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The world urban population is expanding, resulting in taller buildings and increased building density. This paper describes a design approach for the natural ventilation of high-rise buildings based on a double façade structure in which an external cladding is used in conjunction with a central air-well with wind catcher ("hood").
Boundary layer wind tunnel testing was used to determine wind pressure distributions for different wind directions on model buildings with different width to depth aspect ratios. Pressure coefficients, determined for the surface of the building behind the cladding, showed that negative (suction) pressures were developed. These negative pressures, in conjunction with the positive pressures produced by the air-well with a wind catcher (pointing into the wind) provide natural ventilation potential. The external cladding/hooded air-well building was compared with a conventional cross ventilated building in terms of thermal comfort for a range of climate conditions. The results indicated that the ventilation potential of the conventional building was dependent on the building orientation with respect to the prevailing wind, but the external cladding/hooded air-well system was found to be independent of wind direction.