The International Horticultural Expo becomes instigator and core for the redevelopment of a large area between the airport and the ancient city center of Xi’an, known as the home of the Terracotta Army and business centre of the vast Chinese interior. Plasma Studio with collaborators GroundLab won this invited international competition with a radical self-sustainable vision for the future: Flowing Gardens creates a consonant functionality of water, planting, circulation and architecture into one seamless system.
The proposal comprises of a 5000 sqm Exhibition Hall, a 4000 sqm Greenhouse and a 3500 sqm Gate Building sitting in a 37 ha landscape that will house the International Horticultural Expo and a park for Xi’an City as legacy. The Expo will open in 2011, receiving approximately 200,000 visitors a day.
Flowing Gardens unfolds many sinuous paths, creating a network of intermingling circulation, landscape and water. The given topography and its existing slopes were used to draw out the paths in a way similar to how roads ribbon around a mountain, negotiating steepness with gradients. These paths vary in width ranging from main walkways and arteries to towpaths. The patches between these paths become the zones for various planting types and wetland areas, which retain a quality of ease of maintenance.
The three projected buildings, located at the intersections of the major pathways are developed as the nodal articulation and intensification of the landscape.
Landscape. The project proposes a hybrid of both natural and artificial systems. These two opposing systems are brought together in a synergy of waterscapes.
Considering the amount of water needed for irrigation, the project seeks to introduce various technologies and designs found in nature, yet customized by man to suit his specific needs.
Rainwater is collected and channeled into wetland areas. There, natural plants and reed beds are used to clean and store the water to be dispersed and used for irrigation. These natural systems
are integrated into the landscape as wetlands and ponds, which can also be enjoyed by the visitors as points of tranquility and oasis.
The water cycle begins to become more complex with the introduction of grey and black water treatment.
We propose to make use of the initial investment and organization during the exhibition to set up a system which becomes autonomous in function and character. The gardens transform the two conditions of artificial and natural into a sustainable system that becomes more and more maintenance-free once the exhibition is over, allowing the park to become a new model, or paradigm, within the horticultural industry.
The park creates a variety of scales in association with very specific planting, surfacing and lighting, thus providing a gradient of experiences that ranges from the very intimate with semi-enclosed,
shaded, self contained, one to- one spaces, to the very public with communal plazas formed by wider
pedestrian paths with full sun exposure and a direct visual link to the main hiatus on the site.
The Gate Building The Gate Building operates on the level of infrastructure and fulfils the role of bridging over the main road that dissects the site. Thus it channels the visitors from the entry plaza, where they congregate and orient themselves after having entered into the Expo and sets them into a definite direction. By bringing them up to +7.00 m the bridge offers vantage points from where to gain an overview of the different zones of the Expo ahead.
Functionally, the bridge needs to have two lanes for incoming and outgoing traffic. Naturally, these flows are very uneven and change greatly between the beginning and end of the day. Taking the idea from the London Underground escalators we devised the bridge to have three lanes, where the middle lane switches from the incoming direction in the morning to outgoing later in the day.
The three bands read as interwoven braids, and together with a trellis roof structure give the appearance of bands of landscape peeling off and turning into structure. Between the three bands are green areas and a water feature for visitors to stop, have a rest and enjoy the view. Above them an open trellis steel structure forms a shading device that becomes overgrown with climbing plants forming a green roof, and suggesting to distant onlookers the theme of the Expo.
For this lightweight roof, we developed together with Arup an innovative tensegrity structure that appears as beams seemingly free-floating in space.
Exhibition Centre The building is located on the edge of the lake as the endpoint to the central axis that starts with the Gate Building, as well as the starting point for the crossing of the water by boat. It ties in with the series of piers that read as the landscape jetting out into the water. The built volume is interwoven with the articulated ground, producing continuities on many levels so that landscape and building become completely integrated. From this stems the organization of the building massing as three parallel volumes within the landscape, flowing through and underneath, leading to the piers. The volumes themselves hover as cantilevers over the lake. The fluid experience of passing through the landscape continues inside, where all zones are generous and interconnected. The employment of ramps enable visitors to move up to a mezzanine level and out onto the roof of the building. Through its materiality the building again manifests itself as an extension of the ground with its floors and interior walls made from high quality concrete. Bronze, as a locally specific material, wraps the buildings partially while bands of greenery cover it like a tessellated net. The roofs are structured as a series of folds - these can be experienced as articulated ceilings that introduce a finer grain into the otherwise simple and minimal spaces.
Green House The Greenhouse is defined as a precious crystal, semi-submerged in splendid isolation. Visitors need to cross the lake by boat to then walk up to it from the shore. More than the other two buildings, the greenhouse blends into the hillside.
One enters the building through a prolonged cut, literally being scooped up by the ground then emerging within a lightfilled cavernous reception space.
From here the visitor transgresses along a tessellated mesh of paths through three different climatic zones with corresponding plant environments. The greenhouse has a horseshoe plan creating one loop that changes radically in
section to accommodate a sequence of different planting and spatial conditions. With the ground inside and outside gradually changing in relation to each other, the visitor is experiencing sequences of visual enclosure alternating with long vistas out and across. The horseshoe shape generates an inner courtyard, making the outside space the natural centre of the building. This courtyard becomes dissected by two paths that continue to slope up to pass over the roof, at the apex of the greenhouse and further into the landscape. This creates a three-dimensional interweaving of interior and exterior circulation, of building and landscape.