Lowering the outdoor temperature in high-rise high-density residential developments of coastal Hong Kong: The vegetation influence

Giridharan, Renganathan; Lau, Ssy; Ganesan, S.; Givoni, Baruch

doi:10.1016/j.buildenv.2007.10.003

Cited by 134 publications

(68 citation statements)

References 9 publications

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“…However, in Hong Kong, the air temperature of the city center was lower than that of the sub-center due to the ventilation effect and the smaller amount of solar radiation [6,7]. This result indicates that increasing the building density does not necessarily increase the air temperature in urban areas.…”

Section: Introductionmentioning

confidence: 61%

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Association between Three-Dimensional Built Environment and Urban Air Temperature: Seasonal and Temporal Differences

Park

Lee

2017

Sustainability

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Climate change and the urban heat island phenomenon are increasingly important issues in urban thermal environments. However, there is a lack of research on the relationship between three-dimensional built environments and air temperature. Therefore, the purpose of this study is to provide policy suggestions that could be used to improve urban thermal environments by analyzing the effect of the three-dimensional built environment of an urban space on the urban air temperature according to changes in time (i.e., season, time of day). Using data from 236 automatic weather stations (AWSs) in Seoul, Korea, this study focused on three-dimensional built environmental variables and land use variables that affect air temperature in terms of season and time. The analysis results indicate that the sky view factor and porosity were lower in urban areas, with higher sky view factor and porosity values associated with lower air temperature. This study also indicates that surface roughness is higher in urban areas, with higher surface roughness associated with higher air temperature. These results suggest that urban design practices should consider the three-dimensional built environment when planning urban development and urban regeneration projects in order to improve the urban thermal environment.

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Section: Introductionmentioning

confidence: 61%

“…These differences are attributed to the different number of samples, study area, and other weather factors such as wind and humidity. In addition, few studies have analyzed how buildings, roads, and open spaces interact with solar radiation and wind [6,7,36].…”

Section: Introductionmentioning

confidence: 99%

Association between Three-Dimensional Built Environment and Urban Air Temperature: Seasonal and Temporal Differences

Park

Lee

2017

Sustainability

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“…Therefore, green cover ratio, tree cover ratio, and lawn cover ratio are usually adopted to quantify the vegetation in urban climate research, which are normally found to be negatively related with air temperature [39,92,93]. Among all vegetation types, trees are considered more influential on air temperature reduction than grass, since tree canopy can provide shading in addition to the evapotranspiration effect [6,36,94,95]. The cooling effect of trees depends on the species and canopy size.…”

Section: Urban Vegetation Descriptorsmentioning

confidence: 99%

The Impact of Urban Design Descriptors on Outdoor Thermal Environment: A Literature Review

et al. 2017

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This paper presents a literature review on urban design indicators addressing the impact of urban geometry and vegetation on the outdoor thermal environment at the pedestrian level, as urban geometry and vegetation have been regarded as the most influential urban design factors that affect outdoor microclimate. The thermal balance concept is first introduced to elaborate how each component of energy fluxes is affected by the urban built environment, which helps to explore the underlying thermophysical mechanisms of how urban design modifies the outdoor thermal environment. The literature on numerous urban design descriptors addressing urban geometric characteristics is categorized into five groups in this paper according to the design features that the parameters entail, including land use intensity, building form, canyon geometry, space enclosure and descriptive characteristics. The literature on urban vegetation descriptors is reviewed together, followed by the combined effect of urban geometry and vegetation. This paper identifies a series of important urban design parameters and shows that the impact of design parameters on thermal environment varies with time, season, local climate and urban contexts. Contradictory impacts often occur between daytime and nighttime, or different seasons, which requests trade-offs to be achieved when proposing design strategies.

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“…The results demonstrated that temperatures were reduced and humidities were elevated under the canopies of all the trees; however, the difference between species was insignificant, and the clumps had no greater effect than the individual tree. In another project, Giridharan et al [17] noted that, in high-rise high density urban environments, the influence of vegetation in lowering outdoor temperature was affected by the on-site variables such as sky view factor and altitude. Chow et al [18] examined the horizontal and vertical nocturnal cooling influence of a small park with an irrigated lawn and xeric surfaces in a hot-arid city.…”

Section: Introductionmentioning

confidence: 99%

Diurnal Thermal Behavior of Pavements, Vegetation, and Water Pond in a Hot-Humid City

Yang

Zhao

2015

Buildings

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This study investigated the diurnal thermal behavior of several urban surfaces and landscape components, including pavements, vegetation, and a water pond. The field experiment was conducted in a university campus of Guangzhou, South China, which is characterized by a hot and humid summer. The temperature of ground surface and grass leaves and the air temperature and humidity from 0.1 to 1.5 m heights were measured for a period of 24 h under hot summer conditions. The results showed that the concrete and granite slab pavements elevated the temperature of the air above them throughout the day. In contrast, the trees and the pond lowered the air temperature near ground during the daytime but produced a slight warming effect during the nighttime. The influence of vegetation on air temperature and humidity is affected by the configurations of greenery. Compared to the open lawn, the grass shaded by trees was more effective in cooling and the mixture of shrub and grass created a stronger cooling effect during the nighttime. The knowledge of thermal behavior of various urban surfaces and landscape components is an important tool for planners and designers. If utilized properly, it can lead to climatic rehabilitation in urban areas and an improvement of the outdoor thermal environment.

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Lowering the outdoor temperature in high-rise high-density residential developments of coastal Hong Kong: The vegetation influence

Cited by 134 publications

References 9 publications

Association between Three-Dimensional Built Environment and Urban Air Temperature: Seasonal and Temporal Differences

Association between Three-Dimensional Built Environment and Urban Air Temperature: Seasonal and Temporal Differences

The Impact of Urban Design Descriptors on Outdoor Thermal Environment: A Literature Review

Diurnal Thermal Behavior of Pavements, Vegetation, and Water Pond in a Hot-Humid City

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