## 3 Results and Discussion
### Field Survey Results and Analysis
#### 3.2.2 Occupancy satisfaction survey results and analysis  
The subjective occupancy survey was comprised of two parts: on-site questionnaires and on-site interviews. The subjective questionnaire adopted a 7-point scale, where \(-3\) corresponded with \"Very Dissatisfied\", 3 referred to the respondent being \"Very Satisfied\", and 0 was neutral (as shown in Table 10). The subjective questionnaire was issued at each test point (tp1 to tp14), 40 copies each, for a total of 560 copies. There was a total of 551 valid questionnaires completed, for a recovery rate of 98%. The test period was selected to be the same as the physical environment test, the highest temperature  
Figure 13: Comparison curves of hourly particulate matter 2.5 (PM2.5)/PM10 concentration data for each point during the monitoring day. period for the Beijing area, from 28 June 2017, to 20 July 2017. The purpose of this research was to investigate the performance of the tubular space in terms of occupancy satisfaction under the most unfavorable conditions in the summer climate. In addition, the survey also included on-site interviews. Researchers talked with subway staff, retail traders, security guards, cleaners, and passers-by for a substantial period of time. Table 11 shows the average data collected from the questionnaire. Corresponding with the analysis of the physical environment test results, this research also classified the 14 test points according to their location. There were a total of four types: middle tubular space, tube entrance (connection to building), tube entrance (connection to subway), and station hall. Based on a histogram analysis of Figure 15, the researchers found that occupants had higher levels of satisfaction in the middle tubular space, and most of the collected data were positive. The problems with higher temperatures and poor lighting were clear in the physical environment test, but the subjective feelings of the users were not obvious. However, in terms of humidity, both the subjective questionnaire and the interviews reflected the occupants' discomfort. The satisfaction results at the tube entrance (connection to building) fell into two categories. The first type was in relation to where the tube entrance connected the building to the outdoor space (tp3 and tp7). All indexes of satisfaction were low, especially in terms of thermal comfort, humidity, \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Occupancy** & **Very Dissatisfied** & **Neutral** & **Very Satisfied** \\ \hline Thermal comfort & & & & & & & \\ \hline Humidity & & & & & & & \\ \hline Air quality & & & & & & & \\ \hline Lighting & & & & & & & \\ \hline Ventilation & \(-3\) & \(-2\) & \(-1\) & \(0\) & \(1\) & \(2\) & \(3\) \\ \hline Ease of use & & & & & & & & \\ \hline Cleanliness and & & & & & & & \\ maintenance & & & & & & & \\ \hline Overall & & & & & & & \\ environmental & & & & & & & \\ quality satisfaction & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Questionnaire for the occupancy satisfaction survey. Figure 14: Wind speed curve for one operating cycle of a train. (**a**) Test point location; (**b**) Curve line. air quality, and convenience. The other type related to where the tube entrance connected to the underground building (tp14), which demonstrated positive advantages for all indicators. The most complaints from occupants were from the area near the subway. Both the space entrance near the subway and the subway platform level received lower occupancy satisfaction scores. The average thermal comfort of the tube entrance space near the subway was \(-1.85\), the humidity score was \(-1.48\), and air velocity comfort score was \(-1.38\). Compared with the physical environment test results, the thermal environment of the tube entrance space near the subway had the greatest influence on the physiology and psychology of the human body. It was also the weakest point of the inner tubular space.