Optimizing Natural Ventilation through Courtyard Design for Climate- Resilient Built Environments in Tropical Regions

The increasing heat stress in tropical warm-humid climates underscores the need for low-energy cooling strategies, especially in low-income and informal settlements where mechanical cooling is not economically viable. Courtyard houses have been widely used as a passive cooling technique, but poorly designed courtyards have been shown to actually contribute to increased heat gain instead of heat loss. The current study examines the effects of courtyard geometry and opening configurations on natural ventilation and thermal comfort inside buildings. Field measurements were conducted over 10 days, and CFD simulations using the RANS model were performed for 7 courtyard and opening configurations, including airflow alignments and open-to-sky exhaust strategies. The results show that the best performance was achieved with the longitudinal and bidirectional cross-ventilation and open-to-sky exhaust strategies, resulting in ambient cooling of 1.5–1.8°C, higher indoor air speeds of 0.45–0.55 m/s, reduced heat transmission, and higher thermal adaptability, as defined by ASHRAE Standard 55 for adaptive thermal comfort. In contrast, misaligned airflow paths and exhaust strategies led to recirculation and stagnation, raising temperatures above ambient. The results of this study will provide a better understanding of the airflow paths that make a poorly designed courtyard ineffective and will offer useful guidelines for using natural ventilation and open-to-sky exhaust strategies to improve thermal comfort and reduce cooling loads in tropical-climate buildings. Urban Housing Redevelopment and Gentrification of Lagos Metropolis: