Ventilation characteristics of buildings incorporating different configurations of curved roofs and wind catchers: (with reference to human comfort)

This study investigates the effect of utilising different configurations of curved roofs and wind catchers on natural ventilation performance of buildings. It compares airflow rates and internal airflow velocity and distribution, before and after, employing domed and vaulted roofs for wind-induced natural ventilation and, thus, thermal comfort improvement. This also includes the role of integrating different wind-catcher systems into the investigated curved roofs. A review of the related background studies and literature has revealed the architectural importance of these elements, and their potential for natural ventilation and passive cooling in hot climates, with particular reference to the Middle East. A review of the different natural ventilation prediction methods has also exposed the challenge associated with air infiltration modelling and understanding. Computational Fluid Dynamics (CFD) simulation, using Fluent 5.5 software, has been used as a main research tool. The code used has been validated based on a comparison between airflow rate estimated using Fluent 5.5 software, and airflow rate estimated using the Network mathematical model. This ensures the reliability of the natural ventilation performance assessment carried out. A parametric approach has been adopted to establish a systematic comparison between the effects of the different geometrical and climatic parameters considered, with a reasonable variety that fit the study limits. This included a summarised thermal comfort assessment, implementing the Tropical Summer Index (TSI), developed by Sharma and Ali (1986). The comparison showed that the use of the curved roofs and wind catchers for natural ventilation leads to a significant improvement in natural ventilation of the indoor space, presented as a reformation of internal airflow paths, and a reduction of the area of the still-air zone by about 20%. This increases the average indoor velocity, and improves thermal comfort conditions inside the building, depending on the outdoor climatic conditions. This has been found to be more critical under less favourable wind conditions, as in the case of deep-plan buildings. The results obtained in this study have been used to formulate design guidelines, which progress the understanding of airflow behaviour inside and around buildings incorporating different combinations of curved roofs and wind catchers. This is a new contribution to the research efforts carried out in the field of sustainable architectural design