HEAT RECOVERY
Why a compliance-led approach to ventilation hygiene is crucial to heat recovery
Ventilation hygiene is essential to the efficiency of heat recovery systems. In the wake of the launch of the TR19 Air Ventilation Hygiene Register (VHR), which encourages an evidence-based approach to keeping duct cleaning in check, Gary Nicholls, managing director of Swiftclean and co-author of BESA TR19 Air, explains why a compliance lead approach is key to safety, air quality and efficiency
D
irty ductwork and air handling components harbour dust, debris and microbiological contamination, affecting indoor air quality and increasing pressure drop.
Over time, these issues can put pressure on fans, leading to energy wastage as well as wear and tear, while undermining comfort and contributing to non- compliances identified during audits, safety reviews or incident investigations. A hygiene regime that is reactive and/or is too tied to fixed schedules that ignore condition, occupancy changes and filtration performance, will compromise heat recovery operations and leave maintenance teams open to expensive repairs, breakdown and possible insurance issues. To encourage an evidence-based approach to ventilation hygiene, in March, the TR19® Air and the Vent Hygiene Register (VHR) certification pathway was launched. The VHR gives duty-holders a clearer route to specify, procure, report and monitor ventilation hygiene, moving from ‘cleaning because it’s due’ to risk-based, measured maintenance, triggered by usage, system condition and verified outcomes. With clean air pathways, effective filtration and unobstructed heat exchange surfaces so crucial to the efficient running of heat recovery units, the VHR is a key step to ensuring operational certainty, compliance and crucially, occupant health and wellbeing.
TR19 - keeping air clean and reducing fire risk
TR19 is published by the Building Engineering Services Association (BESA) and sets out how ventilation systems should be inspected, tested and cleaned. TR19 Air aligns with BS EN 15780 and provides a workable framework for managing cleanliness across general ventilation systems.
The specification distinguishes between kitchen extract (TR19 Grease, focused on fire risk) and general ventilation (TR19® Air, focused on air flow, hygiene and cleanliness). Many estates need both, and both benefit from consistent inspection, access provision and record keeping. TR19 Grease has had its own VHR since 2019.
Risk-based classification, inspection and verification
TR19 Air uses a risk-based cleanliness classification (high, medium or low) in line with BS EN 15780, based on occupancy vulnerability and space activity. One building can contain multiple classifications, so inspection plans and
Competence is key
VHR members must use technicians that are trained and assessed against recognised BESA competence standards. Two core courses underpin ventilation hygiene competence:
• Air Hygiene Operative (AHO) – For technicians carrying out inspection, access and cleaning. Covers system recognition, safe working, containment and cleaning methods aligned to TR19® Air, with theory and practical assessment.
• Air Hygiene Technician (AHT) – For supervisors/managers who plan works and verify cleanliness. Extends into risk assessment, hazardous contamination, moisture risks in air handling sections, and the legal/commercial implications of non-compliance.
BESA TR19 Air courses are delivered through the Swiftclean Academy. For more information, visit: https://www.swiftclean.
co.uk/besa-air-hygiene-courses-tr19-air/
scopes should be zoned accordingly. Classification informs inspection frequency and when cleaning is required, ascertained by an initial risk assessment to identify contamination levels. Visual inspection is commonly supported by quantitative tests like the European Vacuum Test (EVT) and Deposit Thickness Test (DTT). From this assessment, acceptable contamination levels are defined for supply, recirculation, and extract ductwork. When these levels are exceeded, or when airflow is reduced by 15% or more, cleaning is required.
After cleaning, surfaces must be inspected and be visibly clean, as well as meeting stringent post-clean levels (<0.3 g/m2 using EVT). This information is recorded in a post- works verification report (PWVR), which documents the extent of cleaning, methods used, testing results, and recommendations for future maintenance. Inspection intervals are recommended based on system quality class - typically every 6 to 12 months for most commercial systems.
VHR Air: making ventilation hygiene auditable
The Vent Hygiene Register (VHR) provides a formal certification route for compliance with TR19 Air. For clients and duty-holders, it is intended to provide confidence that
inspections, cleans and reporting processes are delivered by organisations with verified competence.
VHR-certified work is supported by structured
reporting (scope, system details, findings, verification results and photographic evidence). Used consistently, those records help teams spot recurring contamination, test whether filtration is effective and justify targeted interventions based on condition rather than pre-defined schedules. Ultimately, the VHR supports a predictive approach to maintenance, which should be the gold standard in modern building management.
Practical steps for duty-holders and FMs
• Document the cleanliness class – Agree high/medium/low classification for each system/zone and keep it with asset records.
• Inspect first; clean on evidence – Use TR19 Air guidance to create a baseline for cleaning adjusted for condition and operational change (refurbishments, new tenants, altered hours, process changes).
• Include connected components in scope – Filters, AHU internals, fans, dampers and heat recovery sections should be addressed as one system.
• For HRV/MVHR: manage filters and moisture – Maintain filters, check condensate trays/drains and keep exchanger cores clear to protect efficiency and hygiene.
• Verify outcomes – Combine visual standards with quantitative testing where required (e.g., European Vacuum Test for high class systems).
• Keep audit-ready reports – Retain scope, before/after photos and verification results as part of your compliance record.
• Choose competent operatives – Enlist the support of TR19 trained technicians or upskill in-house teams, using BESA- approved training centres and courses.
TR19 Air supports indoor air quality, protects
HVAC performance and strengthens compliance, including heat recovery equipment that can otherwise become a source of efficiency loss and hygiene risk. The goal is simple: risk-based inspection, competent delivery and verification you can stand behind.
10 BUILDING SERVICES & ENVIRONMENTAL ENGINEER MAY 2026 Read the latest at:
www.bsee.co.uk
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