A CO2 monitor measures carbon dioxide concentration in indoor air, typically in parts per million (ppm), to assess ventilation adequacy and indoor air quality. These devices detect whether outdoor air is being supplied in sufficient quantities to dilute accumulated CO2 from human respiration and metabolic activity.
Technical Specifications
CO2 monitors use non-dispersive infrared (NDIR) sensors to measure concentrations between 0-5000 ppm. ASHRAE standards recommend maintaining indoor CO2 below 1000 ppm to ensure adequate ventilation. Many modern monitors display readings in real-time and log data for analysis. Accuracy ranges from ±30 to ±50 ppm depending on sensor quality.
HVAC System Applications
CO2 monitors validate that ventilation systems deliver appropriate outdoor air rates, particularly in demand-controlled ventilation (DCV) systems. They help identify when air handling units are not providing sufficient fresh air supply.
Practical Importance
High CO2 levels (above 1200 ppm) often correlate with occupant complaints about stuffiness, fatigue, and reduced cognitive performance. CO2 data justifies HVAC upgrades and helps tune ventilation controls for energy efficiency while maintaining occupant comfort.