Long-term indoor air monitoring
Long-term indoor air monitoring
Indoor air quality is rarely constant. Occupancy, weather, HVAC schedules and seasonal changes all shift the picture across weeks and months. Long-term monitoring captures that full envelope so decisions are made from trend data — not from a single visit.
Programme shape
What a long-term programme typically measures
Long-term deployments combine fixed sensor nodes with periodic deep-dive testing. The parameter set is chosen to surface ventilation, chemistry and comfort issues over time.
3–12 mo
Captures seasonal and occupancy variation.
1–5 min
Continuous logging at fixed intervals.
CO₂ · PM · VOC · T · RH
Core IAQ and comfort metrics.
Monthly
Trends, exceedances and recommendations.
Trend visibility, not snapshots
Multi-month records reveal HVAC drift, filter degradation, occupancy creep and seasonal outdoor influence that a one-off survey cannot.
Calibrated sensor network
Reference-grade nodes deployed across representative zones with traceable calibration and quality-controlled data.
Periodic deep-dive
Quarterly laboratory sampling for formaldehyde and speciated VOCs adds chemistry the continuous sensors cannot resolve.
Action-oriented reporting
Monthly reports flag exceedances against WHO 2021, BS EN 16798-1 and CIBSE TM40 with specific operational recommendations.
When to commission
Where long-term monitoring earns its place
Workplaces tracking IAQ as part of ESG or wellbeing reporting; landlords differentiating on indoor environmental quality; estates with seasonal complaint patterns; and any building where one-off testing has produced inconsistent results.
Often paired with continuous air quality monitoring hardware and indoor air monitoring systems integration.
Benchmarks
Reference values applied to long-term datasets
| Parameter | Reference value | Source |
|---|---|---|
| CO₂ | < ~800 ppm above outdoor (90th pct, occupied) | BS EN 16798-1 Cat II |
| PM2.5 (24-h) | < 15 µg/m³ | WHO 2021 |
| PM10 (24-h) | < 45 µg/m³ | WHO 2021 |
| TVOC | < 500 µg/m³ | WELL v2 Air |
| Operative temperature | 20–24 °C / 23–26 °C | CIBSE Guide A |
| Relative humidity | 40–60 % | ASHRAE 55 / WELL v2 |
Plan a long-term monitoring programme
Multi-month continuous IAQ data with calibrated sensors and a monthly written report.
Request a programme quoteRelated services
Specific parameters