Thermal comfort condition of passengers in naturally ventilated train stations

Train is the most frequently used means of transportation in Tokyo. Train stations are gaining attention as commercial complex today, and higher level of comfort is being demanded for the indoor environment. Open structure of the train station and semi-outdoor like environment suggest that the thermal comfort condition is relaxed compared to indoor comfort standards. The objective of this study is to investigate the thermal comfort condition within train stations and to clarify the appropriate target for environmental control. Field surveys were carried out in summer, autumn and winter during July 2004 to August 2006 in four train stations located in urban area of Tokyo. Concourses were not air-conditioned except one station where spot cooling was operated in summer near the ticket gate. Each survey was conducted from 7:00 to 20:00 for 3 to 11 days per season per station for a total of 81 days. The survey consisted of thermal environment measurement and thermal comfort questionnaire. More than 80% of passengers felt thermally comfortable within the range of 19 to 29 °C SET*. However, acceptability zone was found to be 19 to 32 °C SET*, and it is recommended to design naturally ventilated train stations to fulfil this target.