“Healthy” Demand Control Ventilation – Why multiparameter sensor platforms are a better option than CO2-only sensors
Today’s multiparameter sensor platforms account for both people and pollutants. In addition to just carbon dioxide (CO2) sensing – now particulate matter (PM) airborne chemicals (TVOC), and other contaminants can be measured, analyzed and reported inside offices, classrooms and healthcare facilities. Most multiparameter indoor air quality sensor platforms are now available with enhanced dashboard visualization, integration features – and communicate wirelessly. As a result, Healthy Demand Control Ventilation” is becoming the smarter choice, especially considering facility owners and managers are facing significantly increased pressure for documenting sustainability measures that contribute to a healthy and energy efficient building.
For several decades Carbon Dioxide (CO2) -only based DCV sensing has been used primarily to conserve energy by reducing ventilation using CO2 as a proxy for the number of people in the space. It has met with limited success for two reasons: First, the costs for calibrating these non-dispersive infrared instruments compromised the savings, or calibration was simply not performed, thus readings drifted to the point where they became unreliable for ventilation control. Secondly, CO2-only does not account for pollutants (e.g., PM, VOCs, Ozone ) that may be present regardless of the number of the people in the space.
Since the beginning of the pandemic there has been tremendous emphasis on filtering particles, since they are the carriers of the smaller pathogens that contribute to higher infection rates. Despite the availability of laser-based sensors that measure respirable size particles (e.g., .3 to 2.5 micrograms per cubic meter of air), very few commercial spaces are taking advantage of this measurement. Unless there is measurement, how does a facility know if their levels are meeting established thresholds for particle levels in an occupied space? How do they know if their filtration is performing, or if they need to upgrade, or if they need to supplement with room air purification units?
The same is true of chemical levels in the air. Are TVOC thresholds being met? Is the off-gassing from furnishings or building materials below threshold guidelines. What about enhanced cleaning practices – is more ventilation air needed for dilution?
Just as a pilot relies on his instruments to fly, facility managers need measurements so they manage ventilation and filtration decisions. Flying blind in our data driven and health conscious world is no longer acceptable!