guide on what happens when there is no asset list for a TM44 inspection. A missing asset list does not always stop the process, but it should be dealt with properly.

Tenant fit-outs changing the compliance position

A unit may not have required TM44 when first built. Later, a tenant may convert part of the warehouse into office space and add air conditioning. Another tenant may add a trade counter or showroom. A third may install cooling for staff comfort or IT equipment.

Over time, the site changes. The compliance position changes with it.

This is why commercial fit-outs, refurbishment works and tenant improvements should trigger a TM44 compliance review. If the site has recently changed, our article on TM44 risk after commercial refurbishment is relevant.

Assuming small split systems do not count

One of the biggest mistakes is assuming that TM44 only applies to large central systems. In reality, multiple smaller systems can count when their combined cooling output exceeds the relevant threshold. This is particularly important for multi-unit buildings, workshops with office areas, and estates where each tenant has one or two systems.

Our guide on checking the TM44 12kW threshold explains why the total installed capacity matters.

No one checks TM44 during lease events

Industrial units are frequently leased, assigned, surrendered, refurbished or reoccupied. During these moments, landlords and agents often focus on rent, dilapidations, EPCs, fire safety, asbestos records and service charge issues. TM44 is often missed.

That can cause problems later if the new tenant, solicitor, insurer, buyer or compliance auditor asks for evidence of air conditioning inspection. For lease-related risk, our guide on TM44 dilapidations and commercial lease AC compliance is worth linking from this article.

F-Gas records are confused with TM44 compliance

Many industrial estates have F-Gas records because air conditioning contractors carry out maintenance and refrigerant leak checks. These records are useful, but they are not the same as a TM44 inspection.

F-Gas focuses mainly on refrigerant leak prevention and regulatory control of fluorinated gases. TM44 focuses on energy performance, efficiency, sizing, controls, operation and recommendations. A site can have F-Gas records and still be missing a valid TM44 report.

For readers who need the difference explained, link naturally to your F-Gas leak testing and compliance checks service page.

What does a TM44 inspection include for a business park?

A TM44 inspection for an industrial estate or business park will usually involve a combination of site inspection, equipment review and document review. The exact scope depends on the number of buildings, number of systems, accessibility and available records.

A typical inspection may include:

• Visual inspection of accessible indoor and outdoor AC equipment
• Review of manufacturer, model and rated cooling capacity where visible
• Review of maintenance records, if available
• Review of F-Gas leak check records, if relevant
• Assessment of control settings and operation
• Identification of obvious poor practice or energy waste
• Review of zoning and system suitability
• Photographic evidence where permitted
• Notes on inaccessible areas or missing data
• Recommendations for improving energy efficiency
• Preparation of the TM44 report
• Lodgement where required

The inspection is non-intrusive. Assessors do not open refrigerant circuits, dismantle equipment, carry out repairs or perform electrical testing as part of the standard TM44 assessment.

Where access is limited, for example roof areas, ceiling voids, tenant-controlled rooms or locked plant areas, this will usually be noted in the report. Good preparation helps avoid unnecessary limitations.

For more detail on the inspection structure, you can internally link to your article on what happens during a TM44 inspection.

Documents that help with a faster TM44 report

For industrial estates and multi-unit parks, documentation is especially useful because equipment can be spread across several units and external areas.

Before booking, landlords and managing agents should try to gather:

• Current AC asset list
• Maintenance reports
• F-Gas leak check records
• Equipment schedules
• Floor plans or unit layout plans
• Tenant access details
• Roof access information
• Plant room access details
• Previous TM44 reports, if available
• Lease or responsibility notes, where relevant
• Details of decommissioned or unused systems
• Contact details for site representatives

You do not need everything before contacting us. Many clients approach TM44.uk with only a site address and rough equipment count. We can still guide you through what is needed. However, better information normally means a faster quote, smoother inspection and cleaner report.

If you manage several sites, our TM44 portfolio management service may be more suitable than booking each property separately.

Case study example: multi-unit trading estate with hidden AC compliance risk

Consider a realistic example.

A managing agent controls a small trading estate with 14 industrial units. The units are leased to a mix of businesses: a print company, trade counter, small gym, plumbing supplier, online retailer, workshop, and two office-based tenants. The landlord assumes TM44 does not apply because the site is mostly industrial.

During a compliance review, the agent discovers:

• Unit 3 has two wall-mounted split systems in a first-floor office
• Unit 4 has a cassette system in a trade counter
• Unit 7 has cooling in a small server room
• Unit 9 has two systems serving a showroom and admin office
• The estate office has a small split system
• Several external condensers are mounted behind the units
• No central asset list exists
• Maintenance records are held by different tenants
• The landlord controls some external areas but not all internal systems

No individual system looks significant in isolation, but the combined installed cooling capacity across relevant areas may exceed the TM44 threshold. The managing agent now has a potential compliance gap and no clear record of when systems were installed or last assessed.

A TM44 inspection in this situation provides more than a report. It gives the managing agent a clearer view of the air conditioning assets, the systems that were accessible, the likely efficiency concerns, and the documentation gaps that need attention.

The result is a stronger compliance file, better visibility of estate-level risk, and a practical set of recommendations for improving future maintenance and energy management.

