4. Design Methods for Particular Overhang Types

This chapter deals with overhang studies that do not easily fit the previous two chapters due to their innovative approaches. The first two sections bring the methods motivated by Kaftan’s remark that one should not expect optimal overhang shape to be of simple geometry even for a rectangular window, as solar gains and daylight intensities vary with changing solar angles. Methods in the first section are based on the division of the underlying overhang support surface into a cell array which are then treated individually, while the second section discusses a method that divides the support surface into a one-dimensional array of strips attached to the wall, whose outer edges are modelled by a smooth, continuous NURBS line. The third section presents a method in which the shading design problem is reversed so that instead the window is trimmed to optimally suit a given rectangular overhang. The fourth section discusses the results of a few studies that recommend overhangs as suitable exterior shading devices for building retrofits due to their structural properties. The last section describes methods for constructing and optimising PV integrated overhangs, whose sunny side uses blocked direct solar radiation to generate electricity, and movable overhangs, whose position can be updated from season to season.