A modeling investigation of the impact of building openings and podium configurations on personal air pollutant exposure in isolated deep urban canyons

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A modeling investigation of the impact of building openings and podium configurations on personal air pollutant exposure in isolated deep urban canyons

 

Author: Zhang, Xiao
Title: A modeling investigation of the impact of building openings and podium configurations on personal air pollutant exposure in isolated deep urban canyons
Degree: M.Sc.
Year: 2014
Subject: Buildings -- Environmental engineering.
Air -- Pollution
Hong Kong Polytechnic University -- Dissertations
Department: Faculty of Construction and Environment
Pages: 46 leaves : color illustrations ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2760628
URI: http://theses.lib.polyu.edu.hk/handle/200/7650
Abstract: In this study, the effectiveness of different configurations for two building design elements, building openings and podium configuration, proposed for mitigating or diluting air pollution problems in isolated deep canyons were evaluated using an indirect exposure approach. The indirect approach predicted the exposures of an individual by multiplying the pollutant concentrations with the duration of exposure within a specific micro-environment. In this study, a computational fluid dynamics model was applied to simulate and predict the pollutant concentrations for different building configurations. Based on the Reynolds-Averaged Navier-Stokes (RANS) equations, the computational model was constructed with the standard κ-ε turbulence model. Eighty-four canyon configurations having different building opening areas and heights or podium configurations were examined for aspect ratios of 2, 3, and 4. The findings indicated that pedestrian personal exposures were extremely high if they stayed in a canyon without any building openings or podium when the prevailing wind was perpendicular to the street axis. Building openings were shown to be an effective means to improve in-canyon air circulation and dilute the air pollutant concentration to a reasonable value under perpendicular wind despite their effectiveness being varied with type of configurations i.e. the ratio of the opening area to the area of the wall. Increasing the permeability value through increasing the opening areas from 0 to 10% significantly lowered the mean and maximum personal exposures at pedestrian level. And the highest effectiveness was achieved when the height of the opening was 5m from the ground level. Likewise, the personal exposures could also be reduced by the introduction of building podium whose effectiveness was not influenced by canyon aspect ratios as strongly as other building configurations. These findings provide valuable insights for urban planners.

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