Study of Urban Building Configuration Impacts on Outdoor Thermal Comfort Under Summer Heatwave via CityFFD and CityBEM

In the past decades, summer heatwaves are becoming more frequent and creating a major concern about their impacts on human health. Predicting outdoor thermal comfort during summer heatwaves is thus essential to help avoid economic and life losses. Existing research often investigates urban outdoor thermal comfort via CFD (computational fluid dynamics) modeling and indoor overheating conditions by BES (building energy simulations). However, modeling a large urban area under transient weather would require extensive computational costs and detailed building information settings. In the present work, a novel method coupling the CityFFD (City Fast Fluid Dynamics) and CityBEM (City Building Energy Model) is utilized to predict the air temperature distribution in three different urban areas during a summer heatwave in Montreal, Canada. The numerical model is well validated with onsite measurement data of the heatwave from July 15 to July 16, 2013. Based on the air temperature profile at the pedestrian level, the outdoor thermal comfort, and its impact were evaluated via Humidex. The results are also compared with the predicted urban thermal environment by Environment Canada. This paper shows that urban configurations may significantly affect the thermal risk during the summertime heatwave, and the proposed integrated model can estimate urban microclimate with details for urban overheating assessment.