Influence of blind size on heat transfer and natural ventilation in double‐skin façades: A CFD study

The thermal performance of double‐skin façades (DSFs) is strongly affected by the design of shading devices integrated within the cavity. While previous studies have mainly focused on blind angle and position, the influence of blind slat size remains insufficiently explored, particularly under hot climate conditions. In this study, a two‐dimensional computational fluid dynamics (CFD) model, validated against experimental data, is developed to investigate airflow patterns, temperature distribution, and heat transfer within the DSF cavity. Five blind sizes ranging from 40 mm to 240 mm are analysed. The results show that increasing blind size enhances solar radiation absorption, leading to higher cavity air temperatures, with peak values reaching approximately 315.8 K. However, larger blinds significantly reduce the inner glass temperature and decrease heat transfer towards the indoor environment due to improved shading performance. In addition, the airflow structure is modified, with noticeable changes in velocity distribution and natural ventilation behaviour within the cavity. Overall, the findings highlight that blind size is a key design parameter that can improve the thermal behaviour of DSF systems and reduce heat gains in buildings located in hot climates.