Most building owners and facilities managers know their ventilation has rules attached. Far fewer could say with confidence who holds each duty, particularly in a leased building where responsibility is split between landlord, tenant and managing agent.
Here’s how the picture usually breaks down, and where we see it go wrong.
The duty usually sits with the person in control
In broad terms, responsibility follows control of the premises. The employer or occupier has duties for the working environment. The building owner or landlord typically has duties for the plant and the structure. Where a managing agent runs the building, they act on the owner’s behalf, but the duty doesn’t disappear into the contract.
Where this gets messy is in multi-tenanted buildings with shared plant. Landlord-owned AHUs serving tenant-controlled spaces are a common source of confusion, particularly when the tenant has altered layouts and the ventilation no longer matches the use.
Whatever the lease says, the practical test is whether someone is actually carrying out the duty. Nobody is helped by two parties each assuming the other has it covered.
What you’re complying with
Several separate regimes sit over commercial HVAC:
Workplace ventilation. Employers have to provide adequate ventilation of the workplace. That’s the starting point for most offices, warehouses and factories.
Building regulations. New work and significant alterations have to meet current standards. Our guide to building ventilation regulations 2026 covers the current position.
Water hygiene and Legionella. Any system holding or introducing water brings a duty to assess and manage the risk. See Legionella and your air handling unit.
F-Gas. Systems containing fluorinated refrigerants carry leak checking, record keeping and qualified handling requirements. See our F-Gas regulations and your AHU guide.
Fire safety. Ventilation crosses fire compartments, so dampers have to be present, accessible and tested. See fire and smoke dampers.
Ductwork cleanliness. TR19 is the reference for hygiene and grease management. See TR19 ductwork cleaning.
Sector specific requirements. Healthcare has HTM 03-01. Food, pharmaceutical and clean room environments have their own.
Energy performance. Assessments and reporting requirements apply to many commercial buildings, and ventilation plant forms part of the picture.
Maintenance is the evidence
Nearly every duty above relies on demonstrating that the plant is maintained. That’s where SFG20 comes in, as the schedules most contracts are built around. Our guide to SFG20 AHU maintenance explains how tasks and frequencies are set.
Documentation is what proves compliance after the event. On the buildings we take over from other providers, the most common gap isn’t the work itself, it’s the records. No commissioning data, no damper test records, no water hygiene log, and an asset list that hasn’t been updated since the plant was replaced.
Outsourcing the work, not the duty
You can contract out the work. You can’t contract out the responsibility. What a good contractor gives you is competent people, the right task schedules and the records to prove it, so you can show the duty is being discharged.
That’s what we set out to provide on our AHU maintenance contracts, and what’s covered in AHU maintenance contracts: what’s included.
Practical steps
- Establish who holds what. Read the lease and the service charge schedule, then write down the split.
- Build an asset list of every unit, with location, duty and age.
- Set the schedules against SFG20 and any sector specific requirements.
- Keep the records in one place, including commissioning data, damper tests, water hygiene logs and F-Gas records.
- Review after any change of use. Layout and occupancy changes are what most often leave ventilation non-compliant.
We’ve worked in buildings where nothing can stop while this is put right, from live airport facilities to the units at Dalston Cross and the fan upgrades at Colmore Row. It can be done in stages without disrupting the building.
How we could help
We maintain, refurbish and replace HVAC and air handling plant for commercial buildings across the UK, and we’ll help you get the asset list and records straight as part of taking a site on.
Get in touch to talk it through.
Frequently asked questions
It depends on the lease and on who controls the plant. Landlords typically hold the plant duties, occupiers hold workplace duties, and shared systems need the split agreed explicitly.
Asset list, maintenance records against a recognised schedule, commissioning data, fire damper test records, water hygiene assessments and logs, and F-Gas records where refrigerants are involved.
It gives you the work and the evidence, which is most of it. The responsibility still sits with the duty holder, so the contract needs to cover the right tasks at the right frequencies.
