The Tallest 20 in 2020: Entering the era of the megatall

CHICAGO – Within this decade we will likely witness not only the world’s first kilometer-tall building, but also the completion of a significant number of buildings over 600 meters (around 2,000 feet) – that’s twice the height of the Eiffel Tower. Two years ago, prior to the completion of the Burj Khalifa, this building type did not exist. And yet, by 2020, we can expect at least eight such buildings to exist internationally. The term “supertall” (which refers to a building over 300 meters) is thus no longer adequate to describe these buildings: we are entering the era of the “megatall.” This term is now officially being used by the Council to describe buildings over 600 meters in height, or double the height of a supertall.

As we started the 21st century, just 11 short years ago, the Petronas Towers held the title of “The World’s Tallest” at 452 meters (1,483 feet) in height. Taipei 101 took the title in 2004, at 508 meters (1,667 feet).Then, at the end of the decade, the Burj Khalifa set new standards at 828 meters (2,717 feet) – over half a mile high. Now, with work set to start on-site in January 2012 for Jeddah’s 1,000+ meter Kingdom Tower (see Figure 2), we can expect that in a mere two decades (2000–2020) the height of the “World’s Tallest Building” will have more than doubled.

Not only increasing in height, the “Tallest 20 in 2020” also demonstrate a diversity in project location not previously seen in the world’s tallest 20. The projects are scattered across 15 cities in 7 countries. China, with 10 of the 20 projects, clearly stands out as the country most rapidly pursuing the supertall, followed by Korea (3), Saudi Arabia (2), and the UAE (2). If we analyze via a larger geographic region, however, the picture becomes even more pronounced. Asia (not including the Middle East) accounts for 70% of the buildings (14). The Middle East counts for 25% (5). The only other region to be represented in the study is North America, where New York’s One World Trade Center is the only tower in the western hemisphere to make the study. If we consider the Middle East as part of continental Asia, then Asia contains 19 of the 20 projects.

The Tallest 20 in 2020 study ultimately underlines a now well-known fact: the skyscraper is here to stay. Shortly after 9/11, many predicted the death of the tall building, but as the study shows, skyscrapers are increasing in number, height, and diversity. The ever-increasing and rapidly urbanizing global population will continue to drive cities higher.

Not long ago, building height was primarily restricted by structural limitations. In the late 1800s, Chicago’s Monadnock Building demonstrated the maximum height achievable with a masonry structure while still providing an economically feasible space efficiency. Over the 19th century, many advances in the fields of structure, construction, and transportation (to name a few) allowed for a steady increase in building height. Now, the tremendous heights being achieved globally demonstrate that many of the physical constraints that once restricted height have been broken. The question for humanity is thus no longer “how high can we build?” but “how high should we build?” With every increase in height, there are energy implications in the construction, maintenance, and occupation of a building. Additionally, with added height comes less space efficiency, as structural members and service cores increase to service the increased height of the building. At what point are the significant benefits of increased density provided by building tall overtaken by the energy repercussions of height? This elusive figure is most certainly affected by the technologies of the day. Half a century ago, a megatall would have been considered possible only within a dream. It is now a reality. Is it not possible that we could soon see the emergence of a zero-energy megatall? Just as we pushed the structural boundaries of height, we must now continue to push the boundaries of environmental engineering in order to progress the tall typology. For, as skyscrapers continue to multiply, their effect on our cities – visually, urbanistically, and environmentally – continues to increase exponentially.