Evaluation of urban form influence on pedestrians' wind comfort

Abstract

In recent decades, the pedestrian's outdoor thermal comfort has been critical for designing sustainable cities, which can be affected by wind flow in urban spaces. Urban forms influence wind speed, changing the urban air quality, and causing pedestrians' thermal comfort or discomfort. Therefore, it is required to design the urban spaces in such a way as to regulate the wind speed in order to provide thermal comfort situations for pedestrians based on their climate conditions. This study aimed to provide a framework for analysing the outdoor thermal comfort of various building layouts and their relation to wind speed in a site. This paper also proposed new indexes for improvements to the Physiological Equivalent Temperature (PET) index enabling the calculation of outdoor thermal comfort based on the likelihood of people being outside for a whole day. In-situ measurements were carried out in Tehran, Iran, to validate the presented framework. Simulations were conducted for 15 critical points in nine different building layouts for the windiest day on the site. ENVI-met was used to simulate the wind speed, outdoor air temperature, and mean radiant temperature, while PET was calculated by means of Leonardo and RayMan. The results demonstrated that pedestrians' outdoor thermal comfort for in-site and out-site points improved by 2.8% and 2.3%, respectively, compared to the current site situation. Also, the framework produced a suitable urban form to provide outdoor thermal comfort with evaluating different urban forms.