Who Is Actually Responsible for TM44 in Complex Buildings? A Practical Guide for Landlords, Tenants & Managing Agents

In commercial property, responsibility is rarely as simple as it looks on paper.

• Documents suggest clarity.
• Leases define obligations.
• Managing agents coordinate operations.

Yet when it comes to TM44 compliance, one pattern repeats across the UK:

Nobody is fully certain who is responsible, and because of that, nobody takes action.

This is not a minor administrative issue. It is one of the primary reasons why the majority of qualifying buildings still operate without a valid TM44 inspection. In many cases, it is not neglect. It is uncertainty.

If you need a foundation on how TM44 inspections work, you can start with the core guide here:
https://tm44.uk/tm44-air-conditioning-inspections/

What follows goes deeper. This is about real-world responsibility, where theory breaks down and risk begins.

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The Illusion of Ownership

One of the most common assumptions in commercial property is that ownership defines responsibility.

If you own the building, you are responsible.
If you rent the space, you are not.

This assumption fails immediately under TM44.

The regulation does not operate on ownership alone. It operates on control, operation, and system structure. This is where complexity enters the picture, especially in modern buildings where air conditioning systems are layered, shared, extended, and modified over time.

A building may have been designed with a central system. Years later, tenants install additional units. Control becomes fragmented. Documentation becomes outdated. Responsibility becomes blurred.

And that is precisely where compliance starts to fail.

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Where Responsibility Actually Sits

To understand responsibility properly, you have to step away from legal labels and look at the system itself.

Who operates it?
Who controls it?
Who maintains it?
Who benefits from it?

These questions define responsibility far more accurately than ownership alone.

In a simple building, this is easy to answer. In a complex building, it becomes a layered structure of overlapping responsibilities.

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Single-Let Buildings: Clear on Paper, Not Always in Practice

In a single-let building, where one tenant occupies the entire property, responsibility often appears straightforward.

The tenant uses the system daily.
The tenant controls internal conditions.
The tenant may even maintain the equipment.

From a practical perspective, responsibility typically sits with the tenant.

However, the lease can change everything.

If the landlord retains control of plant and equipment, or if maintenance obligations are structured in a specific way, the responsibility can shift entirely.

This is where many businesses make a mistake. They assume operational use equals responsibility. In reality, the lease must align with that assumption.

If it does not, compliance gaps begin.

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Multi-Let Buildings: Where Most Problems Start

Multi-let buildings introduce a different level of complexity.

You are no longer dealing with one system and one occupier. Instead, you have:

Multiple tenants
Shared infrastructure
Central plant systems
Independent modifications over time

In most cases, the central air conditioning system is controlled at a building level. That typically places responsibility with the landlord or managing agent acting on their behalf.

But this is only part of the picture.

Tenants frequently install additional units within their own demise. These may be split systems, server room cooling units, or supplementary systems added long after the original design.

Now the building contains multiple systems operating under different control structures.

Some are central.
Some are local.
Some are documented.
Some are not.

At this point, the question is no longer “who is responsible” but rather:

Which system are we talking about?

This distinction is critical. Because under TM44, systems can be assessed individually or as part of a combined capacity.

If you have not already explored how systems combine, this becomes essential:
https://tm44.uk/news-blog/check-tm44-12kw-threshold/

Many buildings unknowingly cross the compliance threshold through accumulation rather than design.

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Retail, Franchises and Split Control Environments

Retail environments create another layer of complexity.

A shopping centre may operate a central cooling system for common areas. At the same time, individual retail units install and operate their own internal systems.

From a structural perspective:

The landlord controls the central system.
The tenant controls the internal system.

Both may fall under TM44.

In theory, each party manages their own compliance.

In practice, neither side often verifies the combined capacity or overall compliance position of the site.

Franchise environments make this even more complex. A national brand may operate multiple sites, each with slightly different system setups, lease structures, and historical installations.

Responsibility becomes inconsistent across locations.

And inconsistency leads directly to risk.

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The Role of Managing Agents

Managing agents are often seen as the operational centre of a building.

They coordinate contractors.
They manage maintenance schedules.
They oversee compliance processes.

But they are not always the responsible party.

They act on instruction.

This creates one of the most common failure points in TM44 compliance.

The landlord assumes the agent is handling it.
The agent assumes the landlord will instruct it.

Nothing happens.

Until enforcement, audit, or transaction forces the issue.

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When Responsibility Becomes a Problem

Responsibility is rarely questioned until it needs to be proven.

This typically happens at critical moments:

During a sale
During a lease agreement
During a compliance audit
After receiving an enforcement notice

At this point, the question is no longer theoretical. It becomes urgent.

Where is the TM44 report?
Who arranged it?
When was it last completed?

If there is no clear answer, the consequences are immediate.

Transactions slow down.
Legal teams get involved.
Costs increase.

You can see how this risk develops in real scenarios:
https://tm44.uk/news-blog/tm44-commercial-property-deal-risk/

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A Real Scenario That Repeats Across the UK

Consider a multi-let office building.

It has a central VRF system installed during construction. Over time, tenants added their own cooling units within individual spaces.

The landlord assumes the managing agent handles compliance.
The managing agent assumes each tenant is responsible for their own systems.
Tenants assume the building is already compliant.

No TM44 inspection is carried out.

Years later, a lease renewal triggers a compliance check.

No valid report exists.

The result is immediate pressure to resolve the situation. The inspection becomes urgent, more complex due to undocumented systems, and more expensive due to time constraints.

This is not an isolated case. It reflects a pattern across thousands of buildings.

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The Real Risk Behind TM44 Responsibility

Non-compliance is often framed as a financial risk.

Fines are part of it. But they are not the main issue.

The real risk is operational.

Unclear responsibility leads to:

Missed inspections
Incomplete records
Delayed transactions
Loss of control over compliance

And as enforcement becomes more structured, these gaps become visible.

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A Practical Way to Think About Responsibility

Instead of asking “who owns the building,” a more accurate approach is to ask:

Who controls the system?
Who operates it daily?
Who maintains it?
Who has the authority to act?

From there, responsibility becomes clearer.

In simple cases, it aligns easily.
In complex cases, it requires coordination.

And coordination is where most businesses fail.

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The Smarter Approach

Experienced operators do not wait for responsibility to become a problem.

They define it early.

They map their systems.
They understand their control structure.
They confirm their obligations.

And then they act.

If there is uncertainty, they remove it.

If responsibility overlaps, they coordinate.

Because the cost of clarity is always lower than the cost of delay.

If you need to move from uncertainty to action, you can start here:
https://tm44.uk/get-quote/

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Final Perspective

Most buildings are not non-compliant because people ignore TM44.

They are non-compliant because responsibility is fragmented, unclear, or assumed.

In complex buildings, that fragmentation increases with every tenant, every system, and every change over time.

The businesses that stay compliant are not necessarily more knowledgeable.

They are simply more decisive.

They do not ask who should act.

They make sure someone does.