Carbon dioxide (CO2)-based demand control ventilation (DCV) automatically adjusts building ventilation rates based on indoor CO2 concentration. Since the indoor CO2 concentration is directly related to the occupancy, the purpose of CO2-based DCV is to conserve energy by reducing the ventilation rates during periods of low occupancy. In this work, two standard testing protocols for CO2 sensors and CO2-based DCV system controllers are developed and performed on several currently available CO2 sensors and DCV system controllers. Test results are provided and discussed.