Green building design strategies have been adapted, studied, and improved for decades around the world. In Taiwan, there are many buildings that have been certified based on the green building rating system, EEWH. Among these buildings, an elevated transportation facility was rapidly constructed and certified. Furthermore, to reduce energy consumption, most of the EEWH certified elevated transportation facilities in Taiwan incorporated natural ventilation by using an open curtain wall system as the passive design strategy. However, as Taiwan has a humid and hot climate, the use of natural ventilation to cool a space and create the optimal thermal comfort condition is a difficult method to design. Thus, this study focuses on understanding the actual thermal comfort quality of the elevated station that uses the natural ventilation design method.
Zhongshan Junior High School metro rapid transportation (MRT) station of Wenhu Line in Taipei was selected and studied for the appropriateness of using natural ventilation with a semi-open curtain wall system. Climate Consultant was first used to derive the psychrometric chart to understand the climate of the site. The chart indicates that natural ventilation is not recommended due to the high temperature and relative humidity condition. Onsite measurements with an aerometer for wind speeds, temperature and humidity were performed in March and April. The measurement results were then entered in the CBE thermal comfort tool with walking and standing as metabolic rates to determine whether passengers will have thermal sensations that comply with ASHRAE standard 55. The results indicate that with current design, even in the most comfortable season in Taiwan, the thermal conditions vary and do not comply with ASHRAE standard 55. Thus, to study the effectiveness of wind flow in this station, Autodesk Flow Design was used. As Taipei has an east prevailing wind, the existing station with north–south orientation and nearby high-rise buildings do not have the optimal wind flow to disperse the humidity and evaporation of body heat. Thus, the later installed air conditioners (ACs) and ceiling fans around the ticketing area and center platforms indicate that the thermal comfort condition of this station needs to be improved. It is also critical to note that these cooling devices were not specified in the original design. The reason for the improvement could be to reduce energy demands while supporting the usage of natural ventilation with a semi open curtain wall system. Thus, calculations for the cooling and heating load of the station with or without the semi open curtain wall system have been performed in this work. In addition, energy consumption calculations with reduced window area and closed curtain wall system as well as underflow distribution use as the HVAC system for cooling were also performed. The results showed that total energy usage intensity with the modified design method can be reduced from 1079 to 1044 MJ/sm/yr. Thus, by introducing a reduced window area, a closed curtain wall system, and a HVAC system in the design method, less energy could be used than natural ventilation while providing thermal comfort.

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