Effect of shading with trees to improve local temperature conditions
2019
Cao, V.D., Czech Univ. of Life Sciences, Prague (Czech Republic) | Kic, P., Czech Univ. of Life Sciences, Prague (Czech Republic)
Planting trees in living environments can mitigate outdoor thermal stress and reduce solar radiation to the surfaces of buildings as well. Modification of outside microclimates using certaintypes of tree cover can provide important benefits to the space around trees or walls of buildings. However, how beneficial is each type of trees, is not clear. The aim of this paper is to present the measured results of solar radiation, globe temperature, surface temperature, air temperature in the shade of typical trees cultivated in the living area inside cities. The measured results are compared with the same measurements of unshaded surfaces. Based on the obtained results, the cooling effect and the largest benefit of the tree canopy of several tree species can be evaluated. For this research five distinct areas shaded by individual grown trees or groups of trees (Paulownia tomentosa, Acer saccharinum, Picea pungens “Glanca”, Carpinus betulus, Tilia platyphyllos and Acer platanoides) were selected. The measurements were carried out during very hot summer days with average air temperatures from 35 to 40 ºC and solar radiation from 700 to 1,000 W•mE−2. The coverage of the canopy does not only benefit the space under the trees, but also influences the reduction in the air temperature as well as radiation of the texture of buildings close to the trees. Direct solar radiation under trees in the shaded areas was reduced from 79.4 to 94.4 % of unshaded conditions. Therefore, it contributes to reducing the air temperature inside the building in summer in sunlight. The reduction in the air temperature under different species of trees is not the same. For example, under the cluster Tilia platyphyllos and Acer platanoides, the reduction in the air temperature was 20.8 %, while under the tree Carpinus betulus, it was 13.7 %. This study clearly demonstrates the microclimate benefits of the air temperature reduction under the canopy of certain types of trees and provides guidance for residential planners in strategic tree planting.
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