A Horizontal Skyscraper Greens the Land: Steven Holl fuses architecture and landscape to make one of the most sustainable buildings in China.
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Three decades of breakneck economic development have made China one of the world’s great polluters, but a new green ethos is beginning to take root in the Land of 1.3 Billion People. Not only is the Chinese government moving to reduce carbon dioxide emissions and encourage alternative energy production, but a growing number of Chinese companies are demonstrating a strong commitment to sustainable design. A leader of this movement is China Vanke, the country’s largest residential developer and a company that has hired innovative architects from China and abroad to design a number of projects. Its founder and chairman, Wang Shi, has made a name for himself not only as an entrepreneur, but as a mountain climber (he has reached the summit of Mt. Everest twice) and dedicated environmentalist. So it is not surprising that Vanke wanted its headquarters in Shenzhen to embody the highest green values.
Designed by Steven Holl Architects, which completed its Linked Hybrid residential complex in Beijing in 2009 and is busy working on large-scale projects in Chengdu, Hangzhou, and Nanjing, the 1.14-million-square-foot Vanke headquarters hovers 50 feet above the ground—a “horizontal skyscraper” that is a bit longer (1,310 feet) than the Empire State Building is tall (1,250 feet). By raising the building off the land (on eight supporting structures clad in back-lit, translucent glass), the architects were able to turn almost the entire site, including the area under the building, into a park open to the public. And by planting the roof, they created about the same amount of green space on the site as had been there before. “Our aim was to use a private development to create a public park,” states Steven Holl.
Holl and his Beijing-based partner Li Hu approached the project, which was one of the first LEED Platinum buildings in China, as a seamless combination of architecture and landscape. Built on reclaimed land that forms part of the city’s stormwater management system, the complex—which includes condos, a hotel, and a conference center, in addition to offices—sits on a lagoon that functions as a bio-swale/retention pond connected to adjacent creeks. The architects redesigned a waterfront retaining wall as a planted estuary, establishing a restorative ecology that minimizes run-off, erosion, and environmental damage. (The LEED status applies only to the office portion, which was completed first.)
A series of courtyards, sunken gardens, ponds, and planted mounds creates a circulatory system that regulates and redistributes stormwater throughout the site. In areas where pavement was required, the architects specified permeable materials such as local river stones, gravel, open-joint stone pavers, grass-crete, and compressed sand pavers to absorb water and naturally filter it. “The landscape is really a machine for cleaning the water and tempering the climate,” states Holl.
Because the building sits above the ground, breezes from the nearby South China Sea flow underneath it and cool it. The building creates temperate micro-climates in a part of the world known for hot, moist weather, explains Holl. Raising the structure also gives the spaces inside better views of the sea (to the south) and mountains (to the north). The building’s long, narrow floor plate ensures that office workers inside can rely mostly on daylight for illumination. Large operable windows 6.6 feet wide reduce dependence on mechanical ventilation, especially during cooler months (November to March) when natural ventilation can take over 60 percent of the time, estimate engineers at Transsolar. Operable windows can also cut electrical energy consumption annually by about one-quarter or 5 kWh per square meter.
“Dealing with the hot and humid climate and the small daily temperature variation was the biggest challenge for us,” states Peter Voit, the partner in charge for Transsolar. “But we did detailed calculations of shading performance and devised a system of fixed louvers and operable windows that achieves very comfortable conditions with natural ventilation during the winter season,” explains Voit.
High-performance glass, with two low-e coatings and a custom-designed system of perforated aluminum louvers, protects the curtainwall from the full impact of the sun. To get the most protection while maximizing daylight and views, the architects designed a different elevation for each of the building’s 26 faces—adjusting the amount of fixed and operable louvers and the size of the perforations in the louvers to the orientation of the sun. A computer-and-sensor-controlled system automatically tunes the operable louvers to the movement and intensity of the sun. When closed, the louvers reduce solar heat gain by 70 percent, while allowing 15 percent of daylight to filter through the perforations. By suspending the louvers beyond the glass face of the building, the architects created a convective stack effect that draws cool air from the underside of the structure while pulling hot air out from the top.
To reduce dependence on conventional energy sources, the architects installed 15,000 square feet of photovoltaic panels on the building’s roof. They estimate that these solar cells will provide 12.5 percent of the headquarters’ total electricity needs.
Throughout the project, Holl’s team specified products made from renewable materials. For example, the architects used bamboo for doors, floors, and furniture, and carpet tiles with vinyl backing made from recycled carpet and manufacturing waste. All paints, finishes, and adhesives in the building have either few or no VOCs.
To conserve potable water, the building is equipped with low-flow, highly efficient plumbing fixtures and waterless urinals. In addition, dual-flush toilets use recycled graywater. Outdoors, rainwater filtered by the bio-swale system is used to irrigate the grounds.
Holl worked with engineers at the China Academy of Building Research to design an innovative structural system that combines a high-strength concrete frame with the kind of steel cable-stay technology most often used on bridges. The solution eliminated the need for large trusses that would have impaired views from office areas and disrupted interiors more than the angled cables that were used. These cables transmit the building’s vertical load to key structural elements such as reinforced-concrete cores, walls, and columns and then to the foundation.
Like Holl’s Linked Hybrid in Beijing, the Vanke headquarters combines different functions in one complex—an 86,000- square-foot conference center tucked into green-roofed mounds at its base, 214,000 square feet of hotel space, and 211,000 square feet of condominium apartments. Parking is mostly underground. Because the office, condo, and hotel functions all occupy one long building, the scheme offers flexibility in terms of the amount of space allocated to each segment.
While some people question China’s commitment to sustainability, Holl says all of his Chinese clients have asked for the greenest buildings possible. “In other parts of the world, clients want to nickel-and-dime sustainability, questioning every expenditure,” states the architect. “Chinese clients aren’t thinking that way. They’re thinking of building the future.”
Clifford A. Pearson is an editor at Architectural Record.