Evaluating the impact of urban green space and landscape design parameters on thermal comfort in hot summer by numerical simulation Shibo Sun a, 1 , Xiyan Xu b, c, *, 1 , Zhaoming Lao d , Wei Liu a , Zhandong Li a , Ester Higueras García e , Li He b , Jianning Zhu a, ** a College of Landscape Architecture, Beijing Forestry University, Beijing 100083, China b School of Renewable Energy, North China Electric Power University, Beijing 102206, China c Faculty of Science, University Autonoma of Madrid, Madrid 28049, Spain d Zhongshan Meteorological Service, Zhongshan 528400, China e Escuela T ecnica Superior de Arquitectura, Universidad Polit ecnica de Madrid-UPM, Madrid 28040, Spain article info Article history: Received 25 April 2017 Received in revised form 6 July 2017 Accepted 7 July 2017 Available online 8 July 2017 Keywords: Green space Thermal comfort ENVI-met Landscape design Landscape parameters Vegetation Beijing abstract Urban green spaces (UGS) can help to moderate the urban heat island effect and thus thermal comfort through the impact of landscape design parameters with regard to the land cover features. The current work investigates the thermal comfort modification potential of a long belt-shaped park (around 9 km) in Beijing and the effects of its landscape parameters using numerical simulation. Holistic spatial and temporal distribution scenarios of thermal comfort of the park are obtained in terms of physiological equivalent temperature (PET). The UGS covered regions generally exhibit better thermal comfort level, but deteriorating phenomenon is also found at some uncovered sites in the park due to the solar- radiation and enhanced reflection effect. At 14:00 h, the mean reduced PET (△PET m ) by UGS are around 2  C with the maximum and minimum value being 15.6  C and 8.4  C, respectively. Regression analyses show that the most significant influential factor on the moderation of thermal comfort is the higher trees, while the hardened ground exhibits a negative effect. The outcome of the current work provides detailed knowledge on the benefits of UGS and gives suggestions for urban landscape planners and policy makers to improve urban thermal comfort. © 2017 Published by Elsevier Ltd. 1. Introduction Rapid urbanization brings not only convenient modern lifestyles in terms of functional centralization, but also continuous deterio- ration of urban environment such as the urban heat island (UHI) effect which can reduce the urban thermal comfort [1]. Increasing the percentage of urban green space (UGS) and a better arrange- ment of the landscape parameters can ease this concern effectively, as argued by scholars during the last decade [2]. Those landscape parameters include vegetation, water body, hardened ground (walking path and plaza) and building (shading devices and other buildings). The vegetation components of the UGS like lawn and trees allow cooling effect by transpiration process through vapor- ization of the water discharged from the leaves [3e5]. Apart from that, trees can also provide a cool shading area below the canopy by interrupting the direct solar-radiation, so that the thermal comfort sensation can be improved in both the covered region and adjacent surroundings [6e12]. Masmoudi et al. [7] reported that the pres- ence and orientation of the vegetable masses are fairly significant parameters impacting the surrounding microclimate. Perini et al. [13] investigated the cooling effect of vegetation where a difference was found with respect to the amount of green area and vegetation types. They also found that vegetation was more effective in the microclimate with higher temperatures and lower relative hu- midity (RH) values. Specific study revealed that the transmissivity of total and direct solar radiation through crown of street trees could be significantly reduced within the foliated area [14]. Very recently, Morakinyo et al. [4] studied the thermal comfort * Corresponding author. School of Renewable Energy, North China Electric Power University, Beijing 102206, China. ** Corresponding author. E-mail addresses: yorkxxu@gmail.com (X. Xu), blzjn@vip.sina.com (J. Zhu). 1 Author contributions: These authors contributed equally. Contents lists available at ScienceDirect Building and Environment journal homepage: www.elsevier.com/locate/buildenv http://dx.doi.org/10.1016/j.buildenv.2017.07.010 0360-1323/© 2017 Published by Elsevier Ltd. Building and Environment 123 (2017) 277e288