Impact of tree locations and arrangements on outdoor microclimates and human thermal comfort in an urban residential environment

Zhao, Qunshan; Sailor, David J.; Wentz, Elizabeth A.

doi:10.1016/j.ufug.2018.03.022

Cited by 235 publications

(100 citation statements)

References 37 publications

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“…Zhang [28] stated that the impact of vegetation on both the heat environment and ventilation in hot and cold seasons depends on the tree arrangement, LAI, crown width and tree height. Zhao et al [42] found that two trees planted without canopy overlap provided the best microclimate and human thermal comfort benefits in the neighborhood due to the importance of shading in a hot, arid desert environment. In this study, we came to the same conclusion: that the arrangement of trees affects the microclimate on hot summer days.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Tree-Planting Patterns on the Microclimate within a Courtyard

Liu

Srebric

et al. 2019

Sustainability

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Current landscape design within a courtyard usually does not take into account the influence of the tree-planting pattern, which has an important influence on the outdoor microclimate and occupants’ thermal comfort. At present, the extent of the influence on the microclimate has not yet been made clear. Computational Fluid Dynamics (CFD) was employed to run this model under hot summer weather conditions. Field measurements validated the performance of the CFD model. This study conducted numerical simulations for five different tree-planting patterns, including (i) focused tree-planting (F), (ii) cornered tree-planting (C), (iii) multi-row tree-planting (R), (iv) surround tree-planting (S) and (v) no tree-planting (N). Our study found that the tree-planting pattern affects both the distribution of air temperature and the degree of local heat transfer. Specifically, the C, S and N patterns allow for higher ventilation in the studied courtyard, while the F and R patterns cause lower wind velocities and associated courtyard ventilation. The average air temperature for the C pattern is lower during summer afternoons than the other patterns. The wind flow pattern in the studied courtyard does not vary significantly with different tree-planting patterns. Nevertheless, the general relative humidity in the courtyard does not vary significantly with different tree-planting patterns, except for the N pattern. A future analysis is needed to investigate the mechanisms of the phenomenon.

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Section: Discussionmentioning

confidence: 99%

The Effect of Tree-Planting Patterns on the Microclimate within a Courtyard

Liu

Srebric

et al. 2019

Sustainability

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“…Similar conclusions were also reached in some of the previous studies. For example, tree canopy coverage is negatively associated with air temperature in Phoenix and Changchun [17,80]; however, the cooling capacity of the same number of trees is quite different, due to the distinct arrangement [17,70], location [81], tree species [28,32], and climate background [17]. On the contrary, the study in Prague and Brno suggests that adding trees (a 30% increase) in the compact midrise development might even increase air temperature [82].…”

Section: Discussionmentioning

confidence: 99%

Numerical Simulation of Local Climate Zone Cooling Achieved through Modification of Trees, Albedo and Green Roofs—A Case Study of Changsha, China

Chen

Zheng

2020

Sustainability

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By exploring the cooling potential of tree quantity, ground albedo, green roofs and their combinations in local climate zone (LCZ)-4, LCZ-5, and LCZ-6, this study focuses on the optimum cooling level that can be achieved in open residential regions in Changsha. It designs and models 39 scenarios by integrating in situ measurement and ENVI-met numerical simulation and further compares cooling effects of various combinations of the cooling factors. The results show that (1) an increased number of trees and higher albedo are more effective compared to green roofs in reducing summer potential temperatures at street level (2 m high) in three LCZs. Negative correlations are observed in the pedestrian air temperature with trees and ground albedo; (2) the effects of cooling factors vary among different LCZ classes, with the increased 60% more trees leading to lower outdoor temperatures for LCZ-4 (0.28 °C), LCZ-5 (0.39 °C), and LCZ-6 (0.54 °C), while higher albedo of asphalt surface (increased by 0.4) is more effective in LCZ-4 (reaches to 0.68 °C) 14:00, compare to LCZ-5 (0.49 °C) and LCZ-6 (0.38 °C); (3) applying combined cooling methods can provoke air temperature reduction (up to 0.96 °C), especially when higher levels of tree quantities (increased by 60%) are coupled with cool ground materials (albedo increased by 0.4). The results can contribute useful information for improving thermal environment in existing residential regions and future residential planning.

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“…Rather than analyzing thermal effects of urban greening on the urban microclimate [70] or the impact of anthropogenic emissions on urban air quality individually [71], this study presents a combined investigation of both aspects together. Differing from previous mesoscale [25] and idealized modeling studies [44], as well as stand-alone box models [51], we undertake a combined analysis of different approaches.…”

Section: Discussionmentioning

confidence: 99%

Urban Trees and Their Impact on Local Ozone Concentration—A Microclimate Modeling Study

et al. 2019

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Climate sensitive urban planning involves the implementation of green infrastructure as one measure to mitigate excessive heat in urban areas. Depending on thermal conditions, certain trees tend to emit more biogenic volatile organic compounds, which act as precursors for ozone formation, thus hampering air quality. Combining a theoretical approach from a box model analysis and microscale modeling from the microclimate model ENVI-met, we analyze this relationship for a selected region in Germany and provide the link to air quality prediction and climate sensitive urban planning. A box model study was conducted, indicating higher ozone levels with higher isoprene concentration, especially in NO-saturated atmospheres. ENVI-met sensitivity studies showed that different urban layouts strongly determine local isoprene emissions of vegetation, with leaf temperature, rather than photosynthetic active radiation, being the dominant factor. The impact of isoprene emission on the ozone in complex urban environments was simulated for an urban area for a hot summer day with and without isoprene. A large isoprene-induced relative ozone increase was found over the whole model area. On selected hot spots we find a clear relationship between urban layout, proximity to NOx emitters, tree-species-dependent isoprene emission capacity, and increases in ozone concentration, rising up to 500% locally.

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Impact of tree locations and arrangements on outdoor microclimates and human thermal comfort in an urban residential environment

Cited by 235 publications

References 37 publications

The Effect of Tree-Planting Patterns on the Microclimate within a Courtyard

The Effect of Tree-Planting Patterns on the Microclimate within a Courtyard

Numerical Simulation of Local Climate Zone Cooling Achieved through Modification of Trees, Albedo and Green Roofs—A Case Study of Changsha, China

Urban Trees and Their Impact on Local Ozone Concentration—A Microclimate Modeling Study

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