Indoor air quality (IAQ)

Indoor air quality (IAQ) refers to the state of the air breathed in enclosed spaces (offices, shops, homes, schools) and its impact on health, comfort, and performance. It results from a balance between ventilation (fresh air supply), emissions (materials, furniture, activities, processes), maintenance (filters, cleaning), control (building management systems/timers), and the external environment (pollutants, pollen, traffic). Good IAQ reduces headaches, fatigue, and absenteeism, protects equipment (from fouling), and improves decision-making… all while optimizing energy consumption if ventilation is properly regulated.

QAI: definition and operational levers

Operationally, indoor air quality (IAQ) is monitored using indicators:

- CO₂ (occupancy proxy),- total/specific VOCs (solvents, formaldehyde),- fine particles (PM₂.₅/PM₁₀),- humidity (RH),- temperature,- sometimes radon or ozone depending on sites.

Common targets in the service sector:

- Controlled CO₂ (approximately 800–1000 ppm in occupancy), - Low PM₂.₅ (filtered air), - RH 40–60% for comfort and microbial viability.

The levers:

- Ventilation : sized (hygienic flow rates), regulated on demand (CO₂/VOC/presence), balanced (pressure, clean vents), seasonal free/night-cooling for purging.

- Filtration : suitable classes (fine filters on fresh/recycled air), airtight seals, replacement plan.

- Materials/furniture : low emissions (paints, glues, panels), purging time before delivery.

- Maintenance : Clean AHUs, treated siphons/vents, non-emissive cleaning.

- BMS control : schedules in line with occupancy, bypass exchangers if needed, ΔP filter alarms, CO₂/PM monitoring.

- Architecture : buffer zones, solar protection (limit overheating → fewer secondary emissions), air intakes away from polluted external sources.

QAI project: advantages, limitations and points of attention

Interests

• Health & comfort: fewer symptoms (irritations, headaches), increased productivity.
• Operation: less clogged equipment, fewer complaints.
• Controlled energy: with demand regulation, we only need to ventilate as needed.

Boundaries

• Measuring costs money (sensors, calibrations) and requires analysis time.
• VMC/energy conflicts: over-ventilation = kWh; under-ventilation = degraded IAQ.
• Outdoor pollution: requires superior filtration and choice of air intakes.

Points to consider

• Design: compliant flow rates, watertight networks, acoustics (avoid occlusion by users).
• Regulation: CO₂/VOC/presence, realistic scheduling laws, secure night-cooling.
• Filtration: level adapted to the context (urban, pollen, construction dust), ΔP monitoring.
• Materials: prioritize A+ / low emissions; plan a post-work break-in period.
• Maintenance: filter schedule, cleaning of vents/AHUs, balancing checks.
• Sensors: representative placement, periodic calibration, readable dashboards (condominium manager, operator).

Anecdote — “The air that woke up Montreuil”

In Montreuil, multi-tenant offices were experiencing both afternoon fatigue and complaints about unpleasant odors. CO₂/PM monitoring revealed spikes at 2 p.m. (meeting rooms) and clogged filters. Actions taken included: demand-responsive air quality control (CO₂ sensors in the rooms), staggered meeting times, new filters, and nighttime cooling during the summer. The result: CO₂ levels kept below 1000 ppm under load, PM₂.₅ reduced by half, and complaints plummeting. One tenant summed it up: "Even coffee tastes better when the air is clean."