Home Engineering Sustainable High Rise Buildings in Urban Zones: Advantages, Challenges, and Global Case Studies
The existence of high-rise buildings will influence the microclimate of their neighbouring area. They act as obstacles to, and pathways for, the wind, allowing streets with taller buildings to capture more fresh air (Hang et al. 2012). At the same time, some air pollutants will be discharged into the atmospheric environment from high- rise buildings. They include lampblack from kitchens, exhaust gas from toilets, hot air from air condensing units, exhaust gases from underground garages and bad smells from refuse storage areas. The degree of air pollution usually intensifies in the morning and evening rush hours. It is difficult for air pollutants to dilute and diffuse in the area with a high density of buildings, especially for large-scale blocks of high-rise buildings.
Some tests have been conducted in Zhengzhou to explore the characteristics of the vertical distribution of particulate matter (Liu et al. 2009). As for TSP and PM10, the concentration declines with the elevation until the height reaches around 60 m, then the concentration increases with the elevation. As for PM2.5 and PM1, the concentration increases with the elevation. On lower stories, the concentration levels are mainly subject to gravity; however, on the higher stories, the concentration levels are mainly subject to atmospheric turbulence (see Fig. 4.3).
B. Li and R. Yao
Fig. 4.3 Vertical distribution of particle pollution in the atmosphere (Liu et al. 2009)
Table 4.1 Thermal comfort criteria for offices
Natural ventilation is widely promoted in high-rise buildings for its energysaving potential with its effect being mainly influenced by wind speed, direction and architectural composition (Cui et al. 2012). As shown in Fig. 4.4, during the natural ventilation process, the exhaust air of one flat may become the intake of the adjacent upper flat, and vertical upward transport of contaminants between flats in high-rise residential buildings with natural ventilation will cause problems for the airborne transmission of infection (Gao et al. 2008a). According to tests and simulation work carried out in Hong Kong, in a high-rise building, normally 5 % of the exhaust air will enter the room upstairs due to buoyancy lift (Gao et al. 2008b). Studies have proved that the stack effect plays a very important role in indoor airborne virus transmission from lower floors to higher floors in high-rise hospital buildings (Lim et al. 2011). While wind tunnel tests on a 1:30 scale model of a 10-story residential building illustrated that pollutants can not only spread both upward and downward in the vertical direction, but also in horizontal directions (Liu et al. 2010).
In the buildings with an atrium, the concentration of pollutants in the atrium is higher than that in the surrounding areas with more contaminants being found on higher floors than on lower floors. The same tendency appears in the buildings with long corridors (Zhou 2006).
Mobile-source-related pollutants CO and PM10, as well as volatile organic compounds (VOCs), have been studied in high-rise apartment buildings. The outdoor air concentrations of CO and PM10 are much lower in higher-floor apartments compared to those on lower floors. Also, their concentrations were significantly higher in the winter and summer. But the difference of indoor CO and PM10 concentrations between the lower-floor and higher-floor apartments varies with season. Closing a major roadway will lead to a significantly higher PM10 concentration both indoors and outdoors. While CO indoor and outdoor concentrations did not
Fig. 4.4 An illustration of air pollutant cascade transfer under natural ventilation (Gao et al. 2008a, b) vary much according to the distances from major roadways (Jo and Lee 2006). When considering VOCs, their ambient concentrations are much higher in summer for both low and high floors (Jo and Kim 2002).
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