Role of Landscape Elements in Ameliorating Adverse Pedestrian Level Winds in the Vicinity of Tall Buildings

Tall buildings cater to the need for increased workspace with a reduced footprint, enhance the skyline, and image and increase the prestige of a city. Tall buildings also tend to intercept upper level high velocity winds and deflect them down to ground level, giving rise to conditions that could be unpleasant or even dangerous to pedestrians. Such accelerated winds also reduce the appeal of plazas, outdoor cafes, parks and pedestrian access-ways. Vertically accelerated downward wind flows can be mitigated with the help of architectural elements like podia or, canopies. Horizontally accelerated flows are best ameliorated with soft and hard landscape elements such as trees, shrubs and porous fences. This paper reports results of wind tunnel investigations that have been carried with the objective of assessing the role of landscape elements in moderating the pedestrian level wind environment in the vicinity of tall buildings. The tests have been carried out in the de Bray boundary layer wind tunnel at the University of Auckland on a representative model of a tall building suburb in New Delhi using the erosion technique enhanced with an image processing system. The results of the tests have brought out the effectiveness of landscape elements such as trees and porous fences in mitigating adverse horizontal winds in the vicinity of tall buildings.