Broad Sustainable Building has built a number of their remarkable prefabricated towers in China, but none yet anywhere else. It's a shame, because they are extremely energy efficient, with their six inches of insulated walls and quadruple glazing. They are also extremely inexpensive, because of an absolute doctrinaire attitude to manufacturing efficiency and mass production using repetitive elements. They make Henry Ford look like a custom coach builder. The unrelenting focus on engineering has resulted in designs that can be most politely called utilitarian, (George Dvorsky at IO9 says "it looks like something a four-year-old designed with cereal boxes" ). That's a bit harsh; the latest renderings are a great improvement.
The building is an attempt to change the way we live and work; Architect Xian Min Zhang told TreeHugger Paula in an interview:
China cannot pursue the American or European lifestyle, it cannot afford it: work somewhere and live somewhere else, using cars and roads to connect.
Sky City will be a community of about 30,000 people, with offices, schools, restaurants and even a hospital. Instead of driving, people will get around in one of 104 elevators. It's not a luxury building, but an attempt to be "much more balanced in terms of mixture of people of different ages, professions and income levels."
When BSB first floated the idea of Sky City, a 220 storey tower, they were not taken seriously in North America or even in China, where I am told that people like to see validation by others outside the country. So they have decided to wow the world by building the J220 in their own backyard, in Changsha, home of Broad. It is a gutsy move, and many are not sure it can be done. Engineer Bart Leclercq, who worked on the Shard in London, has doubts and tells Construction Week Online that stiffness and wind loading is the real problem on a building that tall.
In order to get stiffness in your building you need lots of areas of concrete and steel. And in order to get that all in place, you need an enormous amount of time to bring it up, put it in place, put it all together, pour the concrete and put the reinforcement in place... For the concrete to harden, you can only take the shuttering away after several days. You can only pour a few metres height each time. So no, I do not think it is possible to build a 220-storey tower as quickly as the company claims. If they manage to build this structure in three months then I will give up structural engineering. I will hang my hat and retire. I will be eating humble pie as well.”
I suspect that Mr. Leclercq will be eating his humble pie in the not too distant future. Our contacts tell us that the building is going through some design modifications suggested by the design review panel in Beijing, and that "most likely breaking ground is any day soon."