Proposal for a Simplified Method to Calculate the Concentration of CO2 in a Classroom Using CFD Simulation and Its Experimental Validation

The present study addresses the problems of predicting the distribution of CO2 in a classroom where limited ventilation may compromise air quality. Through Computational Fluid Dynamics (CFD), a detailed analysis of airflow, temperature, and CO2 dispersion was carried out; however, due to its high computational cost, real-time applications are limited. Therefore, this work proposes a simplified CFD approach to model human breathing based on a constant airflow velocity and an average CO2 concentration, preserving mass balance while reducing computational demand. Three mathematical breathing models (constant, complete, and sinusoidal) were formulated and compared through CFD simulation with the classroom model. Subsequently, a CO2 detection module based on SCD40 sensors was developed for the experimental validation of the simplified model, recreating the simulation conditions in a real environment. The results show strong agreement between the simplified model and the complex models, as well as with experimental measurements, with relative errors between 0.05% and 10% at different monitoring points. The proposed model reduced calculation time by more than 98% compared to the sinusoidal model, without compromising accuracy. These results show that the simplified model is an efficient alternative for predicting CO2 concentration, allowing its integration into real-time control systems.