CO2 monitoring that shows when a room is under-ventilated for the people in it.
CO2 is the most practical everyday proxy for whether ventilation keeps up with occupancy. Aqueduct reads CO2 sensors per zone, tracks peaks and exposure in zone-hours, and flags rooms where levels stay high while people are present.
CO2 rises with people and falls with fresh air. The gap is the signal.
What is measured
- CO2 in ppm per zone
From wall or ceiling sensors placed at breathing height, away from doors and supply diffusers.
- Peak site average
The highest average CO2 across a site's zones, used to rank sites in the portfolio.
- Exposure in zone-hours
Hours each zone spent above its threshold, so a long moderate excess is not hidden by a short spike.
Three common patterns
- Ventilation lagging occupancy
CO2 climbing through meetings and classes, then falling after people leave.
- Fixed minimum outdoor air
Levels that track headcount all day because outdoor air never rises with demand.
- Economizer or damper faults
High CO2 while outdoor air is mild and the dampers should be open.
Why CO2 is worth watching.
lower cognitive scores were linked to a 400 ppm rise in CO2 in a controlled office study.
Source: Allen et al., Harvard, 2016is the alert level for CO2 monitors in classrooms funded by California's CalSHAPE program.
Source: California Energy CommissionAn example
In the demo tenant, a manufacturing site shows a 976 ppm peak site average, the highest in the portfolio, and is rated Unhealthy. Opening it lists the zones in breach and the occupied hours when they breached. Demo data.
Limits
CO2 is a proxy, not a measure of every pollutant: a room can read 600 ppm and still carry high VOCs or particulates. Because it tracks people, an empty, poorly ventilated room reads well.
Sensors need periodic calibration checks by your installer.
Related
Common questions
It depends on the guideline you follow, so aQ AirSafe sets thresholds per site. For example, California CalSHAPE-funded classrooms must alert above 1,100 ppm. Harvard COGfx research also linked higher CO2 to lower cognitive scores. See indoor air quality compliance.
Yes. Demand-controlled ventilation raises outdoor air as CO2 rises and trims it as rooms empty, where control is enabled, with owner approval. The energy effect is then measured against a baseline. See AI optimization.
Not always. Existing CO2 sensors join if they send telemetry, and gaps are filled with LoRaWAN sensors through partners. Sensors go at breathing height, away from doors and supply diffusers. See air quality sensors.
Peak site average CO2 shows which buildings struggle most to ventilate for their occupants. aQ AirSafe ranks sites by it, so a portfolio manager knows where to send the engineer first. See portfolio benchmarking.
See Aqueduct on your own facility.
Bring a site, a utility bill or a question. We will show you where the loss is.