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LEAF Awards 2013 Winner: Sliced Porossity Block in Chengdu
Mixed-Use Building of the Year
Steven Holl Architects, CapitaLand Raffles City, Chengdu, China
In the centre of Chengdu, China, at the intersection of First Ring Road and Ren Ming Nam Road, the Sliced Porosity Block forms large public plazas with a wealth of hybrid functions. Creating a metropolitan public space instead of object-icon skyscrapers, this three-million-square-foot project takes its shape from its distribution of natural light. A sunlight exposure pattern creates precise geometric angles that slice the exoskeletal concrete frame of the structure with glass. The building is constructed from white concrete, organised in 6ft-high openings with earthquake diagonals as are required by law.
The large public space framed in the centre of the block takes the form of three valleys inspired by a poem of the city's greatest poet Du Fu (713–770), who wrote, 'From the northeast storm-tossed to the southwest, time has left stranded in Three Valleys.' The three plaza levels feature water gardens based on concepts of time: the Fountain of the Chinese Calendar Year, the Fountain of Twelve Months and the Fountain of Thirty Days. These three ponds function as skylights to the six-storey shopping precinct below.
Establishing human scale in this metropolitan rectangle is achieved through the concept of ‘micro-urbanism’, with double-fronted shops open to the street as well as the shopping centre. Three large openings are sculpted into the mass of the towers as the sites of the Pavilion of History, the Light Pavilion and the Local Art Pavilion.
The Sliced Porosity Block is heated and cooled with 468 geothermal wells and the large ponds in the plaza harvest recycled rainwater, while the natural grasses and lily pads create a natural cooling effect. High-performance glazing, energy-efficient equipment and the use of regional materials are among the other methods employed to reach the LEED Gold rating.
LEAF Awards jury statement
This scheme for the new Raffles City district in the fast developing city of Chengdu is a hybrid of different functions. Its geometry results from required minimum daylight exposure to the surrounding urban fabric prescribed by code and calculated by the precise geometry of sun angles. The large public space framed by the block is formed into three valleys inspired by a 7th century poem of Du Fu. In some of the porous openings parts different buildings are inserted. The judges approved of the architects’ bold yet discerning design strategy coupled with a mature micro-urban plan for a new terrain of public space in the form of an urban terrace on the metropolitan scale of Rockefeller Center, sculpted by stone steps and ramps with large pools that spill into stepped fountains. Trees, plantings, benches and roof gardens are positioned close to cafes.
The design aims to be a sustainable role model, and responds very well to the need to achieve new levels of green construction in Chengdu, with a complex that is heated and cooled geothermally by 400 wells. The large podium ponds harvest recycled rainwater with natural grasses and lily pads creating a cooling effect.