Experimental investigation of wind characteristics and wind energy potential over rooftops: Effects of building parameters

In this study, the wind flow characteristics and wind energy potential over the flat rooftops of tall buildings were investigated systematically via wind tunnel testing. The effects of building parameters such as the building height ratio (H-r = 3, 5, and 7) and the building width ratio (W-r = 1, 2, and 3) were examined. Due to symmetry, the experiments were conducted up to 90 degrees wind direction in a simulated boundary layer flow in increments of 22.5 degrees. For a given building, a 3 x 3 array of points was set on the roof plan and stretched vertically up to a height of z = 2H, H for building height. The vertical wind profiles over the rooftops showed similar patterns at various locations and wind directions. The maximum wind energy amplification factor Cw,max generally increased with Wr and Hr, but it was far more sensitive to W-r than to H-r. The C-w,(max) values ranged from 1.6 to 2.7, which suggests the great potential for a large wind energy yield over rooftops. However, hub heights from z/H = 1.02 to 1.19 demonstrated much lower values than those given in the literature. This study provides valuable experimental data for the guidance of roof-mounted wind turbines.