A state-of-the-art headquarters for China CITIC Bank designed by Foster + Partners is starting to rise along the banks of the Qian Tang Jiang river in Hangzhou. The building, designed in collaboration with East China Architectural Design Institute, will serve as a high-tech landmark in a new business district that is taking this ancient city into the 21st century.

Construction workers broke ground for the project in March, 2011 and are now sinking pilings for the foundations of the 63,000 square-meter, 20-story steel structure.

The design of the 100-meter-high building is dominated by a bronze-colored diagrid lattice wrapping around its interior office spaces. Gross areas are maximized within the design's compact rectilinear footprint. The building's floor plates "split" as they rise, to create an enormous south-facing atrium and provide views out over a front plaza, the river, and the landscape beyond. At the base of the tower a 30-meter high ŒA' frame structure stretches 72 meters across the plaza level to create a dramatic entrance.

"Steel reduced the need for complex (concrete) formwork, enabled the fabrication of the node details and created the long span floor beams," said Loretta Law, a partner at the firm, "It also allowed us to easily integrate building services and speed up construction."

The firm claims that these integrated services have been made as sustainable as possible, with the diamond-shaped central atrium encouraging natural "stack" ventilation during the less climatically extreme mid-seasons. Law added that, "The design combines a high-performance envelope with active elements - such as grey water recycling, photo-voltaic panels on the roof, and efficient mechanical equipment that reduces energy use." The firm is also using building materials sourced locally to lower the project's embodied energy. To help make the stack-effect-ventilation strategy work, Foster + Partners wrapped the building's upper floors with tiered sky-gardens and topped off the tower with a winter garden and mezzanine where meeting rooms and a VIP Club offer excellent views over the city.