Guidance
Poor Ventilation in Offices
How to recognise, measure and remediate under-ventilation in UK office buildings — the single most common root cause of workplace IAQ complaints.
The pattern
Under-ventilation is the root cause of most office IAQ complaints
Most UK office buildings are designed to deliver enough fresh air. Few actually do — five years after handover. Filter loading, damper failures, BMS overrides, increased occupant density and altered occupancy patterns (hybrid working, denser hot-desking) all reduce the fresh-air rate per person below the design intent.
The result is rising CO₂, accumulating VOCs and bioeffluents, and the symptom cluster occupants describe as "stuffy" or "stale". Approved Document F (2021) requires offices to maintain CO₂ below 1500 ppm daily-average. Buildings routinely measure 1800–2500 ppm during peak occupancy — a clear, measurable failure of the ventilation strategy.
Benchmarks
Ventilation targets
| Metric | Standard | Target |
|---|---|---|
| Outdoor air rate | AD-F 2021 | ≥ 10 l/s/person |
| CO₂ (daily average) | AD-F 2021 | ≤ 1500 ppm |
| CO₂ (good practice) | BS EN 16798-1 Cat II | ≤ 1000 ppm |
| Filter grade (offices) | BS EN ISO 16890 | ePM1 ≥ 50% |
| BMS occupancy strategy | CIBSE TM40 | Demand-controlled |
FAQ
Poor office ventilation
Diagnose under-ventilation accurately
Independent ventilation audit and CO₂ monitoring across affected zones. Call 01322 555566.
Request an investigation