MEAN WIND SPEED BELOW BUILDING HEIGHT IN RESIDENTIAL NEIGHBORHOODS WITH DIFFERENT TREE DENSITIES

There is little available know/edge of the absolute or relative effects of trees and buildings on wind at or befcm building height in residential neighborhoods. In this study, mean wind speed was measured at a height of 6.6 ft (2 m) In neighborhoods of single-family houses. BuIlding densities ranged between 6% and 12% of the land ares, and tree-cover densities were between 0 and 77%. Measurements were made wfth cup anemometers at points either V2 or 1 building height from 15 sample houses. An anemometer at 6.6 ft at a local airport provid­ ed the reference wind speed, Uoo Approach wind speeds toward houses in 8 neighborhood with no trees were reduced an average of 22% compared to Uo' In 8 neighborhood with similar building density and 77% tree density, reductions In approach wind by both trees and buildings averaged 65% In winter and 70% In sum­ mer. Empirical models were der;ved to predict the effect of trees on wind separately from the effect of buIldings. The models were based on tree and building geometry derived from' map measurements, aerial photos, and fisheye photos from wind-measuring points.