## 3 Results  
The tests were all done on fine days and the outdoor weather conditions were similar. Therefore, the indoor thermal environment parameters on 17 January were analyzed. The changes of indoor and outdoor temperatures of the residential building during the tests are shown in Figure 6.  
It can be concluded from Figure 6 that the outdoor temperature varied from \(-\)7.6 to 2.5 \({}^{\circ}\)C and the mean temperature was \(-\)2.7 \({}^{\circ}\)C. The indoor average temperature was 9.48 \({}^{\circ}\)C in the main function room, and the average temperature in the secondary function room was 4.02 \({}^{\circ}\)C. The average surface temperature of the west wall of the main bedroom was 9.45 \({}^{\circ}\)C. To conclude, in this region it is cold and the indoor temperature is low in winter. The changes of solar radiation intensity during the tests are as shown in Figure 7.  
Figure 5: (**a**) Fluid domain and (**b**) meshes around the building in the simulation. Figure 6: Indoor and outdoor temperatures of the residential building. Figure 7 shows that the local sunshine duration was about 11 h, the solar radiation intensity was 286 W/m\({}^{2}\) on average and came to the peak value of 544.8 W/m\({}^{2}\) at around 4:00 pm, the scattered radiation intensity was 124.9 W/m\({}^{2}\), and the direct solar radiation intensity accounted for about 80% of the total radiation intensity. In summary, the sunshine in this area lasts longer and the solar radiation intensity is higher. The solar radiation certainly needs to be considered and explored further in the building designs. Figure 8 shows that when the air temperature of the main bedroom was 9.48 \({}^{\circ}\)C, the surface temperatures of the west and east side walls of the main bedroom were about 7.23 \({}^{\circ}\)C and the inside surface temperature of the north wall was 4.87 \({}^{\circ}\)C, which is about half of the room temperature. It can be seen from Figure 9 that heat flux at the middle section of the partition wall between the main bedroom and the second room was 3.04 W/m\({}^{2}\). The relatively large heat flux occurred at the window corners at south and north walls of the main bedroom. From the simulation results, the flow rate from the main bedroom to the second bedroom through the partition wall was 55.3 W, and the heat flow through the north, south, and west side enclosures of the second bedroom was 260.5 W. The difference between the two heat flow rates is 205.2 W.  
The above heat flow rates were calculated based on the existing windows, which have a single layer of glass. If two layers of glass with a 12-mm air gap between them were installed, the heat flow  
Figure 8: Temperature distributions in the walls with natural convection on the surface. Figure 7: Solar radiation intensity outside the residential building. Figure 9: Heat flux through the walls under the free convection simulation. rate through the north, south, and west enclosures of the second bedroom would be reduced to 242.2 W, with a reduction of 18.2 W or about 7% of the current heat flow rate out of the second bedroom. North and west wind velocities around the buildings are shown in Figure 10a,b. Also, a sectional view of the velocity distribution in the north wind simulation is shown in Figure 10c. It can be seen from Figure 10 that the wind velocities around the building in the north wind is smaller than that in the west wind. Wind velocities on the top of the roof are much higher in the west wind than that in the north wind. The wind velocities at 0.5 m from the south and north wall surfaces are presented in Figure 11a,b in the north wind simulations, respectively. The velocities at 0.5 m from the south wall vary from 1.1 to 4.0 m/s. The velocities at 0.5 m from the north wall vary from 1.2 to 6 m/s. The wind velocities at 0.5 m from the south wall surface in the west wind are also shown in Figure 11c, which vary from 2.5 to 3.5 m/s. However, the wind velocities at 0.5 m from the north wall surface in the west wind, as shown in Figure 11d, vary from 2.2 to 5.8 m/s.