## 3 Results and Discussions
As sDA increased, UDI showed an increase tendency as well in the initial stage, but the reduction tendency of UDI became more and more significant with sDA attained a higher level. The reason is that sDA only has a minimum illumination limit of 300 lx. Indoor daylight illumination levels above 300 lx will be considered to meet the lighting requirements of the environment, and are used for sDA calculation. Except for a minimum illumination limit of 100 lx, UDI also adopts an upper illumination limit of 2000 lx. When daylight illumination level exceeds 2000 lx, UDI will take it as unwanted and may cause visual and thermal discomfort for the occupants. So, daylight illumination above 2000 lx is not taken into consideration in the UDI calculation. Judging the daylighting performance by just one indicator is not enough, so both of the sDA and UDI values need to be improved to achieve a better visual comfort environment. The correlation coefficient between EUI and BEC was 0.602, and the two objectives seemed to be positive correlated. However, EUI and BEC are supposed to have a negative correlation under normal circumstances. The reason is that most of the wall constructions of the non-dominated solutions adopted the expanded polystyrene board in the insulation layer as a result of optimization. This kind of insulation material is more cost-effective compared to other options, and a better thermal performance can be obtained at a relative low cost level. In addition, most of the non-dominated solutions adopted the double silver low-e coating glass window, which is relatively expensive. Therefore, when this type of window construction was used, the BEC could be higher as the window area was larger, and the increase of window area also caused the increase of EUI, so there was no contradiction between EUI and BEC in this case. The correlations between the other pairs of objectives were less significant. The relationship between EUI and UDI was nonlinear, the R value between the two objectives was -0.445, and from the scatter plot we can see that UDI increased at the initial stage but tended to decrease later with EUI increased, which suggest that the two objectives were contradictory when the EUI value was at a low level. The R value between sDA and BEC was 0.430, and from the scatter plot of the two objectives we can also observe a nonlinear relationship between them. As sDA increased, BEC didn't change much at first, but when sDA values reached a higher level, the growth of the BEC value accelerated, which suggests that sDA and BEC had a contradictory relationship in the range where sDA value was high. The correlation coefficient between UDI and BEC was lowest, with an R value of -0.354, from the scatter plot we can see that the non-dominated solutions were more densely distributed in the range where BEC was lower and UDI was higher, which demonstrates that the two objectives were not contradictory to each other. The comparison between the distribution range of the samples and that of the non-dominated solutions can be shown in Figure 14, the EUI values (unit: kWh/m\({}^{2}\)) of the samples were concentrated between 199.2 and 203.7, with a median of 201.6. The EUI values of the non-dominated solutions were centrally distributed between 196.6 and 203.3, with a median of 199.1. The sDA values (unit: %) of the samples were centrally distributed between 79.1 and 89.4, with a median of 84.1. The sDA values of the non-dominated solutions were centrally distributed between 82.2 and 95.1, with a median of 89.5. The UDI values (unit: %) of the samples were centrally distributed between 55.5 and 58.7, with a median of 57.1. The UDI values of the non-dominated solutions were centrally distributed between 56.6 and 60.9, with a median of 59.5. The BEC values (unit: %) of the samples were centrally distributed between 2.36\(\times\)10\({}^{6}\) and 2.90\(\times\)10\({}^{6}\), with a median of 2.66\(\times\)10\({}^{6}\).