CO₂ detection is the measurement of carbon dioxide concentration in indoor spaces to monitor air quality and control ventilation systems.
How does CO₂ detection work?
Carbon dioxide is a natural byproduct of human respiration. In enclosed spaces such as offices, classrooms and residential buildings, CO₂ levels rise as occupants breathe. A CO₂ sensor continuously measures the concentration in parts per million (ppm). When levels exceed a set threshold — typically around 800 to 1000 ppm — the sensor sends a signal to the building management system (BMS) to increase the ventilation rate.
Most sensors use non-dispersive infrared (NDIR) technology, where an infrared light source passes through a sample chamber. CO₂ molecules absorb specific wavelengths of that light, and the sensor calculates the concentration from the remaining signal strength. These sensors are accurate, stable over time and require minimal maintenance.
Why is CO₂ detection important in buildings?
Elevated CO₂ levels indicate insufficient fresh air supply. Poor indoor air quality leads to headaches, fatigue and reduced concentration among occupants. Building regulations in many countries now require demand-controlled ventilation (DCV) in non-residential buildings, making CO₂ sensors a standard component of modern HVAC design.
Applications
- Demand-controlled ventilation in offices and schools
- Monitoring air quality in meeting rooms and lecture halls
- Controlling natural ventilation openings in façade systems
- Verifying performance of mechanical ventilation installations
- Green building certification (BREEAM, LEED) documentation
Related terms
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