Tall Buildings

Pleats Please

A folded curtain wall on an office building saves energy while throwing a few curves.

By Clifford A. Pearson

For much of the industrial age, factory roofs with sawtooth clerestories brought steady north daylight into spaces where workers toiled at assembly lines and production tables. For today’s office workers, the Bjarke Ingels Group (BIG) flipped this model on its side, wrapping the facades of the Shenzhen International Energy Mansion with a zigzagging curtain wall made of alternating panels of glass and powder-coated (PVDF) aluminum. Like its industrial predecessor, the 21^st-century wall system blocks a great deal of direct sunlight, reducing solar loads by 30 percent, according to the architects. BIG then took the concept one step further, pulling on the vertical folds in certain places, so they form supple curves that animate the elevations in surprising ways.

PHOTOGRAPHY: © LAURIAN GHINITOIU

PUSHING THE ENVELOPE
On the west facade of the 42-story tower, a bulging slit brings in extra daylight to conference rooms inside.

Located in Shenzhen’s central business district, not far from the Futian border crossing with Hong Kong, the 1 million-square-foot complex contains a pair of office towers and a nine-story connecting block with shared facilities such as a cafeteria, conference spaces, and retail. The top 13 floors of the 42-story north tower serve as the headquarters for the Shenzhen Energy Company; the rest of that building and all of the 19-story south tower will be leased to other tenants. While the Energy Mansion is surrounded by much taller buildings, including KPF’s 115-story Ping An International Finance Center, completed in 2017, it uses its curvaceous lines to stand out in the crowd.

PHOTOGRAPHY: © LAURIAN GHINITOIU

PUSHING THE ENVELOPE
The 19-story tower sits on the south end of the site.

BIG won the project in an invited competition in 2009 just as it was designing the Danish Pavilion at the 2010 World Expo in Shanghai. The theme for that Expo was “Better City, Better Life,” and the firm explored notions of “hedonistic sustainability” for its pavilion, says Bjarke Ingels, the firm’s founding partner. Many of those ideas, such as making green design beautiful and visually pleasurable, informed his work on the Energy Mansion too, as he tried to adapt modern architecture to the subtropical climate of Shenzhen. Updating the wisdom of vernacular design and collaborating with the firm Transsolar on sustainability issues, Ingels wondered if he and his team could develop “engineering without engines.” So they developed passive solar strategies such as using one tower to shade the other and designing a skin that would reduce solar loads and glare without expensive mechanical equipment. “As architects used to do, we put the performance of the building in its bones, not the machines added to it,” explains Ingels.

PHOTOGRAPHY: © CHAOS ZHANG (LEFT); LAURIAN GHINITOIU (RIGHT)

SCULPTED MASS
The architects sliced away some of the corners, eliminating the sawtooth facade there and introducing subtle curves to the rest of the building envelope (left). The two towers stand out without screaming for attention (right).

They ended up designing a curtain wall with tall, double-glazed panes of low-E tempered glass angled at 45 degrees in plan, so the clear portions face northwest on the west side of the building and northeast on the east side—always blocking out the stronger southeast and southwest sun with the rippled aluminum panels. Originally, the architects hoped to use solar-thermal panels that would power air-conditioning and dehumidification, but that proved too expensive.

After they established their design, the architects learned that Eero Saarinen had used a similar sawtooth curtain wall for his Laird Bell Law Quadrangle at the University of Chicago in 1959, a discovery that pleased them, says Ingels: “I’ve always admired Saarinen.” More recently, SOM designed a zigzagging glass envelope for its United States Courthouse in downtown Los Angeles (RECORD, March 2017).

The other ingenious aspect of the Energy Mansion is the way its folded facades get twisted into pleats at critical places—such as pedestrian entries at the northeast and southwest corners—and pulled out into a bulging slit on the upper portion of the west facade of the taller tower. These moves result in a graceful dynamism that becomes more apparent the closer you get. “We were inspired by the way Issey Miyake uses pleats in his clothes,” says Ingels.

PHOTOGRAPHY: © CHAOS ZHANG

MATERIAL MATTERS
For the public interiors, BIG used a palette of natural and industrial surfaces, including black stainless steel (bottom left), bamboo veneer (top), and white marble flooring (bottom right).

Visitors arriving by car enter the steel-frame building at the low connecting block between the two towers, where a three-story lobby features white marble floors and walls clad in anodized aluminum and black stainless steel. Bamboo veneer on the angled fins of the building’s sawtooth perimeter and a cascading sheet of water on one wall add touches of nature to the interior. On the energy company’s office floors, low cubicles occupy the areas in the middle, while casual tables and chairs fill in the spaces along the curtain wall. The company is still trying to figure out how to use the extra space on floors where the building bulges out. Currently these areas are furnished sparsely with random chairs, while adjacent meeting rooms face them to take advantage of daylight coming in from the vertical slit.

Due to a strict zoning envelope and a tight budget, “we focused our efforts on what we had the most control over—the facades,” says Ingels. These elevations, with their pleated wrapping, perform double duty—giving the project its distinctive identity and showing how sustainability can be sexy.

Clifford Pearson was an editor at Architectural Record for over 25 years. Now with the University of Southern California, he serves as a contributing editor at the magazine.

Credits

ARCHITECT: Bjarke Ingels Group (BIG) — Bjarke Ingels, Andreas Klok Pedersen, partners in charge; Martin Voelkle, project manager; Andre Schmidt, Song He, project leaders; Cat Huang, concept project leader

ASSOCIATE ARCHITECTS: SADI Shenzhen Architecture and Design Institute

INTERIOR DESIGNERS: BIG, SADI

ENGINEER: Arup

GENERAL CONTRACTOR: CSCEC

CLIENT: Shenzhen Energy Company

SIZE: 1 million square feet

CONSTRUTION COST: withheld

COMPLETION DATE: June 2018