The Cooling Effects of Plant and Green Land
Date Issued
2010
Date
2010
Author(s)
Lin, Bau-Show
Abstract
Urbanization causes urban climate and worsens urban heat island effect. Since urban area is the main settlement for humans, this study airmed to explore the existence benefit of green land and plant. In the urban scale, this study investigated the influence of urban land use on urban temperature. In the urban outdoor space scale, cooling effect of urban trees was studied and factors influence cooling effects were investigated. In building scale, this study explored the cooling effect difference among platforms covered by different plants. In addition, the factors influences the cooling effect were studied.
In the work of effects of land uses on urban temperature, this study collected urban temperatures and land uses in 16 Taiwanese cities during 1999–2006. The results show that percentage of land use zone area related to city center temperature. City center temperature strongly and negatively correlated with percentage of nonurban developed areas and percentage of agricultural zone. This study proposed models for predicting urban temperature. Study results may provide insight into how urban land use planning can mitigate urban heat island effect.
In the work of cooling effect of urban trees, this study examined 10 species of trees and 2 species of bamboos. In the summer of 2007, this study measured leaf and canopy characteristics of each species. The microclimate conditions under the tree canopies and an un-shaded open space were measured repeatedly in mid-days without precipitation. In comparison to the nearby un-shaded open space, air temperatures under the canopies were 0.64 to 2.52 °C lower while the surface-soil temperatures 3.28 to 8.07°C lower. Leaf color lightness, leaf thickness, leaf texture, and foliage density of shaded trees determined their cooling power.
In the work of cooling effect of green roof, this study monitored the temperature variance of green roof and compared the cooling effect difference covered by 12 plant species. Further, the relationship between plant characteristics and cooling ability was investigated. The results show that green roof had cooling ability. Platforms covered by different plants reduced roof floor temperatures ranged 12.90 to 22. 20°C. There were significant cooling effect differences among the plants. Plant height, plant albedo, growth type, photosynthesis type, and leaf thickness of plants determined their cooling power.
Subjects
Urban land use
Non-built area
Agricultural land
Foliage density
Plant selection
Extensive roof
Landscape
Microclimate
Type
thesis
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