A method for estimating occupant carbon dioxide generation rates

In most applications of indoor CO2, such as building ventilation rate estimation and demand-controlled ventilation, the CO2 generation rate of building occupants is a crucial parameter. Currently, ASTM D6245-18 provides an estimation formula for the CO2 generation rate, but there are indications that its results tend to be underestimated. This paper utilized more than 7,200 sets of CO2 generation rate data from over 1100 participants aged 5 to 70 to propose a segmented regression model for estimating CO2 generation rates based on gender, age, and activity intensity as independent variables. Based on the patterns of CO2 generation rate with age and metabolic rate, two critical age breakpoints were identified: 9/10 years for girls/boys entering puberty and 13/15 years for girls/boys entering the stable growth phase. The reliability of the established model was validated through literature-based data across various scenarios. The results revealed that using the activity intensity determined by the recommended metabolic rates in the ASHRAE Handbook, our estimations were closer to the experimental values compared to ASTM D6245-18, which required higher metabolic rates for compensation. The prediction method in this paper requires only age, gender, and activity metabolic rate to estimate the mean CO2 generation rate for different population groups, offering a simple calculation approach for key parameters in CO2 applications within buildings.