# Differences Research on Human Overall Comfort Under Low Pressure
## 4 Discussion
### Differences Analysis in Human Overall Comfort Evaluation Under Low Pressure
#### 4.3.1 The Influence of the Factor Unit Changes on the Overall Comfort  
1. Operative temperature influence on \(\mathrm{POCV_{L}}\)  
Taking the winter conditions as an example, the influence of operative temperature on the overall comfort evaluation was analyzed under low pressure. When the atmospheric pressure decreased, Figure 10 showed that the \(\mathrm{POCV_{L}}\) variation trend was the same as that under standard atmospheric pressure [52]. Taking \(t_{0}=22.4\,^{\circ}\mathrm{C}\) as the center, when the temperature increased or decreased, the changes in \(\mathrm{POCV_{L}}\) gradually increased. Under \begin{table}
\begin{tabular}{c c c} \hline \hline
**Pressure (kPa)** & **Comfort Level** & **Noise (dB)** \\ \hline
101 & I & \(\leq\)64.0 \\
101 & II & \(\leq\)69.0 \\
80 & I & \(\leq\)64.8 \\
21 & II & \(\leq\)71.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Noise level range of acoustic comfort zones. low pressure, the indoor temperature needed to be increased by 1-1.5 \({}^{\circ}\)C to obtain the same overall comfort evaluation as under standard atmospheric pressure. That is, a slightly warm environment could improve the POCV\({}_{\rm L}\) under low pressure. In Figure 11, with the noise level \(N=60\) dB, the changes in POCV\({}_{\rm L}\) per operative temperature unit change were different. The POCV\({}_{\rm L}\) change columns were connected in sequence, and the change trend followed a quadratic curve. The illuminance conditions corresponding to the curve positions from high to low were 550 lx, 250 lx, and 1000 lx. The closer the illuminance condition was to the luminous comfort zone, the greater the POCV\({}_{\rm L}\) change caused by the \(t_{\rm o}\) change. As shown in Figure 7, the maximum difference in POCV caused by a unit change in operative temperature was about 0.15 under standard atmospheric pressure [52]. The difference in POCV\({}_{\rm L}\) ranged from 0 to 0.3 under low pressure, representing a doubling of the variation. When the operative temperature decreased, the temperature difference for heat transfer increased, and the total heat loss from the human body increased [77]. Lower pressure also increases the body's heat loss. Therefore, low pressure had a greater influence at lower temperatures. From the above analysis, the influence of a unit change in operative temperature on POCV\({}_{\rm L}\) was non-uniform. When both the noise level and the illuminance were in the comfort zone, the operative temperature became the dominant factor affecting POCV\({}_{\rm L}\). However, as the other two parameters deviated from the comfort zone, the dominant role of the operative temperature was weakened. Changes in operative temperature more easily led to discomfort under low pressure. 2. Illuminance's influence on POCV\({}_{\rm L}\)  
Figure 11: The POCV\({}_{\rm L}\) difference changes with operative temperature (\(N=60\) dB). Figure 10: The changes in POCV\({}_{\rm L}\) with operative temperature (\(N=60\) dB). Figure 12 shows the POCV\({}_{\rm L}\) variation with illuminance. Taking \(\Delta E\) = 100 lx as the unit variable, it led to a non-uniform change in POCV\({}_{\rm L}\). When POCV\({}_{\rm L}\) was in the higher comfort zone of \(E\in\) [500 lx, 600 lx], the POCV\({}_{\rm L}\) change was gradual. As the illuminance either increased or decreased, the variation in POCV\({}_{\rm L}\) increased. In Figure 13, let \(t_{\rm o}\) = 22.4 \({}^{\circ}\)C. The 100 lx change is represented on the \(x\)-coordinate, while the \(\mid\Delta\)POCV\({}_{\rm L}\mid\) change is represented on the \(y\)-coordinate. The maximum difference in \(\mid\Delta\)POCV\({}_{\rm L}\mid\) increased to 0.6 under low pressure. Compared with the maximum value of \(\mid\Delta\)POCV\(\mid\) of 0.3 under standard atmospheric pressure [52], it nearly doubled. Connecting the differences in \(\mid\Delta\)POCV\({}_{\rm L}\mid\) in sequence, the curve followed a quadratic function. The curves from high to low corresponded to the noise levels of 60 dB, 70 dB, and 80 dB.