If Only Part of Your Building Has Air Conditioning, Do You Need a TM44 Inspection?

Introduction

If only part of your building has air conditioning, it’s easy to assume TM44 does not apply.

That assumption is where most compliance problems start.

In reality, a building does not need to be fully air conditioned to fall within the scope of TM44. In England and Wales, any air conditioning system with an effective rated output of more than 12kW must be inspected at least every five years.

That rule applies whether the system serves the whole building or just a single area.

If you are unsure how this applies to your property, you can review the full inspection process here:
➡️ https://tm44.uk/tm44-air-conditioning-inspections/

---

The Rule That Actually Matters

The mistake most people make is focusing on how much of the building has air conditioning.

That is not what the regulation looks at.

The only thing that matters is this:

Does the system, or systems under single control, exceed 12kW?

If the answer is yes, the building is likely within scope.

Government guidance is clear on two key points:

• Systems over 12kW require inspection
• Multiple smaller units can be combined if they operate under single control

That means a building can be mostly uncooled and still require a TM44 inspection.

If you are not 100% sure how your system is classified, this is usually the point where a proper review avoids problems later:
➡️ https://tm44.uk/get-quote/

---

Why Partial Air Conditioning Still Counts

A large number of commercial properties only have air conditioning in specific areas.

That is completely normal, and it does not remove the requirement.

Typical setups include:

• Offices with cooling only on certain floors
• Retail units with air conditioning in trading areas but not storage
• Mixed-use buildings where only commercial spaces are cooled
• Medical practices with cooling in treatment rooms
• Warehouses with air conditioning limited to offices or server rooms

In all of these cases, the regulation is based on system capacity, not coverage.

If the combined system exceeds 12kW, TM44 can apply even if most of the building has no air conditioning.

This is exactly why so many properties fall into non-compliance without realising it.
Industry data suggests that a large majority of qualifying buildings are still either non-compliant or unclear on their TM44 status

---

A Simple Example

Take a small office building.

The ground floor has no cooling.
The first floor has four split units rated at 3.5kW each.

At first glance, it looks minor.

But combined, the system is 14kW.

If those units are under single control, the building exceeds the legal threshold.

That means a TM44 inspection is required.

This is one of the most common real-world scenarios where assumptions lead to problems.

---

Mixed-Use Buildings Create Even More Confusion

Mixed-use properties make this even less obvious.

Imagine a building with:

• Residential flats
• A commercial office
• A retail unit

Only the office has air conditioning.

Most people assume TM44 does not apply because the majority of the building is not cooled.

That is not how the regulation works.

The key questions are:

• What system is installed?
• Who controls it?
• What is its total output?

If the commercial system exceeds 12kW under single control, it may still require a TM44 inspection regardless of the rest of the building.

For landlords or managing agents dealing with multiple properties, this is where things get messy without a clear process:
➡️ https://tm44.uk/portfolio-tm44-management/

---

The “Only One Area Has AC” Mistake

This is where most non-compliance starts.

Not because people ignore the rules, but because they misread the situation.

Common reasons include:

• The air conditioning only serves one part of the building
• The system looks too small to matter
• The equipment was installed years ago
• The building layout has changed over time
• The original report is missing
• Responsibility between landlord and tenant is unclear

None of these remove the requirement.

They just delay the moment when it becomes a problem.

---

What Counts as a Single System

The idea of “single control” is critical.

Even if units are spread across different rooms or installed at different times, they can still be treated as one system if they are controlled together.

This includes:

• Split systems across multiple offices
• Ceiling cassettes in different areas
• Systems added over time but managed as one

If they operate under single control and exceed 12kW combined, TM44 applies.

This is one of the biggest areas where people get caught out.

---

Case Study Example 1: Office Above Retail

A building has:

• A retail unit on the ground floor
• Office space above with several AC units

The owner assumes TM44 does not apply because only the office is cooled.

After review, the total system exceeds 12kW.

Outcome: the property requires a TM44 inspection.

This is a common situation where the issue only surfaces when a transaction or audit is already in progress.

If timing is tight, this usually turns into an urgent requirement:
➡️ https://tm44.uk/emergency-tm44-inspection/

---

Case Study Example 2: GP Surgery

A medical practice has cooling in:

• Treatment rooms
• Reception
• One office

The rest of the building is not air conditioned.

The system exceeds 12kW.

Outcome: TM44 applies.

This setup is extremely common across healthcare and commercial buildings.

---

Case Study Example 3: Mixed-Use Property

A building includes:

• Residential flats
• A commercial office suite

Only the office has air conditioning.

The system exceeds 12kW under single control.

Outcome: TM44 still applies.

The requirement is based on the system, not the entire building.

---

Why This Matters More in 2026

This is no longer something that can be ignored.

The rules have been in place for years, but awareness is still low.

That is changing.

More properties are being reviewed, more compliance checks are happening, and more businesses are realising too late that they are missing a valid report.

The issue usually appears at the worst possible moment:

• During a lease agreement
• During a sale
• During due diligence
• During internal compliance reviews

At that point, it becomes urgent.

And urgency usually means higher cost, delays, and unnecessary pressure.

---

How to Check If You Need TM44

If only part of your building has air conditioning, run through this properly:

• Is the system used for occupant comfort?
• What is the total effective rated output?
• Do smaller units combine to exceed 12kW?
• Are they under single control?
• Who is responsible for the system?
• Is there already a valid TM44 report?
• Is it still within five years?

If you cannot clearly answer these, the safest step is to review the system properly.

---

The Practical Reality

Most people do not think about TM44 until something forces them to.

That trigger is usually pressure:

• A transaction
• A compliance check
• A tenant request
• Missing documentation

That is where delays happen.

And that is exactly where this could have been avoided earlier.

---

Final Answer

Yes, you may still need a TM44 inspection even if only part of your building has air conditioning.

The legal trigger is not full coverage.

It is whether the system, including combined smaller units under single control, exceeds 12kW.

If there is any doubt, the smart move is to confirm it early rather than deal with it under pressure later.

If you want to check your building quickly and avoid getting caught out, you can request a review here:
➡️ https://tm44.uk/get-quote/