A Novel Approach to Assessing Residential Overheating Health Risks during Heatwaves in Guangzhou

Indoor overheating during extreme heat waves events is a major concern to human health, particularly for people vulnerable to prolonged exposure to hot and humid climate without access to air conditioning. However, Current methods for assessing indoor overheating risk lack a balance between complexity and practicality, either relying on intricate indicators or oversimplifying assessments, compromising accuracy and applicability. This paper developed a new evaluation method for indoor overheating risk that is based on the heat-related health of occupants but using only simple environmental parameters as metrics. Firstly, an analysis was conducted on the indoor thermal environment that residents may experience during heatwave events compounded with power outages in Guangzhou, a typical city in hot and humid climate. Subsequently, incorporating the human thermal regulation model - JOS-3, the physiological parameters of residents during such events were computed. Finally, sensitivity analysis was employed to identify the most influential factors, and the metrics and thresholds for indoor overheating were determined based on limits for body water loss rate and core temperature of healthy young adults and elderly individuals. The results showed that heat index hazard hours (HIHH₂₇) and maximum heat index HI_max can be utilized to evaluate the severity and intensity of indoor overheating during heatwaves in hot and humid areas respectively. When HIHH₂₇ exceeds 1174°C·h (850°C·h) or HI_max approaches 55°C in buildings occupied by young adults (elderly), serious indoor overheating incidents occur, posing a significant heat risk to occupant.