TY - JOUR
T1 - Investigation of extensive green roof outdoor spatio-temporal thermal performance during summer in a subtropical monsoon climate
AU - Yin, Haiwei
AU - Kong, Fanhua
AU - Dronova, Iryna
AU - Middel, Ariane
AU - James, Philip
N1 - Funding Information:
The research was supported by the Key Project on Intergovernmental International Science, Technology and Innovation (STI) Cooperation of China's National Key Research and Development Program (No. 2017YFE0196000), and the National Natural Science Foundation of China (Nos. 51878328, 31670470, 51478217). The authors thank Jiayu Chen, Junsheng Li, Hailong Xu, Wenbin Xu, Baogang Shi and all other members who helped to conduct the field surveys.
Funding Information:
The research was supported by the Key Project on Intergovernmental International Science, Technology and Innovation (STI) Cooperation of China's National Key Research and Development Program (No. 2017YFE0196000 ), and the National Natural Science Foundation of China (Nos. 51878328 , 31670470 , 51478217 ). The authors thank Jiayu Chen, Junsheng Li, Hailong Xu, Wenbin Xu, Baogang Shi and all other members who helped to conduct the field surveys.
Publisher Copyright:
© 2019
PY - 2019/12/15
Y1 - 2019/12/15
N2 - The thermal performance of green roofs is usually site-specific and changes temporally. Hence, thermal performance evaluation is necessary to optimize green roof design and its cooling effect. In this paper, we evaluated the outdoor spatio-temporal performance of a full-scale extensive green roof (EGR) in Nanjing, China throughout a summer at three heights (30, 60and 120cm). We found the EGR exhibited an overall slight diurnal cooling effect at all three heights (−0.09, −0.23, and − 0.09 °C, respectively), but there was an obvious warming effect at a couple of specific hours during daytime. Especially on sunny days, the maximum warming effect at all three heights was 1.59, 0.59, and 0.38 °C, respectively. During the night, the EGR had a pronounced cooling effect of −0.63, −0.40, and − 0.15 °C, respectively. Among the weather scenarios, sunny days had the highest impact on the EGR's thermal performance, while effects were less pronounced on cloudy and rainy days. The average range of hourly air temperature difference at 30 cm between EGR and a bare roof on selected days was 4.02 (sunny), 2.67 (cloudy), and 0.74 °C (rainy). The results of multiple-regression analyses showed strong and significant correlations of air temperature difference between the EGR and a bare roof with differences in relative humidity, net radiation, several measures of soil and surface temperature, and soil moisture as well as average solar radiation, air temperature and wind speed. The results implied that both the components of the EGR, such as green vegetation and the soil substrate layer, and the microclimate created by the EGR can feed back and contribute to the thermal performance of an EGR. Through this full-scale EGR research in a subtropical monsoon climate, we provide the scientific basis and actionable practices for green roof planning and design to alleviate the urban heat island effect towards designing climate-resilient cities.
AB - The thermal performance of green roofs is usually site-specific and changes temporally. Hence, thermal performance evaluation is necessary to optimize green roof design and its cooling effect. In this paper, we evaluated the outdoor spatio-temporal performance of a full-scale extensive green roof (EGR) in Nanjing, China throughout a summer at three heights (30, 60and 120cm). We found the EGR exhibited an overall slight diurnal cooling effect at all three heights (−0.09, −0.23, and − 0.09 °C, respectively), but there was an obvious warming effect at a couple of specific hours during daytime. Especially on sunny days, the maximum warming effect at all three heights was 1.59, 0.59, and 0.38 °C, respectively. During the night, the EGR had a pronounced cooling effect of −0.63, −0.40, and − 0.15 °C, respectively. Among the weather scenarios, sunny days had the highest impact on the EGR's thermal performance, while effects were less pronounced on cloudy and rainy days. The average range of hourly air temperature difference at 30 cm between EGR and a bare roof on selected days was 4.02 (sunny), 2.67 (cloudy), and 0.74 °C (rainy). The results of multiple-regression analyses showed strong and significant correlations of air temperature difference between the EGR and a bare roof with differences in relative humidity, net radiation, several measures of soil and surface temperature, and soil moisture as well as average solar radiation, air temperature and wind speed. The results implied that both the components of the EGR, such as green vegetation and the soil substrate layer, and the microclimate created by the EGR can feed back and contribute to the thermal performance of an EGR. Through this full-scale EGR research in a subtropical monsoon climate, we provide the scientific basis and actionable practices for green roof planning and design to alleviate the urban heat island effect towards designing climate-resilient cities.
KW - Experimental analysis
KW - Extensive green roof
KW - Outdoor cooling effect
KW - Subtropical monsoon climate
KW - Thermal performance
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U2 - 10.1016/j.scitotenv.2019.133976
DO - 10.1016/j.scitotenv.2019.133976
M3 - Article
C2 - 31470331
AN - SCOPUS:85071271125
SN - 0048-9697
VL - 696
JO - Science of the Total Environment
JF - Science of the Total Environment
M1 - 133976
ER -