Abstract:
Natural ventilation creates
comfortable and healthy indoor environments
without consuming energy. However,
maintaining adequate natural ventilation is
arduous because several factors control its
performance, including ambient wind speed
and direction, opening configurations, and
nearby objects such as vegetation. Among them,
the effects of vegetation on natural ventilation
are least understood. This study investigated
how tree plantation location and crown shape
affect the cross-ventilation of a generic building
with two openings using Computational Fluid
Dynamics (CFD) simulation. The CFD
simulations are based on the Reynolds Averaged Navier-Stokes (RANS) equations and
use source terms for momentum, turbulent
kinetic energy, and turbulent kinetic energy
dissipation rate to model the effects of trees on
the wind field. The results show a 23%
reduction in ventilation rate for trees at a 2H
distance upstream of the building (H is the
building height) compared to the ventilation
rate of a building without trees in its
surrounding. Beyond this distance, the
ventilation rate deficiency steadily decreases
with tree plantation distance and has no
reduction for trees planted at 15H upstream of
the building. The cuboid-shaped crown causes
the highest ventilation rate reduction of 23%
compared to the V-shaped (18%), oval (16%),
and conical (10%) crowns. This study
recommends no trees with cuboidal crowns
planting between 1.5H to 2.5H distances
upstream of the building and maintaining
aerodynamic tree crowns to minimize the
adverse effects of trees on the natural
ventilation of buildings.
