# Wind Pressure Coefficient on a Multi-Storey Building with External Shading Louvers
## 4 Results and Discussion
### Features of Local Wind Pressure Coefficient along Measurement Lines
#### 4.2.1 Local Wind Pressure Coefficient on W-R-L Lines  
Figure 12a,b present the local range \(R\), local and average value of wind pressure coefficient \(C_{\rm p}\) on the central lines of R1 and R7 along the windward, roof and leeward surfaces under different shaded conditions. Generally speaking, the roof suffers the largest fluctuation of \(C_{\rm p}\), while the leeward surface has the smallest difference of the local \(C_{\rm p}\) and \(R\) along the lines. The maximum and minimum value of \(C_{\rm p}\) are 0.86 and \(-\)1.08, respectively. The \(C_{\rm p-max}\) line and \(C_{\rm p-min}\) line have the similar shape and tendency except near the edge of the roof for around 1-1.4\(H_{0}\) where has a flow separation. On the line of the windward facade, the maximum \(R\) is at about 0.8-0.9\(H_{0}\) on the stagnation zone and the minimum \(R\) is near the edge between the windward and the roof surfaces. The \(R\) along these lines increases along 0-0.1\(h_{0}\), but the local \(C_{\rm p}\) decreases. From 0.1\(h_{0}\) to 0.7\(h_{0}\), the local \(C_{\rm p}\) and the \(R\) both increase. After 0.7\(h_{0}\), the local \(C_{\rm p}\) in some cases begins to decrease but the \(R\) still grows up until around 0.9\(h_{0}\). These results indicate that near the maximum positive \(C_{\rm p}\) on the stagnation zone, the \(C_{\rm p}\) is strongly sensitive to the rotation angle \(\theta\) of shading louvers. For the area near the vortex at the corner of the windward facade and the ground, the \(C_{\rm p}\) is not sensitive to different shaded conditions. On the lines of the roof, the \(C_{\rm p}\) suffers a sharp decrease near the edge, which is the continuation of the windward surface. Then the \(R\) increases to the widest at 1.05\(h_{0}\). In this area, the blocking effect of shading louvers makes the \(C_{\rm p}\) tendency smoother along the roof line. On the leeward line, the local \(C_{\rm p}\) just changes slightly at different points due to the leeward recirculation. Figure 11: Arrangement of rooms and measurement lines. (**a**) Locations of seven rows and five floors, (**b**) W-R-L lines along windward, roof and leeward surfaces; (**c**) W-S-L lines along windward, lateral and leeward surfaces; and (**d**) R-S lines along roof and lateral surfaces. Figure 12c,d present the local range \(R\), local and average value of wind pressure coefficient \(C_{\rm p}\) on the central lines of R2 and R6 along the windward, roof and leeward surfaces. Generally speaking, the tendencies of the \(C_{\rm p-max}\) line and the \(C_{\rm p-min}\) line along the lines in Figure 12d are similar to those in Figure 12b. The \(R\) along the central lines of R2 and R6 is smaller than that along the central lines of R1 and R7. However, there are also some significant differences between the two locations. On the windward surface, the \(R\) along the central lines of R2 is always larger. Even if the maximum \(C_{\rm p}\) on two locations are almost the same, the local \(C_{\rm p-min}\) near the ground is obviously different between two locations. the \(C_{\rm p-max}\) along the central lines of R1 is over 0.5 within 0-0.9\(h_{0}\), but the \(C_{\rm p-max}\) along the central lines of R2 is below 0.5 within 0-0.3\(h_{0}\). The shape difference on the \(C_{\rm p-min}\) line is not as obvious as that on the \(C_{\rm p-max}\) line. The \(C_{\rm p-min}\) along the central lines of R2 is about 0.2 smaller. These differences mean that on the lines of R2, the windward surface tends to suffer a larger fluctuation of positive wind pressure. On the roof, the shape and tendency of the \(C_{\rm p-max}\) and \(C_{\rm p-min}\) on the central lines of R2 and R6 are almost the same as those on the central lines of R1 and R7, and only the \(R\) is a little smaller for most locations than the central line. On the leeward, the gradient and the maximum value of \(C_{\rm p}\) along the central lines of R6 are slightly lower than those along the central lines of R7.