The impact of building geometry on airflow and thermal comfort in urban open spaces: A case study of kashan in a hot and dry climate

• Urban building geometry greatly influences natural wind flow in hot, dry climates. • Wind tunnel tests assessed effects of building height, coverage, and orientation. • Aligning streets with prevailing winds helps preserve natural airflow efficiency. • Thermal comfort is acceptable most months and can improve with urban design. • Results offer design guidelines for sustainable planning in desert cities. Urban open spaces are essential components of the urban fabric; however, buildings situated within these areas often disrupt and reduce the natural flow of fresh air. In cities with hot and dry climates (such as Kashan) natural wind flow plays a critical role in improving outdoor thermal comfort and enhancing the overall quality of urban life. Building geometry functions as a passive design strategy that directly influences airflow, microclimatic conditions, and urban morphology. This study investigates the effects of urban-scale design elements, focusing on newly developed neighborhoods planned in accordance with the city's master plan. Specifically, it examines how variations in building geometry (the number of floors, building occupancy ratio, and orientation) affect wind flow patterns, natural ventilation, and thermal comfort in outdoor urban spaces. To achieve this, a series of controlled wind tunnel experiments were conducted using precise instrumentation to isolate and evaluate the individual impact of each parameter at both building and neighborhood scales. Results reveal that acceptable wind comfort conditions prevail for seven months of the year, while one month exhibits discomfort and three months show semi-comfortable conditions that could be improved through design modifications. Furthermore, the findings indicate that increasing the number of floors (up to six) and the occupancy ratio (up to 80 %) does not substantially reduce wind velocity. In contrast, the orientation of buildings (particularly aligning streets with the prevailing wind direction) has a significant influence on preserving and enhancing natural airflow within the urban context.