## 4 Influence of Space-Arrangement and Exterior Wall Thermal Resistance on Indoor Air Temperature
### Influence of Exterior Wall Thermal Resistance on Indoor Air Temperature
The above results show that in the natural working state of multi-space passive solar buildings, there is a significant difference between the heat transfer loss and the passive heat collection in each room, due to the directional characteristics of solar radiation and the complicated heat transfer process between adjacent rooms. Influence of Wall Thermal Resistance on Indoor Air Temperature Defence between Main and Auxiliary Rooms  
During natural operation, the indoor air temperature of the main room in a passive solar building is mainly affected by two aspects: One is the net amount of solar radiant energy collected by the building; the other is the proportion of heat allocated between the main and auxiliary rooms. The previous analysis results show that even if the thermal resistance of different exterior walls changes by the same amount, the temperature difference between the main and auxiliary rooms is different. Therefore, it is necessary to analyze the change trend of the temperature difference between the main and auxiliary rooms under the thermal resistance increment of exterior walls in different orientations. Figure 13 illustrates the variation of indoor air temperature difference between main and auxiliary rooms with the thermal resistance increasing of the exterior wall in the indoor space-arrangement mode \(c\). To simplify the analysis, the indoor air temperature of the main room is defined as the average indoor air temperature of the bedroom 1, bedroom 2, and living room, and the indoor air temperature of the auxiliary room is defined as the average temperature of the storage room 5, storage room 6, and kitchen. Figure 14 presents the indoor air temperature differences between the main and auxiliary rooms when the thermal resistances of the exterior walls in different orientations are increased from 0.53 m\({}^{2}\cdot\)K/W to 1.86m\({}^{2}\cdot\)K/W. From Figure 13 it can found that increasing thermal resistance of the north wall decreases the temperature differences between the main and auxiliary rooms. When the thermal resistance of the north wall is increased from 0.53 m\({}^{2}\cdot\)K/W to 1.86 m\({}^{2}\cdot\)K/W, the indoor air temperature differences between the main and auxiliary rooms decline from 6.3 \({}^{\circ}\)C to 4.9 \({}^{\circ}\)C, and decreases by 22.2%. Due to the temperature increasing of the auxiliary room, the temperature difference between the main and auxiliary rooms decreases with the thermal resistance increasing of the north wall. Compared with the air temperature rise caused by increasing thermal resistance of the south wall and the east/west wall from 0.53 m\({}^{2}\cdot\)K/W to 1.86 m\({}^{2}\cdot\)K/W, the thermal resistance increasing of the north wall can increase the indoor air temperature of the auxiliary room by 36.7% and 21.8%. Meanwhile, the temperature values in Figure 14 indicate that the proportion of thermal energy distributed in the main room can be improved by increasing the thermal resistance of the south exterior wall, but the overall indoor thermal environment of the building does not improve significantly. It can be deduced that as the heat transfer loss of the building through the east/west wall decreases with the increase of thermal resistance, the indoor air temperature of the main room increases significantly, while the temperature of the auxiliary room increases slightly. It can be seen from Figure 14 that when the east/west wall adopts the maximum thermal resistance of 1.86m\({}^{2}\cdot\)K/W, the indoor air temperature of the main room is 12.4 \({}^{\circ}\)C, which is 8.8% and 6.9% higher than that of the same thermal resistance of the south wall and the north wall. The above result is attributed to the increase of the east/west wall thermal resistance increasing the net heat gain of the main room, thereby increasing the indoor air temperature of the main room.