Subjective and objective evaluation of a CO2-control variable ventilation system.

The heating system of a Junior High School in Minnesota has been re-equipped with a CO2-controlled variable ventilation system. The outdoor air dampers remain fully closed whenever the CO2 concentration is below a specified setpoint. During the early months of 1980, the system operated in alternate periods under the conventilanal temperature-driven control strategy and the experimental CO2-driven control strategy. Measurements obtained indicate that the use of the CO2-based system may yield significant energy savings, while the occupants subjective responses suggested that they felt warmer when the CO2-controlled system operated, despite no measurable difference in space temperature.