Going up

With the average height of buildings in the region soaring, climbing stairs has never been more out of fashion.
Going up
By James Boley
Thu 11 Sep 2008 04:00 AM

With the average height of buildings in the region reaching more than 50 storeys, climbing stairs has never been more out of fashion. James Boley looks at designing in vertical transport.

In a region that's become accustomed to a certain level of pampering, it should come as no surprise that lifts or elevators-called ‘vertical transportation' (VT) throughout the industry-have become ubiquitous throughout the Gulf.

They're as essential a component to buildings as the front door, yet getting the design of a VT shaft wrong can have a dramatic effect on the building's functionality.

What if the guy in the penthouse suite at the top of the Burj Dubai wants to have a pizza delivered. - Kerry Galbraith, KEO.

Whether they're arriving to the office or returning home, people need to be able to move quickly through a tower. If they're unable to do so, continued congestion will warrant them finding another building in which to conduct their business-not exactly the building owner's desired effect.

Adding to this important challenge is the increasing popularity of the supertall tower, which makes VT even more critical. "What if the guy in the penthouse suite at the top of the Burj Dubai wants to have a pizza delivered?" asks Kerry Galbraith, head of the Structural Department for KEO International Consultants.

Though said in jest, Galbraith's concern shows how even the most mundane requirements demand a well-thought out VT system. So how do architects ensure that the penthouse owner gets a steaming hot Margherita or Meat Lovers with minimum fuss?

Start at the bottom

Facetiousness aside, the question of pizza delivery helps illustrate why a building needs to have a well-designed structural framework for a VT system. Getting the basics right needs to be done at the very early stages of design.

"The technical design-which is to do with specs of the elevator, i.e. the shaft dimensions-would happen early on in the design of the building," says Mamdouh Shehata, general manager of ThyssenKrupp.The reason for this is that the elevator shaft needs to be sized correctly according to the building's needs, lest its functionality be severely compromised.

Galbraith emphasises the importance of bringing in experts early on in the design stages. "Once we get into schematic and they start looking at systems within the building, at that point the VT consultant wants to be on board," he says.

"He can provide some basic guidance during the schematic stage as to the number and size of shafts and some layouts just to help the architect sketch out the core."

They shouldn't go on ahead and design the whole thing and then give the elevator manufacturer a fait accompli. - Yousef Shalabi, Otis.

The core, with its VT systems, mechanical and electrical rooms, and staircases, effectively acts as the spinal column of a building. A poorly functioning core-complete with logjams of people and insufficient space for facilities-leads to a poorly functioning building.

Compounding the problem is the fact that the core takes up valuable space that could otherwise be leased, which is critical for clients looking to maximise their ROI.

Yousef Shalabi, director of business development for Otis, illustrates how even a small reduction in core size can lead to big profits for a client. "Say you're saving 40-50 ft2 on the core per floor," he explains.

"Even at US $1000/ft2, that's $50,000 per floor. If you have 50 floors, that's $2.5m additional sale."

Top tips

With 2.5 million reasons for getting the right design, it's worth looking at how exactly architects can provide their clients with the very best arrangement for VT.One of the challenges facing designers is that although there are broad guidelines governing shaft sizes, each VT manufacturer offers cabs and cables that vary in size, meaning an architect has to consider this in his/her design.

The tendering process, whereby a VT manufacturer is brought in after the schematic design is prepared, means that an architect has to build in a certain level of flexibility.

"At the beginning of the design phase, we take estimates based on worst-case scenarios, so when you do go out to tender for the VT systems, you've got the right shaft size," says Galbraith.

Although you've gold-plated their sanitary fittings or whatever, what difference does it make if every time they comes to the lobby, they have to wait 10 minutes and then ride with 50 other people. - Yousef Shalabi, Otis.

The maximum speed of an elevator is set by its pit depth-the distance between the lowest finished floor and the bottom of the shaft-and its overhead-the corresponding distance between the ceiling of the top floor and the top of the shaft.

"If you set [pit depth and overhead] on your own, you're really limited in your choices on speeds and sizes," says Shalabi.

"The dimensions of everything should be set after they've finalised the VT design. They shouldn't go on ahead and design the whole thing and then give the elevator manufacturer a fait accompli."

Therefore, it is important to ensure experts are involved in the design process, especially since both engineers and VT supplier recognise that architects don't always have the necessary expertise. "Generally if you're dealing with international architects, they're very much on board," says Galbraith.

Not all practices, however, are as well equipped. "The market has filled up with a lot architects who are architects by name only," warns Shalabi. "Maybe 50% of buildings in Dubai are improperly designed."

Of course, a key point in elevator design is that passengers want to get to their destinations quickly-but not too quickly. "People only like to accelerate and decelerate so fast. When you go beyond those limits it becomes uncomfortable," warns Galbraith.Therefore, there's little benefit in over-designing pits and overheads.

Core control

Development in elevator technology means that, increasingly, the accepted guidelines for shaft and core design are being challenged. One of the main developments, according to Shalabi, is called ‘destination dispatching'.

Destination dispatching is where passengers pre-select their floor from a central computer system in the lobby; the technology then directs the passengers to the elevator that will take them to their desired floor the quickest.

"You press your floor number and the system says go to Lift A, it tells the next guy Lift B. It works out the best combination so that people using various lifts don't congregate in front of the first lift to arrive," explains Shalabi.

"With direct dispatching, combined with proper traffic analysis, architects can save intelligently, without really compromising the service to the building."

In addition to reducing overall travel time, destination dispatching also has an important impact in reducing the amount of space required for an elevator lobby. With passengers being more efficiently dispatched, lobby logjams can be avoided.

The higher floors of supertall buildings frequently lease for a premium amount, but of course, anyone in those higher floors will also demand a higher level of service. "You don't expect people who are paying $10m for the penthouse to have to wait 10 minutes for an elevator," points out Shalabi.

"Although you've gold-plated their sanitary fittings or whatever, what difference does it make if every time they come to the lobby, they have to wait 10 minutes and then ride with 50 other people?"

As much as new technologies can help free architects from design restrictions, design ideas from architects can also help allow the technology already present achieve its potential. Sky lobbies are particularly useful in supertall structures.Express elevators take passengers up to one of the higher floors, straight from the ground floor.

They then exit into the sky lobby and enter another elevator that will take them to their final destination.

"If you ran the elevators for all the floors all the way down to the ground floor, most of your floor space would be elevator shafts," says Galbraith. He recommends the use of sky lobbies buildings over 60 storeys.

Reaching the top

Given the technical issues surrounding VT, and the heavy penalties and compromises that occur when it is poorly designed, it's just plain business-savvy to bring in specialists to assist.

"The buildings we've had problems with are buildings, which the owner, for some reason, hasn't wanted to engage a VT consultant," says Galbraith "[In those cases] we're struggling from Day 1 to determine what needs to be where. It delays the whole design process."

Eliminating those delays is essential for design and functional excellence because, at the very least, neither the billionaire at the top of the Burj Dubai nor the average Joe/Jane at the top of their apartment block in Deira will have to wait quite as long for their pizza.

Big numbers

236 BCE:The year in which Archimedes built the first VT.

1880:The year in which Werner von Siemens invented the first electric VT.

60.6km/h:The top speed of Taipei 101's VT, the fastest in the world, located in Taipei, Taiwan.

85%:Number of buildings with VTs that do not have a named 13th floor, due to superstition that the number is unlucky.

4:The floor that is usually omitted in VTs in China, owing to the Chinese symbol for 'four' being pronounced the same as the symbol for 'death'.

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