Signs of poor office ventilation

Afternoon drowsiness, headaches in meeting rooms, dry eyes, lingering odours, a general sense of stuffiness that improves within an hour of leaving the building. Symptoms cluster by zone and by day of week.

Steady-state CO₂ above 1500 ppm in occupied zones, a sharp morning rise that plateaus around lunch, then a second peak by 4pm. Meeting-room peaks above 2000 ppm. TVOC concentrations that fail to fall when occupancy drops.

Start with a two-week continuous monitoring baseline. Confirm AHU is delivering design rate. Rebalance, recommission, then upgrade to demand-controlled ventilation where the data supports it.