HVAC systems and office air quality

BS EN 16798 Category II fresh air, ISO 16890 ePM1 50% filtration, clean coils and condensate, demand-controlled supply linked to breathing-zone CO₂. Result: PM2.5 at 15–30% of outdoor, CO₂ comfortably below 1000 ppm.

Fouled coils contributing microbial odours, bypassing filters letting PM2.5 through, intakes downstream of car park exhaust, humidifiers as reservoirs for microbial growth.

Full HVAC hygiene inspection to BS EN 15780 annually, ductwork to TR/19 every 2–5 years, filter audit quarterly. Pair with continuous IAQ monitoring to verify the outcome.