Natural Ventilation: Optimizing Window Opening Size for CO2 Concentration Control and Thermal Comfort on Nonwindward Facades

Natural ventilation has become a focal point due to its positive impact on indoor air quality, expanding its role in addressing thermal comfort issues in schools. Despite previous studies exploring various approaches to enhance natural ventilation, factors such as classrooms facing non-windward directions and optimal window opening sizes have not been adequately considered. This lack of consideration poses challenges for implementation in school environments. To address this issue, this study employed response surface methodology, back-propagation neural network, and multiple linear regression to investigate the effects of different factors on natural ventilation. Experiments were conducted in classrooms facing nonwindward directions, measuring indoor air changes per hour (ACH) during peak noon temperatures. Thermal comfort was assessed using the predicted mean vote (PMV). The experimental results showed that single window openings provided better thermal comfort compared to cross window openings while maintaining indoor CO2 concentrations below 1000 ppm. Furthermore, subsequent analysis revealed that the opening size (open and open/gap) increases the range of ACH, suggesting avenues for future research to enhance natural ventilation practices. This underscores natural ventilation’s potential in maintaining indoor thermal comfort and CO2 levels under challenging conditions.