TY - JOUR
T1 - Cooling effect of direct green façades during hot summer days
T2 - An observational study in Nanjing, China using TIR and 3DPC data
AU - Yin, Haiwei
AU - Kong, Fanhua
AU - Middel, Ariane
AU - Dronova, Iryna
AU - Xu, Hailong
AU - James, Philip
N1 - Funding Information:
The research was supported by the National Natural Science Foundation of China (No.51478217, 31170444) and Central university basic research and operating expenses of special funding. The authors thank Wenfeng Zhan, Guang Zheng and Lixia Ma for helping data processing; and thank Fengfeng LIU, Xiaojuan Wang and all other members who helped to conduct the field surveys.
Publisher Copyright:
© 2017 Elsevier Ltd
PY - 2017/5/1
Y1 - 2017/5/1
N2 - Thermal regulation is a key ecosystem service provided by direct green façades (DGFs), as vegetated walls absorb short wave radiation, reduce solar re-radiation from hard surfaces, and provide cooling due to shading and evapotranspiration. Few studies have investigated the correlation between the cooling effect of DGFs and vegetation characteristics at a fine spatial and temporal scale. This paper presents a new methodology to evaluate the cooling effect of DGFs related to fine-scale plant characteristics for hot summer days using thermal infrared (TIR) and three-dimensional point cloud (3DPC) data, through a case study conducted at the Executive Office Building on Nanjing University's Xianlin Campus, China. Results show that daily mean DGF surface temperature is significantly lower than the average bare wall surface temperature, with a maximum reduction of 4.67 °C. The cooling effect of the DGF is most obvious during midday (10:30 h to 16:00 h) and significantly decreases at night. At the pixel scale, the DGF exhibits a significant spatial variation of surface temperatures, which may be closely related to the DGF's canopy structure. Among the four vegetation indices acquired based on 3DPC data, the percentage of green coverage and the cooling effect of the DGF exhibited a linear relationship, while plant thicknesses, point density, and volume of the green façade were power function distributions. Incoming solar radiation and air temperature are the dominant independent variables in cooling effect and surface temperature fitting models. Our findings can guide DGF design to cool the thermal environment more effectively and to enhance building energy savings.
AB - Thermal regulation is a key ecosystem service provided by direct green façades (DGFs), as vegetated walls absorb short wave radiation, reduce solar re-radiation from hard surfaces, and provide cooling due to shading and evapotranspiration. Few studies have investigated the correlation between the cooling effect of DGFs and vegetation characteristics at a fine spatial and temporal scale. This paper presents a new methodology to evaluate the cooling effect of DGFs related to fine-scale plant characteristics for hot summer days using thermal infrared (TIR) and three-dimensional point cloud (3DPC) data, through a case study conducted at the Executive Office Building on Nanjing University's Xianlin Campus, China. Results show that daily mean DGF surface temperature is significantly lower than the average bare wall surface temperature, with a maximum reduction of 4.67 °C. The cooling effect of the DGF is most obvious during midday (10:30 h to 16:00 h) and significantly decreases at night. At the pixel scale, the DGF exhibits a significant spatial variation of surface temperatures, which may be closely related to the DGF's canopy structure. Among the four vegetation indices acquired based on 3DPC data, the percentage of green coverage and the cooling effect of the DGF exhibited a linear relationship, while plant thicknesses, point density, and volume of the green façade were power function distributions. Incoming solar radiation and air temperature are the dominant independent variables in cooling effect and surface temperature fitting models. Our findings can guide DGF design to cool the thermal environment more effectively and to enhance building energy savings.
KW - Cooling effect
KW - Direct green façade
KW - Plant characteristics
KW - Thermal infrared images
KW - Three-dimensional point cloud
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U2 - 10.1016/j.buildenv.2017.02.020
DO - 10.1016/j.buildenv.2017.02.020
M3 - Article
AN - SCOPUS:85014010769
SN - 0360-1323
VL - 116
SP - 195
EP - 206
JO - Building and Environment
JF - Building and Environment
ER -