Due to climate change effects, summer outdoor temperatures are rising. Such climatic changes may result in overheating the interior spaces of buildings, and thus potentially lead to health issues for building occupants such as heat exhaustion, dehydration, heat strokes and even mortality. Overheating effects were investigated for residential buildings using EnergyPlus (R) as a simulation tool. To capture the thermal comfort and behaviour of building occupants, the EnergyPlus (R) object Air Flow Network was utilized. Moreover, residential units were split to two zones: day (living room) and night (bedroom). We generated three models for residential building archetypes. The effectiveness of several passive cooling strategies, such as shading, ventilation, various glazing types, and thermal mass, were evaluated for the historical climate, and future projected climate data of Ottawa, Canada. The results showed that during outdoor extreme heat events, the most effective passive measures are the use of exterior shading of building fenestration and to increase night-time ventilation to the building