Sky Access versus Shading for Pedestrian Comfort in the Hot Tropical Climate of Jeddah

Many urban studies have been done to demonstrate that urban sprawl is not the right approach in hot climate cities. On the contrary, a compact design is recommended to enhance human thermal comfort. This research aims to clarify the relation between urban morphology and outdoor thermal comfort of Jeddah, Saudi Arabia. The aim is to develop an outstanding future strategic compact morphology that would facilitate a dynamic development of the city. Jeddah city will soon have a subway that is expected to radically change the habits of its inhabitants. Our idea is to consider the main stations of the future metro as nodes, creating more densely inhabited localities and also defining transitional spaces for pedestrian activities. Microclimates generated in and around these activity nodes must be particularly studied to encourage residents and visitors to reclaim a pedestrian life that was clearly noticeable in the old city, but has virtually disappeared in most recent neighborhoods, entirely devoted to automobile transport. Services and facilities around metro nodes should become the transitional thermal comfort areas of the metro station exits. This paper will provide numerical modeling simulations that are used to assess the solar radiation in the urban layout (the old compact area and the modern sprawl area) by the software "Heliodon 2" (direct shortwave, Sky View Factor) and "Heliodon plus" (climatic data) to clarify the differences between the old and the new layout and why the change to compactness needs to be put into effect.