Paper 3
Strategies for Natural Ventilation
of Urban Office Buildings
Regan Potangaroa1 and Richard Aynsley2
1School of Architecture, UNITEC, Auckland,
New Zealand 2Big Ass Fans Australia Pty Ltd, Brisbane,
Australia
Abstract
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.
Key words: double façade buildings, high rise, natural
ventilation potential, wind tunnel measurements, air-well, wind catcher.
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