Ventilation Risk Assessment — Hygiene, Contamination & Fire Risk Grading

A ventilation risk assessment is a structured review of the ventilation systems serving a commercial building, scored against a consistent set of hygiene, contamination and fire-risk criteria. It produces a prioritised remediation plan that tells the building owner which systems require attention first and why. It is not a Fire Risk Assessment in the regulatory sense — that remains the role of the building's appointed fire risk assessor — but it is the document an FRA will typically ask to see when the building has kitchen extract, plant room extract or any other system where ventilation contamination is part of the fire risk picture.

Equally, it is not a sales document. Systems that are in good condition and being maintained on an appropriate cycle are recorded as such. The value of the assessment is in identifying genuine risk, not in generating cleaning work.

Three risk axes are scored for every system in scope:

• Hygiene risk — surface dust loading, biofilm, microbial growth and the resulting impact on the air being delivered to the occupied space.
• Contamination risk — process-specific contamination on extract and LEV systems, drain tray condition on AHUs, and the risk of recirculating contaminated air through the building.
• System condition — physical condition of the ductwork, insulation, dampers, access doors and supporting plant. A clean duct in a corroded housing is still a risk.

For kitchen extract and other grease-bearing systems, a parallel fire-risk score is recorded against the BESA TR19 Grease deposit thresholds and the cooking type and hours of the kitchen served.

The combined scoring produces a prioritised cleaning priority list for the building or portfolio. Systems above the action threshold are scheduled for cleaning in the current period; systems approaching the threshold are scheduled for re-inspection within an agreed window; systems comfortably inside the threshold remain on routine cycle. This evidence-based approach typically removes 20–40% of the cleaning that a generic time-based programme would otherwise specify, while bringing the genuinely high-risk systems forward.

For multi-site clients, the same scoring framework lets us roll the assessment up to a portfolio view, identifying the buildings that need the most immediate attention and supporting capital planning for access works, AHU renewals and any other significant remedial scope identified.

The final report is written for two audiences. Operationally, it gives the facilities team a clear, actionable plan. For commercial building risk management purposes, it gives the duty holder a single document to share with insurers, fire risk assessors, incoming tenants and auditors that explains what was assessed, what was found, what is being done and on what frequency the assessment will be refreshed.

We recommend refreshing the assessment annually for buildings with grease extract or high-risk plant, and every two to three years for office-only estates. Routine ventilation system inspections in between feed the next assessment cycle without requiring a full re-survey.

Most ventilation risk assessments lead into one or more of the following workstreams: duct cleaning for systems above the TR19 threshold, TR19 duct cleaning with PCV reporting where insurer evidence is required, extraction duct cleaning for grease-bearing extract, AHU cleaning for plant room hygiene, and an ongoing duct hygiene programme delivered through our ventilation cleaning services.

To commission a ventilation risk assessment for a single building or a portfolio, request a quote, book an inspection or contact us.