The aluminum louvers of the Zhengzhou Greenland Plaza were designed to capture the light from light-emitting diodes (LED) at night, creating a glowing effect. SOM © Si-ye Zhang
Zhengzhou Greenland Plaza rises from a peninsula in a man-made lake, the glowing centerpiece of a new financial district in the city.
February 5, 2013—In Zhengzhou, China, home to 8.6 million people, a sweeping new financial district bustles between the city center and the Zhengzhou Xinzheng International Airport. An empty field just five years ago, the new district has a striking centerpiece in the form of a 240 m tall, louvered tower that rises from a peninsula in a man-made lake, providing expansive views of the city.
The 60-story tower was designed by Skidmore, Owings & Merrill LLP (SOM) with headquarters in Chicago, for Shanghai Greenland Group Co., Ltd., in Shanghai. The mixed-use structure will include a 20-story Marriott hotel atop 40 stories of primarily office space, with some retail space.
The building design is based on a Greek column, the structure actually tapering slightly at the top and bottom, according to Ross Wimer, FAIA, a design director at SOM. Engineers found that the taper—chosen for grace and balance—actually improves how the loads are carried. The structure employs an aluminum and glass curtain wall system.
“Hanging off of [the façade] is a screen of extruded aluminum louvers,” Wimer says. “The louvers ... cut glare coming in and they keep heat off the façade so it allows the building to perform better in summer. The shape of these louvers also allows you to bounce some of that sunlight onto the ceiling of the space, so you can have higher-quality daylight inside the space.”
The aluminum louvers, painted white, incorporate gaps that provide the building’s occupants with unobstructed views. They also serve another critical function: because the building serves as the centerpiece of the new district, the developer placed a high premium on lighting it dramatically at night, Wimer says.
“The lighting strategy was very important to them because they wanted to mark the center of the new city, like the effect of the Eiffel Tower in Paris,” Wimer says. “One of the problems you have with illuminating a glass building is there is no surface for the light to project onto.
“This surface of louvers is really effective at catching the artificial light,” Wimer adds. “By night there is a series of LED (light-emitting diode) fixtures that light up the surface of the louvers. The profile of those louvers has been adjusted to maximize the way they catch the light from below.
“The idea was to make the tower transform from day to night. The glow is very consistent across the surface of the whole building. By day you see a delicate screen of louvers, by night those metal sunshades allow the tower to have a presence like a paper lantern,” Wimer says.
The building employs a composite structural system, with steel framing encased in concrete, according to Wimer. The concrete provides both fireproofing and load bearing capacity to the frame. The composite system is less expensive than an exclusively steel frame and quicker to build than an exclusively concrete frame.
Developers placed a high premium on the ability to light the
building at night. The LED lights create a glowing effect on the
aluminum louvers, giving the building the appearance of a lantern.
SOM © Si-ye Zhang
The Marriott hotel will feature a dramatic 20-story atrium with a glass skylight. SOM designed a massive 40 ft steel and polished aluminum heliostat reflector for the roof that concentrates and directs more daylight down into the atrium. Creating the atrium provided a challenge.
“Some of the complexity in this building had to do with getting the structural grid and the core elements to work going up through the different uses in the tower,” Wimer says. “At the top there is a large atrium in the hotel. We carried up a number of the shear walls from the office core along the edges of the atrium so the stiffness of the tower is maintained throughout its height.”
The climate in Zhengzhou is similar to that of Chicago or New York City, with extremes of temperature and a temperate spring and autumn. To take advantage of these mild periods, the building has operable windows to bring fresh air into the space.
China’s air quality concerns probably won’t become an issue with the window operations because air quality there is worst in summer and winter—times when residents are the least likely to want an open window.
Wimer says it was amazing to work on the project and see a financial district develop so quickly. “Not so long ago this was agricultural land,” Wimer says. “There is a subway system that comes in here, a whole new highway system. And all of the infrastructure is sized for the new development. By creating an ‘edge city’ many of the problems of increasing the density within the center of large older cities are avoided….It is very exciting to see a new city grow as rapidly as this one has.”
The office portion of the building was completed in late 2012, and occupants are currently moving into the high-profile tower. Finishing touches are being placed on the hotel portion of the building, scheduled to open in the spring.