Most commercial HVAC was historically designed for a worst-case occupancy ("full conference room, all day, every day") and operated to that level whenever the system ran. The result: enormous energy waste on most days. Demand-controlled ventilation (DCV) replaces the fixed schedule with real-time control driven by what's actually in the room.
The mechanism is straightforward: CO2 sensors in each occupied zone feed the building management system (BMS), which modulates the outdoor-air damper position to keep CO2 at a target setpoint (typically 800-1,000 ppm). When the room empties, CO2 drops, the damper closes, and the system saves energy. When occupancy spikes, CO2 rises and the damper opens further before anyone notices stuffiness. LBNL's DCV review documents 10-30% HVAC energy savings in typical commercial buildings.
ASHRAE 62.1 explicitly permits CO2-based DCV for spaces with variable occupancy. Most modern BMS systems support it natively; older buildings often need a controls upgrade rather than ductwork changes. The economics generally make sense above ~500 m² of conditioned space with variable occupancy patterns.
For a Terrestream commercial deployment, the sensor data can be exposed to the BMS as a CO2 input (MQTT, BACnet via gateway, or REST polling) where the building automation can use it for DCV setpoints. This is the use case the API plan supports out of the box. The same data also satisfies RESET Air continuous-monitoring reporting requirements at no additional cost.
References
- ASHRAE Standard 62.1 - Ventilation for Acceptable Indoor Air Quality www.ashrae.org
- LBNL - Demand-controlled ventilation review doi.org
- ASHRAE Handbook (HVAC fundamentals) www.ashrae.org
- Persily - Indoor CO₂ and ventilation doi.org
