Displacement ventilation (DV) has been found to be effective in cooling large indoor spaces, but its effectiveness in providing thermal comfort in tropical buildings requires more detailed analysis to be made. This study examines the thermal environment in a lecture hall cooled via DV using FloEFD, a computational fluid dynamics (CFD) software. A calibrated CFD simulation model was developed to replicate the actual atmospheric conditions of the DV-cooled lecture hall. Results indicate that some parts of the hall received more cooling and air movement than required which would result in local thermal discomfort, especially at the front seating areas. The CFD results were consistent with those of earlier studies which validated the simulation model. The findings can be used to determine the locations which are more prone to steep thermal gradients in addition to reducing thermal discomfort, which include suitable arrangements of occupants in the lecture hall when it is not fully occupied and resetting the diffusers’ supply air temperature.
Building overhang is an essential element in the construction of terrace
houses in Malaysia to protect occupants from the sunlight, car parking, and
social event purposes. However, there is still a lack of study investigating the
effect of overhang in a windy area of terrace houses despite its effect on the
flow modification around the building. Therefore, in this paper, a series of
computational fluid dynamics (CFD) simulations were performed using
Reynolds Average Navier Stokes(RANS) equations and renormalization
group (RNG) k – ε as the turbulence closure model. Simulations were
conducted on a unity aspect ratio of two-dimensional street canyon
representing the low-rise terrace house area in a flat roof shape and three
different overhang conditions. The protruding overhangs were significantly
modified the in-canyon flow structure as it limited the penetration of the
above flow into the canyon as compared to the without overhang case. In
addition, spatially-averaged ? of the turbulent kinetic energy depicted that
the value decreased within the canyon, demonstrating the independence of
the overhang location. It is recommended to perform a further study on the
ventilation performance of the street canyon through evaluation of
ventilation indices such as ventilation rate, air exchange rate (ACH), and
pollutant exchange rate (PCH).
Pedestrian level in the urban area is an important area where most of pedestrians’ activities occur at this
level. Therefore, the purpose of this study is to investigate effects of various building layouts on mean
wind speed ratio at the pedestrian level. The mean wind speed ratio at the pedestrian level was analysed
in order to determine whether the building layouts configured within this research are able to enhance
outdoor ventilation and ensure good pedestrian comfort level. The simulation model consists of two main
areas which are the upstream area and downstream area with a setback distance, d. The building layouts
at upstream area are arranged in staggered arrangements (ST) or square arrangements (SQ), while the
downstream areas are in a fixed staggered arrangement (ST). Packing density in both areas is 25% with
three setback distances which are 3H, 5H and 7H. Based on the results, the mean wind speed ratio at the
pedestrian level in a downstream area with longer setback distance will provide a higher mean speed ratio,
and the influence of upstream building arrangements on the mean wind speed ratio of the downstream
area decreases as the setback distance increases. Hence, the mean wind speed ratio of downstream area
depends on the setback distance between the upstream and downstream areas.