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Sat 21 Apr 2007 02:27 PM

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Back to the future with prefab tower

Dubai's rotating 'prefab' skyscraper looks set to change the perception of the building technique.

The word ‘prefab' in the construction industry may bring with it the not-so-attractive connotations of flimsy, low-cost, post-war housing.

The stigma attached to these pre-assembled buildings as a quick and cheap, but not a particularly desirable or aesthetically pleasing form of construction, has been a difficult one to shake over the decades.

But a new project launched in Dubai earlier this month could change the industry's view of prefabricated buildings forever.

The US $330 million (AED1.2 billion) rotating tower is the brainchild of Italian architect and chairman of Rotating Tower Technology International, David Fisher, and is set to become the first prefabricated skyscraper in the world.

The concept poses several benefits to developers under time and cost pressures: with 90% of the 68-storey structure built as modules in a factory, actual construction time will be cut to 18 months, as opposed to the average 30 for a building of similar size.

Labour costs will also be reduced, as the project will only need around 90 workers on site, thus mitigating the risk of accidents and costs associated with health and safety.

And with 77 wind turbines fixed to the tower, along with solar panels, the project will run off natural energy, as well as produce enough to power five buildings in the vicinity.

The only part of the 313m-tall tower that will be built on site using traditional construction techniques is the central core, which will house lifts, emergency staircases and other utilities.

Each floor of the tower will consist of 12 modules that will arrive at the site completely finished, with electrical, plumbing and air conditioning systems ready to use. The modules will then be assembled at the rate of one floor every seven days.

The project will be made up of apartments, offices and a hotel, and will rotate 360° while changing shape. A single rotation will take 90 minutes.

Fisher is confident that prefabricated construction methods are the way of the future.

"I have never had any doubt in my mind that a building should be built in a factory," he said.

"It's very clear, so simple and so obvious. It's totally insane to do it any other way. In the future, nobody will build in the traditional way. They will follow this concept of pre-fabrication. There is no doubt about it."

Structural engineer Les Robertson, who worked on the former World Trade Centre in New York and is involved in the project, said the process is more economical and allows for better quality control.

"Prefabrication is absolutely the future of construction," he said. "It reduces the amount of labour required. It also takes away the risk of producing a building because it's made in a factory, and construction is a dangerous business - with this process, almost all the construction is done on the ground. It's faster to build, it's more economical and it's easier to control the quality of construction."

In a construction market that is suffering from skills shortages and pressures to complete projects in record time and within budget, the arguments for such a process are certainly compelling.

"In Dubai, you can have 2,000 people working on a construction site. It's difficult to coordinate them. You also have maybe 15 or 16 different languages being used," added Fisher.

"There are so many labourers working on each floor, they have to wait hours for the lift to bring them up. We will only need to have 90 people on site, as all the units are ready and just need to be hooked together. And in the workshop we only need about 700 people."

However, such a technique also demands skilled labourers.

"Finding skilled labour is one of our main challenges. Most of the ‘know-how' will come from countries such as Italy, Germany, Holland and the UK. They will then train workers from other countries."

The cost of the project will also be far more tightly controlled, according to Fisher.

"Developers here ask me two questions: how much will it cost? And how can you guarantee the price? In an industrial facility, the contingency will never be more than 3%. Any industrial product will never have more added cost because there is a production line."

A 30,000m2 facility is currently under construction in Jebel Ali, which should be operational in the next five or six months. From here, units will be built first for the tower in Dubai. The factory will then serve as a base for the construction of units to serve similar prefabricated towers in cities around the world. After Dubai, the company has plans to build similar projects in 11 other major cities including Moscow, New York and Tokyo.

Fisher has assembled a team of international consultants that will be involved in carrying out the rotating tower project on a global scale, including project manager Bovis Lendlease, plumbing specialist Viega, construction chemicals company, Kerakoll, transport consultant Barker Mohandas, construction manager Kriston and mechanical engineer IV Industrie.

The company is also negotiating a contract worth around $82 million with local joint venture Besix for the on-site foundations and construction work.

"Besix is not included as part of the ‘club', because on each site and in each city we will select another contractor. The contractor has a very minimal role; just the foundation and the core."

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