Council on Tall Buildings and Urban Habitat
 

Zifeng Tower, Nanjing
Featured September 2013
Zifeng Tower was recognized as a finalist for the "Best Tall Building Asia & Australasia" Award in the 2010 CTBUH Awards Program.
Other Featured Tall Buildings

“For a tower that was the sixth tallest in the world at completion this building has received little attention. The skillful handling of the serrated façade alone makes that a travesty.”
- Antony Wood, CTBUH 2010 Awards Juror, CTBUH

Location
Nanjing
Completion
2010
Height
450m (1,476ft)
Stories
66
Primary Uses
Hotel / Office

Owner
Nanjing State Owned Assets

Developer
Nanjing Guzzi Greenland Financial Center

Design Architect
Skidmore, Owings & Merrill LLP
Associate Architect
ECADI

Structural Engineer
Skidmore, Owings & Merrill LLP
MEP
Skidmore, Owings & Merrill LLP
Main Contractor
Shanghai Construction
Other Consultants
Schindler; KONE; Dow Corning Corporation

The triangulated, serrated façade treatment is interesting, adding depth and texture to the imposing form while allowing natural ventilation throughout. Carefully sited and planned, the tower creates a “flatiron” effect—stretched to its incredible height—on one of Nanjing’s busiest intersections.

Zifeng Tower (formerly known as Nanjing Greenland Financial Center) is a mixed-use complex comprising of several buildings resting on two sites, parcels A1 and A2. Parcel A1 contains a podium connecting two towers. The taller 450m (1,476ft) tower consists of offices and hotels, and the 100m (328ft) tower contains purely office space. The shape and placement of the buildings are designed to echo the geometry of the existing roads and maximize exterior views of the city. The buildings’ composition maintains the east–west viewing corridors along East Beijing Road and provides a visual link to the nearby historical drum and bell towers.

Landscaping is a significant part of the complex as the buildings are set back from the street with several large landscaped, public open spaces. South of parcel A1, is a sunken garden that will connect to the future subway. There is also a roof garden at the top of the podium in parcel A1 to reduce the heat island effect. In addition to the ground level and podium garden spaces, the design incorporates sky gardens that wind their way up the façade, bringing the green all the way up the tower.

As one of the tallest structures in the world to date (ranked as the sixth tallest building in the world at the time of its completion by the CTBUH) and being constructed in a seismic region, enhanced design measures and performance-based evaluations were utilized in order to obtain seismic review approval for the main tower. The critical parts of the lateral system were designed for earthquake forces between two and six times more than typically required by Chinese code. Additionally, a full 3-Dimensional Non-Linear Elasto-Plastic analysis for a 2,500-year earthquake was completed to determine the structural response and serviceability. A multi-stage axial shortening, creep and shrinkage analysis was also performed to evaluate the long-term load sharing between the central core and the perimeter of the Tower through the outrigger truss system.

Figure 1. Zifeng Tower uner construction

The tower features a unique façade system, rather than a typical flush-glass curtain wall system; it is composed of offset modular panels that protrude in plan to create a distinctive texture to the building’s elevations. Each curtain wall unit is a triangle in plan and shifts a half module between each two floors. It creates a scaled effect and has a very unique visual appeal in catching the light and reflections of the city. The small edge of the triangle unit is a fixed perforated metal panel with a hidden operable panel behind it for natural ventilation and smoke exhaust. This will help to reduce mechanical ventilation energy usage during some transitional seasons. The long edge of each triangle unit consists of a high performance insulated low-E glass panel, to help to cut down the heat gain through the building façade.

Figure 2. Detail of the scaled facade

The office tower is served by floor-by-floor, variable volume, supply air handling units with variable speed drive. Four pipe fan coil units are provided for hotel guest rooms. Gas fired steam boilers and chillers, and associated water pumps are located on the first basement level. Gas service is brought into the building for the boilers and for kitchens. The fire protection system for the building consists of a zoned combination automatic sprinkler and standpipe system in accordance with regulatory requirements for a fully sprinklered high-rise building in China.

The office tower is served by two banks of seven elevators, one bank for the low-rise office levels, and one for the high-rise office levels. Two service elevators are designated as fire elevators and serve all floors of the office tower (three separate service elevators will serve all floors of the hotel).  The hotel portion of the main tower will be served by three express passenger elevators from the ground floor entrance lobby to the level 36 sky lobby, where five local passenger lifts will take guests up to the highest hotel level on 65.

Related Links
CTBUH Skyscraper Center Profile:
Zifeng Tower

Zifeng Tower was recognized as a finalist for the Best Tall Building Asia & Australasia in the 2010 CTBUH Awards Program.
Download Zifeng Tower 2010 CTBUH Awards Book section

2010 CTBUH Awards Book

The CTBUH would like to thank Skidmore, Owings and Merrill for their assistance with this article.
Photography © SOM