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Winds of change

By Binyi Liu and Dongxue Wei
Research into how design can affect microclimate has led to the gathering of data and then to testing in a live project.

With the challenge of climate change, one of the most important related issues for human settlements is the outdoor microclimate as it affects human activities. Research on Microclimate Responsive Design Theory and Method of Landscape Architecture in Urban Livable Environment (2014–2018) is the first and only key project supported by the National Natural Science Foundation of China (NSFC in the field of Chinese landscape architecture. The research focuses on the coupling of three core landscape microclimatic issues, (1) system functions including wind, water and heat; (2) elements and spatial forms; (3) the perception of landscape microclimate which includes theory, method, technology, and case survey and verification (Fig.1). Based on two climatic zones as Southeast China (hot summer/wet winter wet climate zone) and Northwest China (hot summer/ wet winter dry climate zone), 3 kinds of urban green space (urban square, street and waterfront and residential area) and 9 types within macro scale (5 ha), medium scale (1–5 ha), and micro scale (<1 ha) are used.

Since January 2014, more than 40 researchers (professors and PhD and postgraduate students) have devoted themselves to this research, conducting around 100 microclimate experimental tests in urban green spaces such as urban squares, streets and waterfronts: covering residential areas on the scale of 1000m2–100000m2 in downtown Shanghai (Figs. 2, and 3). With three years’ worth of research now complete, we have learnt the following about localized wind environments: 
In terms of the formative elements of landscape microclimate at urban squares, the research team obtains wind environment data from different test points on the square from a small meteorological station (Fig. 4, Fig. 5, Fig. 6) to quantify the correlation between the vertical interface of the square space and wind environment. The research finds that: (1) the vertical interface in the urban square can effectively reduce the wind speed and stabilize the wind direction; (2) the wind speed at some horizontal direction in the square space may gradually intensify with the increase of distance between such a point and the vertical interface. 

In terms of adapting the micro-climate by changing the spatial form and spatial elements in the urban square, the research addresses the spatial model of Shanghai Century Square by using climate simulation software to further quantify the effect of vertical interfaces of different types on the wind environment at the square space. The research found that when the included angle between the square’s vertical interface and the wind direction is increased gradually, its reduction effect on the wind speed increases gradually at first and then weakens. When the included angle is 90°, the wind speed reduction effect is the greatest (Fig. 7). In terms of the urban square microclimatic adaptive physical assessment and perception assessment, the research (based on the actual physical measurement for 21 days in summer, autumn and winter as well as 878 users’ questionnaires) analyzed people’s thermal sensation and thermal preference (Fig. 8) in the square space with sufficient shade. This research found that: (1) in summer, 80% of interviewees prefer a reduction in the air temperature and an increase in wind speed. In both autumn and winter, the majority of people prefer an increased temperature, reduced wind speed and intensified solar radiation (Fig. 9); (2) in both autumn and winter, the residents’ wind speed preference correlated positively with the air temperature with a correlation of 0.739. 

The research also applied the concept and methodology of landscape microclimatic adaptive design to a real urban public space construction project which included landscape, hydrology, urban infrastructure, transportation, bridge, architecture and urban planning. Called the Cultural Landscape Planning and Design project of the Sino-Arab Axis in Yinchuan, Ningxia Province, the project covers 280ha. Its chief designer was Binyi Liu and the construction cost was 0.3 billion RMB (approximately £34,600,000). The research is using this live project as a case study and experiment. In March, 2016, with microclimatic data collected by experimental tests during late winter, the research team found that the north wind was dominant on the site, with an average of force 2 on the Beaufort Wind Scale, and a fastest gust of force 3. The maximum wind speed in winter is the crucial issue in planning and design. In terms of landscape climatic adaptive design intelligence in classic Chinese landscape gardening, one takes advantage of gardening elements such as landscape topography and garden walls to facilitate ventilation by the south wind and to block the north wind (Fig. 11, Fig.12.) We used the climatic simulation software to verify the wind blocking and heat-raising effect of having landscape walls of varing thicknesses, height and angles. This project is currently under construction and will be completed by 2019. After construction, the research team will conduct experimental tests on the site to analyse on-site climatic variance and improvement before and after construction. 

Research on landscape micro-climatic response and adaptation in urban open and green space possesses huge potential benefits and research value for human settlement, particularly with the challenge of climate change in the future, and also for promoting and maybe changing the methods and practice of landscape planning and design. The research will also promote the science and rationale behind Chinese landscape architecture. At a more profound level, the research achievements will further enrich the world landscape microclimate adaptive research database and play an important role in global and regional research.

(All figures and diagrams produced by Binyi Liu’s research team).
Binyi Liu, Ph.D. and Professor, Correspondent author, Chairman of landscape architecture discipline and profession Committee, College of Architecture and Urban Planning, Tongji University; Convener of Landscape Architecture Discipline Review Group of the Academy Committee of State Council, China; Deputy Director of Education Committee of Professional Bachelor Degree of Landscape Architecture, China;member of urban design expert committee of Department of Construction of China; member of landscape architecture expert committee of Department of Construction of China;Vice President of Shanghai Landscape Architecture Society (Shanghai 200092) Email: [email protected]

Dongxue Wei, Landscape architecture PhD candidate at Department of Landscape Studies Tongji University. (Shanghai 200092).

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