# A Parametric Study of Wind Pressure Distribution on Facades Using Computational Fluid Dynamics
## 5 Discussion and Interpretation
### Sheltered Case
However, it is advised to use brackets for fin lengths of greater size, as peak pressures result in high forces acting on the fin. There is also a greater increase in force, with length, than when higher levels of circulation around the fins occur. The optimal arrangement in terms of force is to have a bracket length of 400 mm with a fin length of 560 mm. The second measure of facade performance is where the most efficient designs tend to minimize bending moments that act on the connection of the fin to the bracket, or the building. If stresses caused by moments can be minimized, connection details can be simplified, with economic savings from reducing the number of high-grade components involved in the transfer of bringing loads to the ground. Figure 17 is a contour plot of the peak moments based on the sample of 13 facade arrangements (using the same interpolation approach from Figure 16). Figure 16: Contour plot of peak net force in terms of normalized fin length, for a given facade element. From this contour plot, several trends are apparent. For increases in fin length, moments tend to increase, for a given spacing from the building. The exception to this exists for fins with brackets that are 480 mm long, which have improved efficiency compared to the fins of 400 mm length. Increasing the bracket length has the effect of increasing overturning moments at the connection with the top of the fin. Relative efficiency for longer fin lengths between 640 mm and 800 mm are found from having the second smallest bracket size of 160 mm, rather than the 80 mm length that is most efficient when used elsewhere. When no bracket is used, the arrangement tends to outperform comparable fin lengths in the 320 mm and 400 mm bracket length cases. There also appears to be reduced moments for some fin lengths at 400 mm that are more efficient for gaps equal to 160 mm and 240 mm, and with fin lengths equal to 480 mm, 560 mm and 640 mm, there is an improvement over the use of a 240 mm bracket length. The optimal facade arrangement for moments is where the bracket length equals 80 mm and fin length is 480 mm, and is derived from interpolation. The results of Figures 16 and 17 are normalized by relative scores of '1' for the most efficient facade geometry up to '36' for the least efficient type, to produce the plots in Figure 18. For each of these facade arrangements, the two scores were summed and a new range of values between '2' and '72' were produced. Based on the renormalization of these scores to values from '1' to '36', the contour plot to evaluate overall efficiency is plotted in Figure 19.  
The optimal facade design, where moments and loading of the fin element have equal importance for defining efficiency, has a fin length of 560 mm and a bracket length equal to 80 mm. In the context of the other facade geometries, it performs 5 th overall for loading and 7 th for moments that acts on the bracket connection. The top five most efficient designs were established as each having fin lengths of 560 mm, with sequential improvement with decreasing bracket length from 400 mm to 80 mm. The least efficient facade was model number '11', which was attached to the building directly and has the longest fin dimension at 800 mm. It performs worst of all for minimizing its load distribution, while also ranking 34 th for peak moment efficiency. Figure 17: Contour plot of peak moment for a given fin element.