Abstract
It is recognized that ambient air temperatures (T-a) inside urban cores are higher than that in their rural surroundings, forming what is known as the urban heat island (UHI) phenomenon. During the summer in hot and dry regions, the UHI intensity is significantly influenced by the extreme direct solar radiation and leads to outdoor thermal discomfort during the entire day. The present study aims to investigate the thermal performance of three different urban configurations and street geometries in the metropolitan city of Baghdad, Iraq: traditional compact, modern attached, and modern detached. To ensure that the urban configuration is the only factor for comparison, vegetation was excluded and materials for buildings and streets were unified in all examined study cases. The evaluation of the ambient air temperature (T-a), street surface temperature (T-s) inside the urban canyon, and mean radiant temperature (T-mrt) was conducted by utilizing the three-dimensional numerical software Envi-met 4.0. The three variables T-a, T-s, and T-mrt were measured at the center of the street in each urban configuration. The investigation of this study has provided a better understanding of the role of urban form configurations in forming the UHI that affect the microclimate in hot and dry regions, which has therefore helped to generate guidelines of urban design and planning practices for a better thermal performance in cities. In particular, the study has contributed to the validation of the impacts of urban canyons on the temperature variations in built environment. (C) 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.