You have just closed the door behind you and your dog is already jumping up your leg, demanding you take him for a walk. Normally this would mean a short journey in the lift or a few flights of the stairs. Not so if your apartment is in one of the world’s new super-tall buildings, where you might be hundreds of metres above ground. It’s no walk in the park to take a walk in the park.
You might think today’s skyscrapers are tall, but they are likely to be dwarfed by concepts and future designs pushing human construction higher and higher. In May this year, One World Trade Center was topped out and has become the world’s third-tallest building at 541m, restoring New York’s skyline and placing it back on the map of super tall buildings. The mantle of world’s tallest building is now held by Dubai’s Burj Khalifa, completed in 2010 and which reaches the lofty height of 829.8m. The presence of this enormous building and the fact that even more buildings of comparable heights were under way made the Council on Tall Buildings and Urban Habitat (CTBUH) introduce the – so far – latest category of high-rises: the mega-talls, buildings exceeding 600m in height. And this is likely to be just the beginning.
Obviously the quest for new heights is not at all new. What is different though is that the competition for tallness turned global and consequently fiercer and more extreme. Cities and regions compete against each other and require buildings as landmarks that create identity, symbolise power and riches and showcase sophistication way beyond their physical boundaries. At the moment the race to build skyscraping towers is about prestige; but one day they may help alleviate urban sprawl, allowing our megacities to curb their seemingly unstoppable spread.
The title of the world’s tallest building already has a new challenger; the Kingdom Tower in Jeddah, Saudi Arabia, which is intended to be the first to reach beyond the 1,000-metre mark. Originally, this project was aiming to introduce yet another category following the super tall: the mile-high building, but had to be scaled back because the soil would not take the weight.
Aside from the technical challenges, this category of buildings obviously also faces financial challenges. With investments easily going beyond $1bn, super-tall buildings aren’t usually intended to be economically viable as stand-alone buildings but are considered as part of a larger plan, where the signature tower adds value to a surrounding entourage of smaller, more efficient structures.
The challenges these super-tall buildings face are plentiful, requiring enormous financial resources, sophisticated engineering skills, a consolidated will amongst all parties involved to make it happen and finally people willing to work, live, use and pay for them on a daily basis. The sheer size of such projects calls for the right mix of functions that can be economically viable within such a structure, while the overall efficiency of the building suffers from a large core necessary to provide sufficient space for vertical transportation. Traditionally, the elevators needed to whisk us to the top of our towers require heavy cables to work properly; something which adds considerably to the building’s weight.
This summer, Finnish liftmaker Kone unveiled a new design – the Kone Ultrarope – which will shave some 60% off the weight of the elevator infrastructure, such as cables. Seeing as this has been one of the major factors standing in the way of ultra-high towers, plans that were once considered unfeasible because of weight issues may now see the light of day.