Effect of window openings on indoor air quality and CO₂ concentration in classrooms: A Case Study of Primary School, Dhaka

Abstract. This study investigates the impact of window openings on indoor air quality (IAQ) and CO₂ levels in school classrooms in Dhaka, focusing on natural ventilation strategies to improve the learning environment. The importance of effective window design in controlling CO₂ concentrations and enhancing ventilation is critical, particularly in tropical climates like Dhaka's, where indoor air quality is often compromised due to inadequate ventilation. The study aims to explore the effect of window size and ventilation on CO₂ levels, comparing classrooms with different window configurations to identify the best strategies for improving IAQ. Over a period of two measurement campaigns, the study monitored CO₂ levels, indoor temperature, and relative humidity in two elementary schools, revealing that limited window openings, particularly when windows were 75% closed, resulted in significantly higher CO₂ concentrations. The analysis showed a direct correlation between reduced ventilation and increased CO₂ levels, with concentrations peaking at 2560 ppm, well above the recommended threshold of 1000 ppm. Factors like room design, occupancy density, and window placement contributed to variations in CO₂ levels across classrooms. The study emphasizes the need for optimized window openings to promote natural ventilation and reduce CO₂ concentrations, suggesting that opening windows beyond 50% can significantly improve IAQ. Regular monitoring, maintenance, and the implementation of effective ventilation strategies are essential to maintaining healthy indoor air quality in schools, ensuring a conducive learning environment for students. This research highlights the critical role of building design and ventilation systems in enhancing IAQ in educational settings.