Determination of Optimal Placement of Indoor CO2 Sensors Using Computational Fluid Dynamics

Abstract: Indoor air quality (IAQ) is an important factor in ensuring that indoor environments such as the workplace, home, places of leisure, do not lead to reduced productivity, comfort, or sickness. Maintaining good indoor air quality begins with assessing contaminant concentrations with carbon dioxide being the norm as an indicator of IAQ. Accuracy of IAQ measurements may be achieved through placing multiple sensors throughout a room but this comes with a cost. This may be remedied by analyzing the optimal placement of a single sensor to accurately represent the mean concentration within a room, with probable indication of the distribution within the same room. Computational Fluid Dynamics (CFD) offers a numerical method to determine this optimal location along with a probable distribution of carbon dioxide relative to known emission sources and locations of ventilation. The present study aims to develop a verified and validated carbon dioxide dispersion model within a fan-ventilated bedroom, then apply the model to investigate the impact of room geometry and ventilation on indoor air quality. Validation against experimental data yields root mean square errors of 0.26 m/s and 22.09 ppm for airflow and CO2 concentration, respectively. Results indicate that mechanical ventilation effectively homogenized the CO2 concentration within the room, with no signs of vertical stratification. Approximately 97.1% of the room's volume exhibits carbon dioxide concentrations within +-10 ppm of the mean concentration. Keywords: indoor air quality, carbon dioxide, CFD, species transport