And the world's tallest building is…

At more than 2,600 feet high, the Burj Dubai (right) can still lay claim to the title of world's tallest building—although like all other super-tall buildings, its exact height will have to be recalculated now that the Council on Tall Buildings and Urban Habitat (CTBUH) announced a change to its height criteria.

CTBUH is the international body that arbitrates on tall building height and determines the title of “The World's Tallest Building.” The organization announced that its old rule of measuring height from the sidewalk outside the main entrance does not sufficiently recognize multiuse tall buildings that often have several different entrances at different levels. The new criteria calls for measuring building height from the level of the lowest significant, open-air pedestrian entrance.

“Beginning in 2007, with the knowledge that Burj Dubai would be significantly taller than any structure ever built, the CTBUH Height Committee met to review the criteria by which we recognize and rank the height of buildings,” said Peter Weismantle, chair of the CTBUH Height Committee and director of supertall building technology at Adrian Smith + Gordon Gill Architecture in Chicago. “As one might guess, with the committee being made up of architects, engineers, contractors, developers, building owners, and academics, a variety of opinions and views were expressed. The resulting revisions two years later reflect a general consensus of the committee in recognizing the most recent trends in tall building development around the world.”

In response to the changing designs and forms of tall buildings, the Height Committee also elected to discard its previous “Height to Roof” category. “The roof category just doesn't make sense anymore,” said CTBUH executive director Antony Wood. “In the era of the flat-topped modernist tower, a clearly defined roof could usually be identified, but in today's tall building world—which is increasingly adopting elaborate forms, spires, parapets, and other features at the top of the building—it is becoming difficult to determine a 'roof' at all, even less so to measure to it.”

The new rules haven't dramatically altered the ranking of the world's tallest buildings, although the Jin Mao Tower in Shanghai (1,381 feet high) dropped to seventh tallest, having been bumped by the Trump International Hotel & Tower in Chicago (1,389 feet high), which is now the world's sixth-tallest building.