ENHANCING INDOOR AIR QUALITY THROUGH NATURAL VENTILATION: INSIGHTS FROM MUNICIPAL BUILDING IN MOSTOLES, SPAIN

This study evaluates the effectiveness of natural ventilation in enhancing indoor air quality within the Almudena Grandes Central Library, a municipal building in Móstoles, Spain. Triggered by the public health challenges highlighted during the SARS-CoV-2 pandemic, the research develops a methodological framework that integrates CO2 monitoring, occupancy modeling, and airflow calculations to assess air renewal capacities under natural ventilation conditions. The analysis reveals that cross ventilation is the only strategy capable of achieving IDA 2 air quality standards in high-occupancy areas, requiring at least five air changes per hour. Zenithal openings, such as roof ventilators, significantly enhance airflow during colder months with strong indoor-outdoor thermal differentials, even when external wind is minimal—a frequent scenario in continental Spanish climates. The study also explores buoyancy and wind-driven ventilation mechanisms and quantifies their respective contributions using empirical models. Results suggest that the library can maintain acceptable air quality for up to 310 users with sufficient cross-ventilation measures. However, single-sided ventilation proves inadequate. The proposed model supports dynamic capacity management and energy efficiency by integrating real-time environmental data. The authors highlight the potential of automating ventilation systems via domotics for continuous air quality monitoring and optimization. Limitations include the variability of outdoor conditions and the need for future validation using Computational Fluid Dynamics (CFD) and additional case studies. Overall, the findings emphasize architectural strategies as pivotal in promoting healthier, energy-efficient indoor environments in public infrastructure. Key Words: cross ventilation, indoor air quality, natural ventilation, infection risk reduction, occupant load estimation