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作者

来源

URBAN FORESTRY & URBAN GREENING,Vol.37,P.42-55

语言

英文

关键字

ENVI-met; High-density; Thermal comfort; Temperature reduction; Vertical greening; MEAN RADIANT TEMPERATURE; CLIMATE; WALLS; MICROCLIMATE; SIMULATION; MITIGATION; COMFORT; FACADES; IMPACT; ROOFS

作者单位

[Morakinyo, Tobi Eniolu; Lau, Kevin Ka-Lun; Ng, Edward] Chinese Univ Hong Kong, Inst Future Cities, Hong Kong, Peoples R China. [Lai, Alan; Ng, Edward] Chinese Univ Hong Kong, Sch Architecture, Hong Kong, Peoples R China. Morakinyo, TE (reprint author), Chinese Univ Hong Kong, Inst Future Cities, Hong Kong, Peoples R China. E-Mail: tobimorak@cuhk.edu.hk

标签

城市环境,城市景观 | 其他

摘要

To improve outdoor thermal environment and reduce indoor energy use, passive techniques including facade greenery have been suggested. In high-density cities like Hong Kong, buildings' surface area is much greater than the roof and ground surface areas combined, offering a huge vertical surface platform for greening. However, scientific evidence to assert the thermal benefit from this greening option especially at neighborhood scale is still very few. Therefore, this study was designed to provide such evidence using results from validated ENVI-met model simulation. Thereafter, parametric study was conducted to investigate the quantity and location of facade greening required for potential air cooling and thermal comfort improvement of a neighborhood of varying densities. Model validation results revealed an acceptable modelling of facade surface temperature, air temperature, relative humidity and wall-emitted long-wave fluxes. From the parametric study, we found that 30-50% of facades in the high-density urban setting of Hong Kong must be greened to potentially cause -1 degrees C reduction in both daytime and nighttime air temperature while the same could help improve daytime pedestrian thermal comfort by at least one thermal class. We also established that higher greened facade ratio will be required to obtain similar thermal benefits in low and medium density urban settings. Also, realized benefits at pedestrians' height can be enhanced when the vertical greening facilities are placed along podium than tower heights. Lastly, practicable urban planning recommendations were presented for the attention of urban planners and landscape architects. 为改善户外热环境、减少室内能耗，建议应用包括外立面绿化在内的被动技术。在香港这样的高密度城市，建筑外表面积远大于屋顶与地表面积之和，为绿化提供了一个大型的垂直表面平台。但关于这种绿化栽培方式的温度效益、特别是在社区规模的温度效益，还很少有科学证据可兹证明。因此，本研究旨在利用源于经过验证的ENVI-met模型模拟的结果来提供此类证据。本文还通过参数研究法来了解外立面绿化的数量和位置。此类外立面绿化是出于降温和改善不同密度社区温度舒适性的潜在需要。模型验证结果揭示了建筑外表面温度、气温、相对湿度和建筑外墙发出的长波通量的适用建模方式。经过参数研究，我们发现，在香港高密度的环境下，必须对30-50%的建筑外表面积进行绿化处理，从而有可能将日间和夜间气温降低1°C，同时将日间行人的温度舒适性提升至少一个级别。我们同时明确，在中低密度的城市环境中，也需要增加外表面绿化率来获得类似的温度效益。同样，如沿着矮墙而不是在楼顶高度设置垂直绿化，可增强人行道高度的温度效益。最后，我们提出了若干可行的城市规划建议，以期获得城市规划部门与景观建筑师的注意。