China is home to 60 of the world’s 100 tallest buildings now under construction. But the skyward aspirations of Changsha, the capital of Hunan province, have inspired incredulity tinged with hostility.
Broad Group, a manufacturer based here in Changsha, has been planning to erect the world’s tallest building here this winter, and in record time. The 202-story “Sky City” is supposed to be assembled in only four months from factory-built modules of steel and concrete early next year on the city’s outskirts. The digging of foundations began on July 20.
Work nonetheless continued earlier this month at the site. Bulldozers sliced slabs of earth and six drilling rigs bored holes for a drainage system.
Mr. Zhang said in an interview at his headquarters that he had all the approvals needed to start work, and he and other executives said that it was common in China to keep working pending further approvals.
If built as planned, the building would be only 10 meters, or 33 feet, taller than the 2,722-foot Burj Khalifa in Dubai, the world’s tallest building since 2010. Sky City would cram 39 more floors into its height than the Burj Khalifa, partly because Sky City would be mostly apartments, which do not need the same hollow spaces under the floors as offices require for wiring and cooling, and partly because the ventilation shafts, electrical wiring and even indoor floor tiles will be packed into the modules while they are still at the factory.
The bottom 15 floors would include offices, a school with kindergarten through eighth grade and clinics. A schematic from Broad Group shows a hotel near the top and a restaurant and coffee shop at the apex.
The emphasis on apartments reflects the reviving real estate boom in China – some in China and abroad call it a bubble – as the government has told state-owned banks to lend more in recent months, in response to signs of weaker economic growth.
Mr. Zhang insisted that the local government in Changsha is not bankrolling his project. But he said for the first time in the interview at his headquarters on Aug. 7 that while Broad Group remains the official owner of the building, he has negotiated deals in recent months for the sale of practically the entire building to “four or five” investment companies. He said then that not all of these deals have been completed; on Tuesday, he declined to comment on whether the delay would affect his financing.
He declined to identify the buyers except to say that they were in the private sector, not part of the government and were spending their own money instead of relying on bank loans. That would be an extremely unusual combination in China, where most large real estate developments depend on low-rate loans that politically connected companies and individuals obtain from state-owned banks
Dennis Poon, the chief structural engineer for some of Asia’s tallest buildings and the vice chairman of the Thornton Tomasetti engineering firm in New York, said erecting a 202-story building out of prefabs was an extension of a global trend in the construction industry in the last few years. Many companies are using factories to make larger and larger pieces of buildings; Mr. Poon said an ambitious Chinese-owned hotel project that he was helping to build in the Bahamas used prefab bathrooms.
Relying entirely on modules means the 4,450 apartments will have little flexibility later to be turned into hotel rooms or offices if these should prove more profitable, he said. Assembling an entire building out of modules also considerably limits the flexibility of architects to create distinctive shapes that can symbolize a city
“Feasible? Yes, of course, but you get what you get,” he said.
David Scott, a recent chairman of the Council on Tall Buildings and Urban Habitat, a nonprofit group in Chicago, agreed that the project was feasible in engineering terms. China has much stricter standards than the United States for earthquake resistance, he said, and the lightweight, modular construction of Sky City will help it withstand quakes.
But while the exterior walls of the building will be very heavily insulated against the weather to save energy, the thin, lightweight floors may not block enough sound traveling up and down through the building.
“You will have a challenge of hearing the people above and below you,” said Mr. Scott, who is the chief structural engineer at the Laing O’Rourke engineering firm in London. “I don’t think it would meet market expectations here . “
International experts question whether Sky City can be built as fast as the Broad Group promises. Keith Brooks, the director of global property at EC Harris, a global consulting firm that is one of the project managers for the Kingdom Tower in Saudi Arabia, predicted that hoisting large modules high into the sky for a 202-story building would prove more time-consuming and difficult than Broad expects.
Large components tend to catch the wind like sails while they are being lifted by cranes. “I’m sure you can design the modules. The question is getting them up there,” Mr. Brooks said
Restaurant and coffee houses at the top
Hotel (171-202th floors)
Luxury apartments (121-170th floors) Ranging from 2,592 to 5,616 sq. Ft. in size
Top class apartments (61-120th floors) Ranging from 972 to 1,620 sq. Ft.
Medium-class apartments (31-60th floors) Ranging from 972 to 1,620 sq. Ft
Small apartments (16-30th floors) 648 sq. Ft.
Offices (6-15th floors)
Mixed Use (0-5th floors)
Basement (6 levels)
100 Story Yinchuan Tower
Broad Group is also building a 100 story Sino-arab friendship skyscraper in Yinchuan. The deals were signed
Grand Technology Group and Blue Mountains in Ningxia are building the Sino-Arab Friendship Building project, located in Jinfeng District, Yinchuan CBD center. It has a total area of 57.3 mu, building area of 300,000 square meters, a height of about 410 meters 100 layers built into a set of planning 5A class office, seven and five-star hotels, high-end commercial and apartments as one of the high-rise urban complex.
The Broad Group construction will
* use five times less energy versus conventional skyscrapers
* have 20 times cleaner air
* able to withstand category 9 earthquake
Traditional building materials generally use 1800 kilograms per square meter
Broad group buildings use an average of
* only 75 kilograms per square meter of steel
* 70 kg of concrete
* average weight per square meter to 300 kg
This is one sixth the conventional building construction material
Factory construction means only 1% of the waste of conventional construction.
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