Do current ventilation codes and standards permit CO2 based ventilation control?
If a code requires ventilation to be provided to a space in terms of cfm/person, CO2 based ventilation measurement can be used to verify compliance to the code or to control ventilation rates to code required levels (e.g. 15 cfm/person). All local codes and standards draw recommendations for ventilation from one of two references: ASHRAE Standard 62-1999 “Ventilation For Acceptable Indoor Air Quality” or the International Mechanical Code (IMC). It is these documents that have established the target cfm/person ventilation rates included in all codes today. In the ASHRAE Standard 62, CO2 based ventilation control is applied under the prescriptive Ventilation Rate Procedure. In this procedure there is a provision for intermittent and variable occupancy that allows the total ventilation rate to a space to be varied as long as the target cfm/person ventilation rate is maintained for the actual occupancy of the space. ASHRAE interpretation IC 62-1999-33 provides further details specific to v
