Prediction of the indoor carbon dioxide concentration in the central library using an ODE model

Name: Thaisin Iwaki

Organization : Chulalongkorn University. Faculty of Engineering

Name: Nawin Nateenantasawasd

Organization : Chulalongkorn University. Faculty of Engineering

Name: Pisit Pongsaran

Organization : Chulalongkorn University. Faculty of Engineering

Name: Chittin Tangthieng

Organization : Chulalongkorn University. Faculty of Engineering

LCSH: Carbon dioxide -- Measurement

LCSH: Indoor air quality

LCSH: Libraries -- Environmental conditions

LCSH: Mathematical models

LCSH: Building environment -- Modeling

Abstract: The central library is one of the main academic facilities inside Chulalongkorn university for supporting learning, research, and recreation. During the exams preparation period, in which the building operates 24 hours daily, the number of occupants in the library is relatively high, resulting in the elevated CO2 concentration level. Although the elevated level of the CO2 concentration are not lethal, it can influence productivity levels and correlates with an increase in sick building syndrome symptoms. This project aims to determine solutions and methods to reduce the indoor CO2 concentration on the second floor of the library with the high occupancy level. Various data related to the building HVAC system were obtained from the building automation system and from the direct measurement. A CO2 concentration model was developed through the ordinary differential equation model based on the mass balance equations of the air flow and the CO2 concentration. The model is used to predict the variation of the CO2 concentration on the second floor and to estimate the CO2 concentration reduction from two selected implement measures. The fourth order Runge-Kutta method is applied to solve the ODE for the numerical solutions. The comparison between the field measurement and the ODE is made with good qualitative agreement. The cyclic behavior of the CO2 concentration during the 13 day peak period of the library is observed. The CO2 concentration will follow the similar pattern to the number of occupants with the delay effect of 3 hours. By increasing the ventilation rate on the second floor as the first implement measure, the results indicate that CO2 concentration can be reduced to the satisfied level of 1,050 ppm with the ventilation rate to approximately 9,227.6 m3/hr for 15 hours per day. The second implement measure is to impose an occupancy limit of 160 people on the second floor in order to achieve the satisfied level of CO2 concentration.

King Mongkut's University of Technology North Bangkok. Central Library

Address: BANGKOK

Email: library@kmutnb.ac.th

Created: 2024

Modified: 2025-08-19

Issued: 2025-08-19

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BibliograpyCitation : In Thai Society of Mechanical Engineers (TSME) and Kasetsart University (KU). The 14th TSME International Conference on Mechanical Engineering (TSME-ICoME14 2024) (TSF0001). Chonburi : Kasetsart University Sriracha Campus, 2024

eng

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