Assessing the impact of natural ventilation on indoor air quality in residential buildings: A Case Study in Dhaka

This research investigates the impact of natural ventilation on indoor air quality (IAQ) in residential buildings in Dhaka, focusing on the concentration of formaldehyde (HCHO) and volatile organic compounds (VOCs), particularly toluene. Utilizing an experimental-comparative approach, the study measures IAQ under two ventilation conditions: "Natural Ventilation OPEN" (windows, balcony doors, and exhaust systems operational) and "Natural Ventilation CLOSE" (sealed indoor environment). Data was collected across 12 sessions over three months (May to July 2024), using IAQ Process Test Methods prescribed by the World Health Organization (WHO). Measurements included temperature, humidity, formaldehyde, and toluene concentrations in living rooms and adjacent balconies. Results revealed that natural ventilation significantly improved IAQ, with pollutant concentrations reduced by approximately 40% during the summer months. However, variations in ventilation rates (0.3–0.8 times/h) did not significantly affect IAQ, suggesting that external environmental factors, such as outdoor air quality and seasonal changes, played a more critical role. The study also analyzed the effects of different ventilation configurations, including supply/exhaust duct systems and heat exchanger types. While all systems demonstrated moderate improvements in IAQ, natural ventilation was the most effective in reducing pollutant levels, particularly formaldehyde and toluene. This research highlights the importance of natural ventilation in mitigating indoor air pollution in Dhaka's tropical climate. However, unexpected spikes in pollutant levels and minimal differences across ventilation systems suggest the need for further investigation into alternative strategies, building materials, and environmental conditions to optimize IAQ. These findings provide valuable guidance for architects, policymakers, and residents in designing healthier, energy-efficient residential buildings while addressing IAQ challenges in urban settings