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Journal of ZheJiang University (Engineering Science)  2020, Vol. 54 Issue (10): 1993-2000    DOI: 10.3785/j.issn.1008-973X.2020.10.017
Effect of high-albedo roofs on urban heat island and air-conditioning energy consumption
Jin LIANG1(),Kun LUO1,*(),Qiang WANG1,Xu-chao YANG2,Jian-ren FAN1,Jun-xi ZHANG1
1. State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
2. Ocean College, Zhejiang University, Zhoushan 316000, China
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The city of Hangzhou, where high temperature occurred frequently in summer, was selected as a typical high-temperature period of 22—28 July 2017 in order to analyze the mitigation effects of the high-albedo roofs, the urban cooling technology, on the urban heat island in summer and its impact on the cooling load of air-conditioning. The numerical simulation was performed using the weather research and forecasting model (WRF), coupled with the building energy model based on multi-layer building environment parameterization (BEP+BEM). Results show that the roofs with an albedo of 0.85 can reduce the average daily temperature of the urban area by 0.37 °C, while the urban heat island intensity decreases by 0.21 °C. The urban heat island is alleviated to some extent, and the air-conditioning refrigeration load is reduced by about 5.3%. High-albedo roofs show better cooling and energy-saving effects in buildings-intensive business districts than in low-density residential areas. The roof albedo is negatively correlated with the urban 2 m temperature and air-conditioning energy consumption.

Key wordshigh-albedo roofs      urban heat island      air-conditioning energy consumption      weather research and forecasting model (WRF)      building energy model based on multi-layer building environment parameterization (BEP+BEM)     
Received: 18 September 2019      Published: 28 October 2020
CLC:  P 49  
Corresponding Authors: Kun LUO     E-mail:;
Cite this article:

Jin LIANG,Kun LUO,Qiang WANG,Xu-chao YANG,Jian-ren FAN,Jun-xi ZHANG. Effect of high-albedo roofs on urban heat island and air-conditioning energy consumption. Journal of ZheJiang University (Engineering Science), 2020, 54(10): 1993-2000.

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为了研究高反照率屋顶这一城市降温技术对夏季城市热岛效应的缓解作用及对空调制冷负荷的影响,以夏季高温频发的杭州市为例,选取2017年7月22日—28日作为典型高温时段,采用中尺度天气预报模式(WRF)耦合考虑建筑物能量交换的多层城市冠层参数化方案(BEP+BEM)进行数值模拟. 结果表明,反照率为0.85的屋顶使城市区域日均降温0.37 °C,城市热岛强度减小0.21 °C,城市热岛效应得到了一定程度的缓解,空调制冷负荷降低约5.3%;建筑物密集的商业区的降温和节能效果均优于低密度居住区;屋顶反照率与城区2 m气温及空调能耗均线性负相关.

关键词: 高反照率屋顶,  城市热岛,  空调能耗,  天气预报模式(WRF),  BEP+BEM方案 
Fig.1 Three layers of nested domains and land use types of d03 domain for WRF model
土地类型 建筑平均高度类型 wb / m ws / m αs,w dp /(人·m–2) Tac/K COP tac / h
LR 5 m, 15%1);10 m, 70%;
15 m, 15%
13 30 0.2 0.01 298 3.5 24
HR 10 m, 20%;15 m, 60%;
20 m, 20%
17 25 0.2 0.01 298 3.5 24
CM 15 m, 10%;20 m, 25%;
25 m, 40%;30 m, 25%
20 20 0.2 0.02 297 3.5 24
Tab.1 Configurations of simulation cases (CTRL, ALB1, ALB2, ALB3)
Fig.2 Simulated and observed 2 m temperature、relative humidity and 10 m wind speed
Fig.3 Daily change of mean and difference of parameters in CTRL and ALB3 urban areas
Fig.4 Daily change of air-conditioning energy comsuption and sensible heat realsed by air-conditiong in CTRL and ALB3 urban areas
Fig.5 Comparison of air-conditioning energy consumption of CTRL and ALB3
城市区域类型 案例名称 t / °C UHII / °C WS10 /(m·s?1 EAC /(W·m?2
CM CTRL 37.60 2.26 2.43 41.48
CM ALB3 37.10 1.93 2.08 39.88
CM ALB3?CTRL ?0.50 ?0.32 ?0.35 ?1.61
HR CTRL 37.06 1.72 2.85 19.96
HR ALB3 36.52 1.36 2.45 18.57
HR ALB3?CTRL ?0.53 ?0.35 ?0.40 ?1.38
LR CTRL 36.49 1.15 3.03 6.77
LR ALB3 36.07 0.91 2.64 6.14
LR ALB3?CTRL ?0.42 ?0.24 ?0.39 ?0.63
Tab.2 Comparison of simulation results between CTRL (control) and ALB3 (albedo is 0.85) in different urban areas in daytime
Fig.6 Comparison of 2 m temperature in nighttime and daytime in CTRL and ALB3
Fig.7 Linear relationship between different albedo and t, UHII, WS10, EAC in urban areas
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