Assessment of thermal comfort parameters in various car models and mitigation strategies for extreme heat-health risks in the tropical climate

Abstract

Assessing the thermal comfort of the car in a hot and humid climate is crucial as it may have adverse health implications. In the current study, different models of car were used to conduct real-time monitoring of temperature and relative humidity (RH %) inside the car cabin to assess the thermal comfort of a virtual occupant. The temperature in car cabins during the monitoring period ranged between 26.7 and 64.9 °C while the range of RH was 8.3–60.4%. Data from meteorological stations were also collected to develop a scenario of thermal comfort of occupants outside the car in standing position. The PMV range as per ASHRAE 55–2017 guidelines for ambient conditions was 3.24–7.41, the car front was 8.36–11.87, and the car back was 11.5–18.04. The thermal comfort sensation was found to be hot in all instances and followed category IV of EN15251 guidelines. PMV was observed to be worst for Sedan for both front and back as per both ASHRAE 55–2015 and EN12521 guidelines. The PPD was observed to be 100% in all cases, showing dissatisfaction for all car models. The concentration of CO2 and CO ranged between 113-1127 ppm and 0–3.9 ppm, respectively, for the front of the car. The results were also compared with the threshold values of thermal comfort parameters according to ISHRAE Standard 10,001:2016 and found to be acceptable. Climate change is leading to extremes in temperature, this may impact the thermal comfort of the car occupants to a great extent due to the heating of the car cabins, which act as a closed microenvironment. Hence, the current study urges to formulate guidelines for car design based on thermal comfort and developing a sensor to indicate thermal comfort for occupants to avoid adverse health impacts in the hot climate.