Thermal environment and thermal comfort in metro systems: A case study in severe cold region of China

The urban rail transit in China has been booming, and improving the comfort of the riding environment is critical to ensuring its long-term development. However, few studies have investigated thermal comfort in metro systems in severe cold regions; moreover, there is a lack of data to support metro-related specifications. This study adopts a whole-process thermal comfort tracking method for investigating passengers' thermal responses and moni-toring thermal environment during entering, riding, and leaving metro stations. Field studies are carried out in summer of 2018 and 2019 on two metro lines in Changchun, a typical city in severe cold regions of China. A total of 717 valid samples are obtained. The results show that thermal environment in metro systems is non-constant in spatial dimension. The overall thermal sensation in metro systems is slightly cool, and there is little cooling need in carriages, which can potentially save energy. The thermal comfort zone is obtained based on the acceptable temperature and humidity ranges for 80% of passengers. The comfort zone satisfies the Chinese code, and except for the platform is approximately 0.8-1.6 degrees C wider than that specified in ASHRAE 55-2017. Despite high humidity levels (up to 86.2%) in metro system, passengers feel comfortable at temperatures up to 24.7 degrees C. Meanwhile, the thermal comfort zone does not fall exactly within the air velocity range specified by ASHRAE 55-2017. This research provides valuable references for improving comfort specifications and environmental control in metro systems in severe cold regions.

Automated summary

This study adopts a whole-process thermal comfort tracking method to investigate passengers' thermal responses and monitor the thermal environment in metro systems. The results show that the thermal environment in metro systems is non-constant in spatial dimension, and the overall thermal sensation is slightly cool. The research provides valuable references for improving comfort specifications and environmental control in metro systems in severe cold regions.