Case study example: business park office units with expired TM44 reports

A property company owns a modern business park with eight office and light-industrial buildings. Several buildings have reception areas, meeting rooms, open-plan offices and kitchen spaces. Each building has split and multi-split air conditioning systems.

The site had a TM44 report completed years ago, but the report expired and nobody picked it up because the facilities manager changed and the reminder was never transferred.

The issue only comes to light when a tenant requests compliance evidence during a lease renewal. The landlord checks the old file and realises the TM44 report is out of date.

This is common. TM44 inspections are generally periodic, so the main business risk is not always the first inspection. It is the renewal cycle. Reports can quietly expire in the background.

In this case, TM44.uk would review the site information, confirm the inspection scope, arrange attendance, inspect accessible systems, prepare the updated report, and help the client restore a cleaner compliance position.

For this topic, internally link to your guide on what happens if a TM44 certificate has expired and your TM44 certificate service page.

Why TM44 matters beyond legal compliance

Many businesses treat TM44 as a paperwork requirement. That is a weak way to look at it.

On industrial estates and business parks, inefficient air conditioning can create real operating cost problems. Cooling may be running in empty offices, heating and cooling may operate at the same time, controls may be poorly set, filters may be neglected, and old systems may be consuming more electricity than necessary.

A good TM44 report can highlight issues such as:

• Cooling running outside occupied hours
• Poor temperature control
• Old or inefficient equipment
• Poor zoning
• Blocked filters or poor maintenance evidence
• Oversized or undersized systems
• Missing maintenance records
• Poor user control
• Unnecessary cooling of low-occupancy areas
• Opportunities for improved controls or replacement planning

For landlords and agents, this can also support ESG reporting, tenant engagement, service charge transparency and asset management. A better-managed air conditioning system can reduce energy waste and improve the perceived quality of the building.

If your audience is interested in cost reduction, link naturally to energy efficiency upgrade reports after TM44 and your blog on top TM44 fixes to cut energy bills.

Industrial estate landlords should not wait for a warning letter

Waiting until a warning letter arrives is not a good compliance strategy. By that point, the issue becomes urgent. You may need to arrange access across multiple units, gather missing records, contact tenants, check old maintenance documents, and coordinate an assessor visit quickly.

This is much harder on a multi-unit site than on a single office.

A proactive review is usually cheaper, calmer and cleaner. It gives the landlord or managing agent time to understand the asset position, identify any access issues, and book the inspection properly. It also helps protect lease renewals, insurance reviews, sale due diligence and management reporting.

If a client has already received enforcement correspondence, link to your article on TM44 warning letters in the UK and your page on TM44 enforcement, fines and penalties.

How TM44.uk helps industrial estates and business parks

TM44.uk provides air conditioning inspections for commercial buildings across the UK, including industrial estates, trading estates, multi-unit business parks, warehouses with offices, landlord-controlled commercial blocks and mixed-use commercial sites.

Our service is designed to make the process straightforward for landlords, managing agents and occupiers. We can help you understand whether your site may require a TM44 inspection, what information is needed, how to prepare access, and how to organise the inspection with minimal disruption to tenants.

Our TM44 services can include:

• Initial compliance review
• Quote based on site and asset information
• TM44 air conditioning inspection
• Review of accessible systems and records
• Report preparation
• Government lodgement where required
• Portfolio support for multiple sites
• Renewal reminders
• Practical recommendations to improve energy efficiency
• Guidance where asset lists or records are incomplete

For urgent situations, we also offer an emergency TM44 24/48 hour service where availability allows. For larger landlords and managing agents, our portfolio TM44 management service can help organise multiple properties under one structured compliance approach.

To request pricing, use our TM44 quote form and send any available information about the site, number of units, AC systems and maintenance records.

When should you book a TM44 inspection?

You should consider booking a TM44 inspection if:

• Your industrial estate or business park has air conditioning systems with a combined cooling output over 12kW
• You manage multiple commercial units with split or multi-split systems
• You do not have a valid TM44 report on file
• Your previous TM44 report has expired
• The site has recently been refurbished or reconfigured
• Tenants have added air conditioning systems
• You are preparing for a lease renewal, sale or refinance
• A tenant, buyer, solicitor or insurer has requested AC compliance evidence
• You are compiling a compliance file for the property
• You manage a commercial portfolio and want to reduce risk

If you are not sure, it is better to check early. A short review can prevent a bigger compliance problem later.

Final thoughts

Industrial estates and multi-unit business parks are exactly the type of commercial property where TM44 compliance can be missed. The systems are often spread across different units, installed at different times, managed by different parties, and recorded inconsistently. One tenant may have a small split system. Another may have cooling in an office. A landlord may control shared areas. A previous occupier may have installed equipment that nobody has added to the current asset list.

Individually, these systems may look minor. Collectively, they may create a legal requirement for a TM44 inspection.

For landlords, managing agents and commercial property owners, the safest approach is to treat TM44 as part of the wider property compliance file. Check the air conditioning asset position, confirm whether the 12kW threshold may apply, review existing reports, gather maintenance records, and book an inspection before the issue becomes urgent.

TM44.uk supports industrial estates, business parks and multi-unit commercial properties nationwide. Whether you manage one estate or a wider portfolio, we can help you confirm the position, arrange the inspection, prepare the report and keep your compliance records in order.

To get started, request a quote through our TM44 inspection quote page or use the TM44 checker for a first-stage compliance check.