Optimising Mechanical Ventilation for Indoor Air Quality and Thermal Comfort in a Mediterranean School Building

The growing concern over indoor air quality (IAQ) and thermal comfort in classrooms, especially post-COVID-19, underscores the critical need for optimal ventilation systems to bolster students' health and academic performance. This study explores the potential for improving indoor air quality and thermal comfort in the most energy- and cost-optimal manner using a demand-controlled ventilation (DCV) system coupled with a carbon dioxide control sensor. This is achieved through precooling via night purging in summer and by introducing warmer corridor air into the classroom in winter. The methodology employs both computer simulation and a real-world case study. The findings reveal that while natural ventilation in winter can achieve IAQ standard (EN 16798-1) thresholds for classrooms under favourable outdoor conditions, it results in uncontrolled and excessive energy loss. The retrofitted DCV system, however, maintained CO2 levels below the recommended thresholds for at least 76% of the year depending on classroom orientation and only exceeded 1000 ppm for a maximum of 6% of the year. This study also indicates that utilising the external corridor as a sunspace can further enhance the system's efficiency by preheating incoming air. This comprehensive study highlights the significant potential for integrating mechanical and passive solutions in school ventilation systems. This contributes to the attainment of the United Nations Sustainable Development Goal 11 and ensures healthier and more energy-efficient learning environments that benefit both students and the environment.