Which indicators are commonly used to control DCV?

• A. CO2 concentration or other appropriate contaminants.
• B. Outdoor temperature.
• C. Relative humidity.
• D. Wind speed.

Answer: (A)

Demand-controlled ventilation adjusts the amount of outdoor air based on an indoor air quality or occupancy signal, so ventilation rises when people are present and IAQ needs higher dilution, and falls when spaces are sparsely occupied. The most common indicator is CO2 concentration, because occupants exhale CO2 and its level serves as a practical proxy for occupancy and contaminant generation. Systems can also use other appropriate contaminants as indicators if a space’s IAQ objective is better represented by substances like VOCs or particulates. This approach helps maintain IAQ while conserving energy by not always ventilating at the maximum rate. Outdoor temperature, relative humidity, and wind speed are not typical indicators for DCV, though they may influence other controls such as economizers or humidity management.