## 5 Results and Discussion  
Comparison of Ventilation Characteristics of Seven Window Types with Different Wind Directions under CV  
In CV, the window-opening angle was 30\({}^{\circ}\), and the window-opening area was equal. The simulated conditions of CV were divided according to the angle between the incoming wind direction and the plane of the window based on the 16-wind direction interval method, where 0\({}^{\circ}\) (360\({}^{\circ}\)) was condition 1, each increase of 22.5\({}^{\circ}\) was a condition, and 337.5\({}^{\circ}\) was condition 16. According to the left and right symmetry, the seven window types were divided into two types: symmetrical windows, namely THWI, THWO, BHWI, BHWO, and SW, and asymmetric windows, namely CWI and CWO. Figure 7 depicts the simulated wind pressure and discharge coefficients for different window types in different wind directions.  
As shown in Figure 7, the overall changing trend of the wind pressure coefficient of the symmetrical windows is similar. It is worth noting that on the windward side, the maximum value of the wind pressure coefficient does not appear at 0\({}^{\circ}\) (360\({}^{\circ}\)), but under the symmetrical condition of 22.5\({}^{\circ}\) (337.5\({}^{\circ}\)); there is a similar situation on the leeward side, where the minimum value of the coefficient appears in the symmetrical conditions of 157.5\({}^{\circ}\) (202.5\({}^{\circ}\)). For the asymmetrical window, the wind pressure coefficient is higher on one side for the left and right directions of the windward window, and the high and low directions of the CWI and CWO are opposite, and the trend is similar on the leeward side. The maximum and minimum values of the wind pressure coefficient still deviate from 0\({}^{\circ}\) (360\({}^{\circ}\)) and 180\({}^{\circ}\). The discharge coefficient of symmetrical windows fluctuates in a  
Figure 7: \(C_{p}\) and \(C_{d}\) of the (**a**) symmetrical window and (**b**) asymmetrical window.  
small range under different wind directions, and there is no obvious distinction between the windward and leeward sides. The discharge coefficient of the asymmetric window fluctuates considerably on the windward side and gently on the leeward side.  
Comparison of Ventilation Characteristics of Seven Window Types with Three Opening Angles under CV and SV  
In CV, the wind direction was fixed to the plane of the window. Three opening angles of each window type were simulated, in which the window opening state of the sliding window was set as one-third, two-thirds, and fully open, and the window-opening states of other window types were set as \(15^{\circ}\), \(30^{\circ}\), and \(45^{\circ}\), respectively. The three types of openings were defined as small, medium, and large openings, respectively.  
The discharge coefficients of the three opening angles for the seven window types under the two ventilation modes were simulated, as shown in Figure 8. The discharge coefficient for each window type under CV is generally larger than that under SV, and the difference in discharge coefficient of each window type of the three openings under SV is less obvious than that under CV, which is due to the different mechanisms of wind pressure ventilation and thermal pressure ventilation, resulting in different airflow characteristics at the openings. In addition, for CV and SV, the discharge coefficient increases with the increase in window opening, and the SW has the highest discharge coefficient under a large opening, which is 0.68, and 0.52, respectively. For medium and small openings, the discharge coefficient of BHWI is the highest under CV, and the discharge coefficient of THWI is the highest under SV.  
Figure 8: \(C_{d}^{\prime}\) of three openings for seven window types: (**a**) CV and (**b**) SV.