An evaluation of CO2 emission rates by Chilean school children

The predicted and measured carbon dioxide (CO2) emitted by human respiration into an occupied space has been used as an indicator for controlling buildings' ventilation rates. However, this application assumes a constant emission rate for the entire population. Conversely, new knowledge has shown that this variable depends on the number of people in the room and their sex, diet, height, and above all, body mass and metabolic rate. This paper applies the latter model and a previously used sampling approach to identify the variability of CO2 emission rates and excess CO2 concentrations in school classrooms in Chile, and compares them with those in the USA. This time, we collected data from local sources and public databases to model an evidence-based average classroom of 29 students –15 men and 14 women– following the Chilean regulations and the ASHRAE 62.1 and SHRAE 241 standards for ventilation. Then, using Python and a Monte Carlo sampling approach, we calculated the emission rates for the local population in the classrooms of children between 5 and 18 years old. Results show that the mean body weights of the USA and Chilean child populations are statistically different, but the excess CO2 concentrations can vary by only 4% between demographics. The difference in excess CO2 concentrations between countries reflects their differences in occupancy densities. Finally, there is a significant difference in excess CO2 concentrations for the two standards but little difference between countries for the same standard.