## 3 Results and Discussions
### Analysis of the Optimal Combination of Room Parameters  
According to the results of the range analysis of indoor air temperature and room energy consumption in the above Sections 3.1.2 and 3.2.2, the relationship curve (effect curve) between the four influencing factors and the analysis indicators is shown in Figure 7. The abscissa in the figure is the different levels of each factor, and the ordinate is the average indoor air temperature and the energy consumption per square meter of the room. In this study, when the average indoor air temperature is the highest and the energy consumption per square meter of the room is the lowest, the level corresponding to each factor is the optimal level of the factor. As shown in Figure 7a, factor A is at the same level, which is the 5 th level, simultaneously meeting the highest average temperature of the room and the lowest energy consumption per square meter of the room. From Figure 7c,d it can be seen that factors C and D are in the same situation as factor A. However, as the width of the \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Item** & **Level** & **Factor A** & **Factor B** & **Factor C** & **Factor D** \\ \hline \(R\)-value & 1.65 & 2.43 & 0.62 & 0.49 \\ Rank & & & A \textgreater{} B \textgreater{} C \textgreater{} D & \\ Optimal Level & 5 & 5 & 1 & 1 \\ Optimal combination & & & A\textgreater{} B\textgreater{} C\textgreater{} D\textgreater{} & \\ \hline \hline \end{tabular}
\end{table} 
Table 8: _Cont._  
Figure 7: The effect curve of each test factor and the average indoor air temperature/room energy consumption per square meter. (**a**) The length of the room; (**b**) The width of the room; (**c**) The width of the opening on the north wall of the room; (**d**) The distance from the lower edge of the opening to the floor. room increases in Figure 7b, both analysis indicators decrease. The decrease in the average indoor air temperature is greater than the decrease in the room's energy consumption per square meter. The level at which factor B satisfies the highest indoor air temperature is not the same as that at which it satisfies the lowest room energy consumption. Therefore, according to the analysis in Sections 3.1 and 3.2, two new combinations of the two indicators are obtained when they are, respectively, optimal. The optimal combination of indoor air temperature is A\({}_{5}\)B\({}_{1}\)C\({}_{1}\)D\({}_{1}\) (S26), and the optimal combination of room energy consumption is A\({}_{5}\)B\({}_{5}\)C\({}_{1}\)D\({}_{1}\) (S27). Next, the two new combinations are modeled and simulated to analyze further the optimal combination of the room and opening parameters. The boxplot of indoor air temperature in January of 27 schemes is shown in Figure 8. It can be seen from the figure that, of the Tibetan residential rooms with T-walls installed, the indoor air temperature in January ranges from 2.2 \({}^{\circ}\)C to 24.5 \({}^{\circ}\)C, and the average temperature is between 9.1 \({}^{\circ}\)C and 12.2 \({}^{\circ}\)C. No matter which scheme, the average indoor temperature is much higher than the average indoor temperature of the existing Tibetan dwelling test room (\(-\)0.94 \({}^{\circ}\)C) [21]. It can also be seen from the boxplot that the minimum, average, and maximum values of scheme S26, which is the optimal combination of indoor air temperature analyzed in Section 3.1, are higher than those of the other 26 schemes. This also verifies the conclusion obtained by ANOVA and range analysis, which is that the optimal scheme for indoor air temperature is scheme S26. The histogram of room energy consumption per square meter in January of the 27 schemes is shown in Figure 9. In January, the rooms' energy consumption per square meter ranged from 4.8 to 8.0 kW-h/m\({}^{2}\), and scheme S2 has the highest energy consumption per square meter, which is 8.0 kW-h/m\({}^{2}\). Scheme S27, which is the optimal combination of room energy consumption analyzed in Section 3.2, has the lowest energy consumption, at 4.8 kW-h/m\({}^{2}\).