Dubai:  Impenetrable secrecy surrounding the Burj Dubai's real height has confounded the American-based world body that officially recognises the world's tallest buildings.

Burj Dubai is reportedly 818 metres tall but the Council on Tall Buildings and Urban Habitat (CTBUH) says it has yet to receive any official notification from the builder Emaar of the record-breaking height.

Five years, three months and 15 days after construction started on September 21, 2004, the $4.1 billion (Dh15 billion) Burj Dubai is scheduled to officially open on January 4.

Dubai developer Emaar declined to elaborate on the structure or information about its opening, noting only that: "Details of the actual event will be revealed in due course."

However, in a previous interview with XPRESS, Emaar Chairman Mohammad Al Abbar did confirm the building is now "above 800 metres".

"It's a dream come true that I am associated with it," Al Abbar said. "It's a dream come true that it is opening in my hometown."

Click here for in-depth report on Burj Dubai

Jan Klerks, CTUBH Research and Communications Manager, said in an interview from the organisation's headquarters in Chicago that the whole world is waiting for Burj Dubai's opening day to learn the true height as declared by Emaar.

Official height

"We hope that the official height will be announced during the opening ceremony because at this moment, we don't know that yet. The number that has been floating around is 818 meters, but so far we have seen no official confirmation on that," said Klerks.

"I can see why the number wasn't disclosed during the development process as you want to make sure that by the time you open the building, it is not being surpassed by another project, but that argument doesn't hold any more."

 Continued reluctance

Emaar's continued reluctance to release the actual final height is frustrating, Klerks said.

"I don't know what causes the current secrecy other than making the press release of the opening more interesting. Now that the tower is completed, I think Emaar has more to gain by releasing the number, as people generally don't understand secrecy."

That said, Klerks said there is no doubt that Burj Dubai will lay claim to the tallest freestanding structure on the planet when it opens. "We include buildings in the lists of tallest buildings the moment they are officially completed. A good moment is the day when it's officially opened, so in this case on January 4 we should see a new number-one in our lists."

When the ribbon is cut by Dubai leaders, the $4.1 billion (Dh15 billion) centrepiece of the $20 billion (Dh73 billion) Business Bay development on Shaikh Zayed Road will knock the current record holder for tallest residential building - Taipei 101 tower in Taiwan - from the top spot, (CN Tower in Canada at 555 metres was the tallest structure prior to the Burj Dubai, but does not include offices or residences).

The Taipei 101 building has held the CTBUH record since April 14, 2004 and stands at 508 metres, which also accounts for the topped out spire.

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In a previous interview with Chicago architect Adrian Smith, XPRESS first reported that the Burj Dubai would top out with "160 habitable floors" for permanent, hotel and office occupants.

Meanwhile, Klerks said Burj Dubai is more than just another skyscraper - its opening represents a coming of age for Dubai and a new era for one of the more famous cities in the Middle East.

"Like no other building, the Burj Dubai embodies the development of Dubai in becoming a global city. It's being used as an image in articles about Dubai, and its opening will be a global news fact. In a way, the building is the biggest marketing campaign the city could have come up with. It really is the Empire State Building of the Middle East in many ways."

For the ultra rich, the new Dubai tower offers a truly unique address known around the world. "Put your name and that of the Burj Dubai on an envelope, and no postal service in the world will have problems delivering the mail," Klerks said.

Record holder

So how long will Burj Dubai hold on to the record as the world's tallest tower? Klerks estimates it will take at least "five years" for the next super tower to emerge.

The "1,001 metre tall Kingdom Tower project in Saudi Arabia seems to be the most serious contender for that title at the moment," Klerks said.

"But planning a next world- tallest and actually completing one can be quite a difference. We'll just have to wait and see what happens."

Reasons for secrecy

Emaar's reluctance to share facts is understandable given the fact that it is releasing a new book, Burj Dubai Opus which contains what the developer calls 70 per cent "exclusive content". The limited edition book which releases on January 4 includes "photographs, interviews and behind-the-scenes information in a giant tome of mesmerising cinematic quality," Emaar said. The book was done in partnership with Kraken Opus.

Burj Dubai opus

It is possible, surveyors told us, to measure the height of the steel-and-glass Burj Dubai structure within a few metres accuracy but no surveyor firm we spoke to would take on the task without permission from the building owners Emaar.

The developer is keeping the lid tight on the height until January 4, 2010.

One chief surveyor at a Sharjah firm told us that a theodolite, a traditional surveying telescope of sorts used to measure landscapes would work well to tell us how tall the structure is.

"It measures angles horizontally and vertically," he said, adding that to measure a structure like the Burj Dubai, a surveyor could use two nearby buildings and "triangulate" with the third building to get a known height. Another surveyor told us that aerial photographs of the Burj Dubai could be used to measure the shadows falling on the building and thereby come up with the height of the building.

Measured approach

Stronger lighter materials, innovative inventions and human ambition will continue to fuel the race to the top of the world by architects and developers around the globe, said Klerks.

"Tall buildings have always triggered the fascination of men for challenging the laws of nature, and the fun it is to overview the world from the inside, and I'm sure they will continue to do so in the future," Klerks said.

"On the technical development side, it's not one revolutionary finding that make taller buildings possible, it's a whole range of little inventions, efficiencies and improvements of materials, methods and management that make taller buildings feasible. And as always when you're going to do something new, you're going to bump into issues you didn't expect, because no one ever ran into them previously."