Preventative Indoor Air Quality Monitoring

Periodic surveys or continuous monitoring

Periodic surveys repeat a controlled method at agreed points in the year. They suit buildings where a representative occupied period can show whether conditions remain stable. Continuous monitors provide a longer stream of data and can reveal short changes that scheduled visits miss, but they also need sensor management, data checks and a defined response process. We help choose the proportionate route. Portable reference instruments may be used to check installed devices, while laboratory sampling is added only when a particular substance requires confirmation.

Seasonal effects worth tracking

Heating season can coincide with closed windows, altered plant schedules and drier indoor conditions. Summer may bring overheating, solar gain, open windows or different outdoor pollutant ingress. Meeting-room use, hybrid-working patterns and holiday periods also change the relationship between occupancy and CO₂. A monitoring plan selects comparable periods and records these influences, allowing the client to distinguish seasonal behaviour from genuine deterioration in controls, maintenance or source management.

• Heating operation and closed-window periods
• Summer overheating and changes in natural ventilation
• Morning plant start-up and pre-occupancy conditions
• Afternoon accumulation in densely used rooms
• Fit-out, cleaning or operational changes between survey rounds

Trend analysis and agreed alert levels

Before data collection, we agree which changes require routine review and which warrant prompt attention. Alert levels can be based on applicable guidance, the building’s baseline and the operational question. They are not interpreted without context: occupancy, outdoor readings, room use and ventilation status are checked alongside the result. Trend reports show sustained shifts, repeated time-of-day patterns and differences between locations. This provides an evidence trail for adjusting plant schedules, reviewing room booking or commissioning a targeted investigation.

Logger deployment and data review

Deployment length depends on the pattern being investigated. Instruments are placed in representative breathing-zone locations away from obvious local interference and are logged against room and asset references. Short studies can capture a defined working pattern; longer studies can compare operating modes or weeks. Data are quality-checked after collection and reviewed at the cadence agreed with the client. Continuous systems need ownership for alerts, device status and missing data, whereas periodic deployments conclude with a discrete report and action review.

When monitoring triggers an investigation

A reactive investigation is recommended when a sustained change, repeated complaint or location-specific peak cannot be explained by normal occupancy and operation. The follow-up may compare indoors with outdoors, review potential material or activity sources, inspect relevant ventilation hygiene or use laboratory sampling. The investigation is scoped from the trend evidence, avoiding an unfocused list of tests. After action, the original measurement approach can be repeated to check whether the pattern improved.