Impact of Spatial Distributions of Climate Condition on Building Overheating

Abstract

In this study, the spatial distribution of the urban climate is evaluated and its impact on indoor overheating conditions is assessed. This was done by modelling the near-field climate of Ottawa and Montreal at 1 km resolution for the summer of 2018 during which an extreme heat event occurred causing nearly 100 deaths in this area. The climate data obtained from Weather Research Forecasting simulations were used for assessing the extent of overheating within a prototype model of a single-detached home using EnergyPlus. The overheating conditions were evaluated using the mean temperature, the number of hours with the temperature above 28°C, and the number of hours cooling from a base temperature of 28°C. A workflow for selecting representative locations within the city for building overheating assessments was established by considering five (5) different quantiles, including 0%, 5%, 50%, 95%, and 100%, of the three calculated overheating metrics over the urban and the rural area. The degree of indoor overheating in homes was quantified and differences in overheating of homes in urban and rural settings as well as those arising within different urban areas (intra-urban) were determined. The most significant intra-urban indoor mean temperature differences of buildings at different locations were 1.8°C for Montreal and 1.6°C for Ottawa. For the number of hours with a temperature above 28°C, the intra-urban difference can be up to 829 hours for both cities. It was also found that the overheating conditions between different locations may be affected by the external air temperature and other variables, such as the local wind speed, which greatly varied the natural ventilation air change rate of buildings. The overheating conditions in buildings of different locations were also compared by analyzing the time-series variation in temperature. It was determined that there always exists a difference between the duration and intensity of indoor overheating in single-family homes of different locations.