TR19® Air Version 2 (2026): What's Changed

TR19® Air Version 2 is the 2026 update to the BESA specification for the cleanliness of ventilation systems, and it is the most significant refresh to air ductwork hygiene guidance in years. If you manage supply and extract ventilation in offices, schools, healthcare or any occupied building, the changes affect how your systems are assessed, how cleanliness is measured and how the results are reported and stored. This authority guide walks through what has actually changed in TR19® Air Version 2 and what it means for building owners and facilities managers.

What is TR19® Air and how does Version 2 differ?

TR19® Air is the part of the BESA guidance dealing with general ventilation ductwork — the supply and extract systems that move air around a building — as distinct from TR19® Grease, which covers kitchen extract. It sits alongside the European standard for ventilation hygiene and sets out how to assess whether ductwork is clean, how to clean it, and how to verify the outcome. Version 2 keeps that core purpose but modernises the method and the paperwork: it tightens how cleanliness is measured, standardises reporting, and links the whole process to a central digital register so results are traceable rather than sitting in a folder somewhere.

How does Version 2 integrate with the Vent Hygiene Register (VHR)?

The headline change is integration with the Vent Hygiene Register (VHR). Rather than compliance evidence living only in a contractor's report, Version 2 aligns the process so that verified cleaning records can be logged to a central register. For a building owner that means an auditable, tamper-resistant trail: when a system was assessed, what class it met, what work was done and by whom. It raises the bar on accountability and makes it much harder for sub-standard work to pass as compliant, because the record follows the asset rather than the invoice. For facilities managers overseeing multiple sites, a central register is a far more defensible position at audit than a scattering of PDFs.

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What is standardised Section 9 reporting?

Version 2 places a strong emphasis on standardised post-clean reporting, structured around a consistent reporting section (commonly referred to as Section 9). The intent is to remove the variation that used to exist between contractors, where one company's "report" might be a photo and a line of text and another's a detailed technical document. A standardised report template means every job is documented the same way — scope, access limitations, measured results, before/after evidence and recommendations — so a facilities manager, auditor or incoming contractor can read any report and understand exactly what was and was not achieved. Consistency here is what makes cross-site comparison and genuine benchmarking possible.

What are Deposit Thickness Tests (DTT)?

On the measurement side, Version 2 formalises the Deposit Thickness Test (DTT) as the way to quantify how much dust and debris has built up on internal duct surfaces. Instead of relying on a subjective "looks clean" judgement, DTT gives a measured figure for the deposit present, taken at representative points along the system. That number is what determines whether a section needs cleaning and whether it has passed after cleaning. Bringing DTT to the front of the process replaces or augments older, less repeatable measures and makes cleanliness verification objective — a reading you can put in a report and defend, rather than an opinion.

How does BS EN 15780:2025 fit in?

TR19® Air Version 2 aligns with the updated European standard BS EN 15780:2025, which defines cleanliness classes for ventilation ductwork. That standard groups systems into cleanliness classes according to the sensitivity of the space they serve — a hospital or laboratory demands a higher standard than a warehouse, for example. Version 2 works hand in hand with these classes: the required cleanliness level for a given building drives the acceptance criteria, and the DTT measurement is judged against the class the system needs to meet. In practice this means the target is set by what the space is used for, not a one-size-fits-all threshold, and your report should state which class was assessed against.

What should building owners and facilities managers do now?

The practical takeaways are clear. First, expect measured evidence: a compliant clean under Version 2 should give you DTT readings and a standardised report, not just photos. Second, ask whether your contractor can log results to the Vent Hygiene Register, because a central record is far stronger at audit. Third, make sure the cleanliness class being applied matches the sensitivity of your building. And finally, treat air duct hygiene with the same seriousness as kitchen extract — the principles of measurement, evidence and documentation now run across both. If you also manage kitchen extract, our guide on what TR19® Grease requires covers that side, and you should keep fire damper testing on the same maintenance calendar so nothing slips.