Chinese construction company Broad Group has announced ambitious plans to construct the world's tallest skyscraper in an implausibly swift 90 days. If the target is met, the 838-meter (2,750-ft) "Sky City One" will take only a twentieth of the time that the Burj Khalifa, the world's current tallest building, took to construct, and will stand 10 meters (33 feet) taller still upon completion. The secret to the rapid construction is prefabrication. Approximately 95 percent of the building will have been put together in modular form before work even commences on site.

Broad has form in the area of rapid prefab construction. The company, which primarily makes air conditioning, has already demonstrated its Broad Sustainable Building (BSB) concept, albeit at a much smaller scale. It built the 15-story New Ark Hotel prototype in one week and a 6-story demo pavilion in a single day. Broad is clearly confident that the SBS principle can be applied to the 220-story Sky City One, perhaps taking confidence from a 30-story prototype withstanding a simulated "magnitude 9 earthquake."

Broad has described Sky City One is a self-contained earthquake-resistant carless city which will not only accommodate approximately 100,000 people, but provide them with retail and leisure facilities too.

According to CNN the Sky City One will contain 1,000,000 sq m (10,800,000 sq ft) of usable floor space and its 220 floors will be connected by 104 separate elevators. Broad CEO Zhang Yue reportedly claims that the tower will consume only one fifth of the energy of a conventional building of its size (if you can call any building this tall conventional) due to sustainable design approaches built into the BSB concept including 15-cm (6-inch) thick exterior walls and quadruple glazing, both of which up Sky City's insulation.

CNN reports that the the Sky City One is projected to cost US$628 million: positively cheap when compared to the $1.5 billion Burj Khalifa. Work is due to commence on site in November 2012 with completion due the following January, though final approval from Chinese authorities is yet to be granted.

Sources: CNN, Broad Group