Overheating analysis of optimized nearly Zero-Energy dwelling during current and future heatwaves coincided with cooling system outage

It is expected that heatwaves will strike more frequently and with higher temperatures with the contin-uation of global warming. More extreme heatwaves concurrent with disruptions in the cooling system can lead to significant overheating problems in buildings affecting occupants' health, productivity, and comfort. This paper projects current and future heatwaves on an optimized nearly Zero-Energy terraced dwelling in Brussels, assuming the outage of the cooling system. Initially, a multi-objective optimization is performed considering 13 passive design strategies using the Genetic Algorithm (GA) based on the Non-dominated Sorting Genetic Algorithm 2 (NSGA-II) method. It is found that high ventilation rate, low infiltration rate, high insulation, high thermal mass, integration of green roof, and application of operable roller blinds are beneficial in reducing the final HVAC energy use up to 32% and enhancing ther-mal comfort up to 46%. Subsequently, three optimal solutions are selected and analyzed under the high-est maximal temperature heatwaves detected during the 2001-2020, 2041-2060, and 2081-2100 periods. It is found that non of the optimal solutions are able to fully suppress overheating during heat-waves and the cooling system outage. The indoor operative temperatures reach more than 29 degrees C; which can cause serious health issues for the occupants. The situation will be exacerbated in the future since an increase in maximum Heat Index (HI) between 0.28 degrees C and 0.49 degrees C, an increase in the maximum operative temperature between 1.34 degrees C and 2.33 degrees C, and a decrease in Thermal Autonomy (TA) between 17% and 28% are estimated. Finally, some recommendations are provided for practice and future research.(c) 2023 Elsevier B.V. All rights reserved.