A practical approach to the evaluation of local urban overheating– A coastal city case-study

Abstract In response to urbanization and global warming, which amplify heatwave effects and might lead to urban heat stress, this paper proposes a practical approach to characterize the local microclimate at the neighborhood scale. In this approach, the local urban climate is described using suitable indicators, to support the ecodistrict design process or refurbishment. Experimental and numerical results illustrate the approach in a case study of a French coastal city, La Rochelle. In the first step, we set up urban and rural weather stations to characterize the local urban climate over a summer period and to identify local temperature differences. The measurements highlighted a daytime urban cooling effect due to the local sea breeze. While the Urban Weather Generator (UWG) simulation tool used for this study does not capture coastal effects, the results were consistent with the urban heat island (UHI) measurements. We proposed two indicators to quantify the local climate modifications: local UHI and overheating intensity. The parameters of the adaptation strategies were assessed through a sensitivity analysis for these two indicators. For this case-study, we identified vegetation cover, building height and road albedo as key parameters that can be used to mitigate local overheating.