Field investigation on thermal comfort of metro passengers in hot summer and warm winter zone of China: A case study in Guangzhou

In the hot summer and warm winter zone of China, the metro thermal environments and passengers' thermal comfort were rarely examined, influencing factors such as commuter hours and individual factors were less discussed, and understanding them was beneficial for improving human thermal comfort and saving energy. In this study, a field study was undertaken in Guangzhou located in the region during the summer of 2023. Four metro stations and three metro lines were selected, a total of 1481 valid questionnaires were gathered. The results revealed that the metro thermal environment was highly commendable during the hot summer months, with a thermal acceptability vote (TAV) ranging from 81 % to 89 % across the entrance (ET), concourse (CC), platform (PF), and carriage (CR). Furthermore, the upper limit of the 80 % acceptance range for operative temperature (T-op) was 29.11 degrees C in the ET, 27.82 degrees C in the CC, 29.13 degrees C in the PF, and 28.44 degrees C in the CR. These temperatures exceed the actual mean T-op values in these locations, indicating there is a significant potential for energy savings in metro environments. The upper limits of T-op values for passengers with low, medium and high metabolic rates are 30.34 degrees C, 28.92 degrees C, and 28.25 degrees C, respectively. Thermal sensation votes (TSVs) fell well within the comfort zone specified in ISO 7730 (-0.7 < PMV < 0.7) during both peak and off-peak hours. No difference was found in TSVs between the two genders and among the different ages.