You’re so vain, Burj Khalifa, you probably think this post is about you. The 2,716-foot-tall tower recently topped the list of the world’s vainest skyscrapers. The peculiar distinction comes from a just-released study by the Council of Tall Buildings and Urban Habitat (CTBUH) that measures the unusable space of these structures.
The CTBUH’s report tabulates the "vanity heights" from a pool of towering buildings that includes the Burj, the Burj Al Arab, the Zifeng Tower, and the New York Times Building, among others. The dimensions measure the distance from the uppermost occupied floor to the structure’s peak; from these, the CTBUH generated a percentage of each building that is unoccupied, which, you may have noticed, often comes in the form of a gestural but virtually unusable spire. On average, said spires account for nearly 30% of the height of the skyscraper cases.
The results are depicted in the visualization by superimposing the percentages onto elevations of each tower. The method is misleading, however, and pits the data against one’s visual intuition. You have to double check the numbers when, say, the Bank of America Tower’s "vanity ratio" exceeds that of the much taller Burj Khalifa. Seen side by side, the latter clearly looms over the former and hemorrhages far more unused height (800 feet of it). But proportionally, the BoA tower is the greater offender.
More interesting, the report posits that more than half of the so-called supertalls—any building over 1,000 feet—would lose their status if their spires were removed. According to the index, 44 of the world’s 72 tallest buildings would revert to just "aspiringly tall" towers, the kind that dot the downtowns of midsized American cities. In the Burj’s case, if its vanity height were severed from the building’s occupied floors, it would still be the 11th-tallest skyscraper in Europe. The UAE, in fact, lays claim to five of the 10 structures on the list, with the Burj Al-Arab with the greatest "vanity ratio," that is, the largest vanity height proportional to its overall dimensions.
Of course, it’s important to point out that unoccupied space doesn’t necessarily equate to wasted space. In every tower, the top floors are filled with machinery, systems hardware, and structural safeguards (e.g., mass dampers), all things that are integral to a structure’s performance. But it should be clear that these buildings bend toward frivolous excess.
The study, however, is indicative of the architectural ambitions of our time. Skyscrapers appear with astonishing speed in emerging cities in every shape imaginable. As advanced rapid fabrication and engineering models advance, the form of the skyscraper will continue to change dramatically. In short, expect a lot more vanity to come.
[Image: Burj Khalifa, Sophie James via Shutterstock]