In theory, we're in the midst of a "golden age" of skyscraper construction. But why, of the 10 tallest buildings on Earth, is nearly 30 per cent of each structure totally unusable spire? This week, the Council on Tall Buildings blew this scandal wide open with a report on the phenomenon, which it has christened "vanity spire".
In truth, this information is readily available to anyone with eyeballs. All supertalls (e.g. any building over 300m tall) have substantial spires and unoccupied upper floors, which serve to house hardware, observation decks and mass dampers that counteract the sway of the building in the wind. But even taking into account the necessary infrastructure, the majority of spires are totally unnecessary.
In fact, without the vanity height, 60 per cent of the world's supertalls wouldn't actually be supertalls at all. The Burj Khalifa would lose more than 213m. If an angry giant broke off the Burj's spire and planted it on the ground, it'd still be the 11th tallest building in Europe. The worst offender of all is the Burj Al Arab, of which 39 per cent is vanity spire (and, uh, vanity tennis court/helicopter landing paid). The UAE does lead the pack, but China and the US are nipping at its heels in the vanity department: New York City alone has three of the top 10 tallest spires in the world (the Bank of America tower, the New York Times tower, and One World Trade).
This is a relatively new phenomenon, one that has increased by roughly 400 per cent since the mid-1970s. There are plenty of socioeconomic ways to explain why it's increased: The title of world's tallest is traditionally a pissing match between international developers, and as the Skyscraper Index proposes, building height is tied to booms and busts. Spires, after all, are far cheaper than habitable spaces.
But there are technical reasons too. At a certain point, the amount of steel needed to stabilise higher floors becomes too large to validate. And the cost of building safely habitable spaces that high above the earth — where wind and temperature are extreme — is also hard to justify. Lifts are another issue: the logistics of installing enough lifts to service super-high floors, along with lifts in the expansive floor plates down below, is a major challenge.
So in a way, vanity spires are an act of desperation on the part of developers. Eager to carve out a little piece of history, but unable to justify the cost of building actual offices that high, they've turned to the next best thing: Slapping glorified communications towers on normal old skyscrapers. [Council on Tall Buildings via Dezeen]