3.1 Measurement results
During the test period, the weather was good, the outdoor air temperature ranged from-1.5 to 13.9°C, with a large fluctuation range. The daily average temperature difference was about 15.4°C, and the daily average temperature was 6.3°C. The variation range of outdoor air relative humidity was 15% -70%, and the average relative humidity was 54%. The humidity fluctuation range was large and the overall change trend in one day was opposite to the outdoor temperature. As shown in Fig. 3, the temperature difference between day and night was large during the test, and the humidity was low during the day of 25 and 26. As shown in Fig. 4 (a), the influence of dormitory orientation on indoor air temperature is not obvious. This result is related to the building structure mentioned in Section 2.1. The indoor temperature is between 19-23°C and the change rule is affected by indoor personnel activities. As shown in Fig. 4 (b), the fluctuation range of indoor humidity is between 27% and 58%. In general, the trend of indoor temperature and humidity is the same, and the fluctuation of temperature and humidity is closely related to personnel activities and whether doors and windows are opened. Indoor personnel generally leave the dormitory for dinner at 7:00-8:00 am, 11:00-12:00 noon, and 17:00-18:00 pm. Personnel activities make the temperature and humidity decrease in the above three time periods. From 23:00 at night to 7:00 the next day is the sleep time. During this period, the doors and windows are closed and there is no personnel activity. The indoor temperature and humidity are on the rise due to the heat and humidity of respiration. The reasons for the increase of indoor humidity after closing doors and windows are personnel breathing, drying clothes, humidifier, etc.
3.2 Questionnaire results
3.2.1. Basic information
The subjects of this questionnaire survey were mainly undergraduates, aged between 18 and 25 years old. Among the respondents, 174 males accounted for 63 % and 103 females accounted for 37 %. As shown in Fig. 5, affected by the COVID-19 epidemic, 88% of the subjects stayed in the dormitory for more than 2 hours continuously, followed by 1-2 hours, accounting for 8%.
3.2.2 Thermal environment investigation
PMV(Predicted Mean Vote) is used as the overall evaluation index of thermal comfort, and the PMV value is based on the measured survey data and Fanger's PMV equation. The relationship curves of MTS (Mean Thermal Sensation Vote) and PMV with air temperature were drawn respectively. As shown in Fig. 6, the actual thermal sensation TSV of the subjects was closer to thermal neutrality than the PMV prediction results. The linear regression equations of MTS and PMV were obtained by weighted regression analysis of MTS, PMV and air temperature. The fitting degree of MTS and PMV with air temperature was very high (MTS: R2 = 0.977, PMV: R2 = 0.938). The measured thermal neutral temperature (MTS = 0) is 21.68°C, and the predicted thermal neutral temperature (PMV = 0) is 21.81°C.
The method of taking the average of the same votes was used to average the thermal comfort values corresponding to the same thermal sensation vote, and the thermal comfort values corresponding to each scale of thermal sensation vote were obtained. The binomial fitting formula was as follows :
![](https://myfiles.space/user_files/122228_c8a1650c59388082/122228_custom_files/img1686142824.png)
Where TCV is thermal comfort vote ,TSV is thermal sensation vote and R2 is goodness of fit.
It could be seen from formula (1) that R2 was 0.99, and the fitting degree of thermal sensation vote and thermal comfort vote was very high. The fitting curve was shown in Fig. 7. As the TSV value increases, the TCV value increases first and then decreases, showing a parabolic shape with a downward opening. When TSV value was -3 (very cold), TCV value was -2 (very uncomfortable), while when TSV value was 3 (very hot), TCV value was -1 (uncomfortable). When TSV value was -2 (cold), TCV value was -1 (uncomfortable), while when TSV value was 2 (hot), TCV value was about 0 (comfortable). This shows that during the test, the comfort of the subjects in the hot environment was higher than that in the cold environment, and they were more inclined to the hot environment.
3.2.3 Air quality investigation
The importance of ventilation has been widely emphasized during the COVID-19 pandemic[39]. Studies have suggested “appropriate” ventilation as a measure to reduce the possible airborne spread of SARS-CoV-2[40].The survey results of indoor air quality satisfaction in this study were shown in Fig. 8. 59% of the subjects thought that indoor air quality were "acceptable", 9% thought that "satisfied", and 26% were "dissatisfied". 6% of the subjects felt "very dissatisfied", while no one felt "very satisfied". In general, more people were dissatisfied with indoor air quality. As shown in Figs. 9 and 10, 37.4% of the subjects only opened doors and windows when they felt uncomfortable, and 2% never opened windows. 59% of the subjects chose to open a part of the door and window, 6% left a small gap, and 2% closed all. This shows that most people didn’t fully realize that indoor air quality could be adjusted through adaptive behavior, such as intermittent opening of doors and windows, increasing the opening of doors and windows.
3.2.4 Emotional investigation
In this epidemic, the emotions of college students have been greatly affected[41], especially considering the implementation of school closure and quarantine measures. As shown in Fig. 11, 67% of the subjects' emotional state during the quarantine period was "Quiet", followed by "Spirited", accounting for 18%, "Low-spirited " accounting for 12%, and “Restless” accounting for 3 % . In general, most students were in a "Quiet" state of mind during the period of quarantine. The proportion of students in good mental state and those in poor mental state was close to and small. As the investigation period was in the early stage of lockdown and quarantine, the quarantine time was relatively short. Although students with poor mental state had appeared, they account for relatively few.
3.2.5 Activity state
As shown in Fig. 12, 4% of the subjects' activity status was "Training", and the proportion of "going downstairs" was 3%. It can be seen from Table 3 that “Training” is a medium-intensity activity, “going downstairs” is a high-intensity activity, and other activities in Figure 12 are low-intensity and no-intensity. In general, the activity intensity of the subjects was small, which was due to the long residence time in the room during the epidemic, and the indoor environment of the dormitory had the characteristics of small space and high personnel density, which was not convenient for high-intensity activities.