Evaluation of the Thermal Environment of Xi’an Subway Stations in Summer and Determination of the Indoor Air Design Temperature for Air-Conditioning

Abstract

Taking two typical subway stations in Xi’an as the research objects, the thermal environment and human thermal comfort of the station in summer were studied based on field measurements and a questionnaire survey. Based on the relative warmth index (RWI), the passengers’ thermal comfort during the process from entering to leaving the station under the operating temperature and the designed temperature was also analyzed. Moreover, the RWI method was modified based on the comparative analysis of the predicted results from the RWI and questionnaire methods. Then based on the revised RWI method, the suitable indoor air design temperature in Xi’an subway stations was discussed. The research results revealed that if the air-conditioning system was operated at the design temperature suggested by Code GB 50157-2013, it cannot meet the thermal comfort needs of most passengers. Only when the temperature of the platform was at least 1 °C lower than that in the station hall did the passengers obtain temporary relative thermal comfort. According to the control proportion that 25% of passengers need a cooler environment, the indoor air design temperature for air-conditioning in Xi’an subway stations should be 25.5 °C in the station hall and 24.5 °C on the platform.