## 4 Influence of Space-Arrangement and Exterior Wall Thermal Resistance on Indoor Air Temperature
### Influence of Exterior Wall Thermal Resistance on Indoor Air Temperature  
Due to the temperature difference between adjacent rooms in a multi-space passive solar building, there is not only heat transfer between indoor and outdoor, but also heat transfer between adjacent rooms. Therefore, the change of the thermal resistance of the exterior wall in different orientations has different effects on the indoor air temperature of each room. It is investigated that, in the space-arrangement mode \(c\), the indoor air temperatures of the main rooms varied with the increasing thermal resistance of the exterior walls, and the result is shown in Figure 11.  
It can be seen from Figure 11 that increasing the same amount of the thermal resistance of different exterior walls has different effects on the indoor air temperature of the main room. The indoor air temperatures of the mode \(c\) were analyzed under the condition of thermal resistance change of different exterior walls. It is deduced that the indoor air temperature of the mode \(c\) varies with the thermal resistances of diverse orientation walls. Figure 12 shows the increment of indoor air temperatures of all rooms caused by increasing thermal resistance of exterior walls in different directions. From Figure 12, it can be seen that the effect of the wall thermal resistance on the indoor air temperature is different even if the thermal resistance of walls in different orientations is equally increased. Through the comparative analysis of Figure 12a-c, it can be found that increasing the thermal resistance of east/west walls can significantly increase the indoor air temperature of the main rooms (living room and bedrooms). However, increasing the thermal resistance of the north wall can increase the indoor air temperature of the auxiliary room more obviously. Figure 11: Indoor air temperatures of the main rooms change with the thermal resistance of the exterior walls in mode \(c\). Figure 12a presents that as the thermal resistance of the south wall increases, the indoor air temperature in each room rises slightly, and the temperature rise in the main room is slightly higher than that in the auxiliary room. When the thermal resistance of the south wall increases from 0.53 m\({}^{2}\).K/W to 1.86 m\({}^{2}\).K/W, the indoor air temperature of the living room and bedroom (the average value of indoor air temperature in bedroom 1 and bedroom 2) increases by 0.29 \({}^{\circ}\)C and 0.22 \({}^{\circ}\)C, and the temperature increment of auxiliary rooms is less than 0.11 \({}^{\circ}\)C. However, under the condition of the same increment of the north wall thermal resistance, the air temperature of the auxiliary rooms increases significantly, while the indoor air temperature of the living room and bedroom only slightly increase by 0.55 \({}^{\circ}\)C and 0.46 \({}^{\circ}\)C, respectively (Figure 12b). Figure 12c indicates that the same increment of the east/west wall thermal resistance has a greater impact on the indoor air temperature of the main rooms (bedrooms and living room) than those of the south and north walls. When the thermal resistance of the east/west walls is increased from 0.53 m\({}^{2}\).K/W to 1.86 m\({}^{2}\).K/W, the indoor air temperature of the living room and the bedroom increases by 0.73 \({}^{\circ}\)C and 1.56 \({}^{\circ}\)C, respectively. Comparing with the temperature rise in the living room and bedroom caused by the thermal resistance increasing of the south wall and north  
Figure 12: Indoor air temperature increases with the increase of exterior walls thermal resistance. (a) South wall; (b) north wall; (c) east/west wall. wall, that of the living room caused by the thermal resistance increasing of the east/west wall increases by 151.7% and 32.7%, and that of the bedroom increases by 609.1% and 239.1%, respectively.