Council of Tall Buildings and Urban Habitat (CTBUH) which is considered the foremost authority on tall buildings has made it clear that it has four ways of measuring a building’s height. Out of the four, height to the architectural top is officially used to determine the list of world’s tallest building. Architectural top here includes unoccupied spires/pinnacles/parapets that are permanent and critical to the overall design while disregards antennae, signage, flagpole or other ‘functional technical equipment’.
This is the reason why the Petronas Twin Towers won over Sears Tower (now renamed Willis Tower) to become the tallest buildings in the world back in 1997. The twin towers reach the height of 452 metres including their architectural spires while Willis Tower goes up to 527 metres including its antennae. However, antenna is not included and hence the official height of Willis Tower is just 442 metres.
The other three methods on measuring a building’s height that can be seen as alternatives or extensions of the main measuring method are height to top of roof, height to highest occupied floor, and height to highest point (tip). The latter method is the one that counts everything from a building from its base to its very top including those ‘functional technical equipment’. Once Taipei 101 was built in 2003, the skyscraper cools down the controversy by topping the world’s tallest ranking in three out of the four methods. Then, Burj Khalifa came in 2009 to take all the top spots including the world’s tallest man-made structure and it is still holding the title now. The current list of world’s top ten tallest buildings is shown below which is measured in height to architectural top: (click on the image for larger version)
Besides than these four methods, other professional industries in this field of tall buildings such as the Emporis has its own set of methods too. But not to confuse anyone further, we will just stick to the more precise ones by CTBUH at this point.
There are still many parties who are not happy with these methods. They each has its flaws. The height to tip method rewards vanity height of all stripes, which could allow designers or developers seeking a height accolade to cheaply take the top spot using any poorly designed, extraneous addition to the roof. On the other hand, height to highest occupied floor does not acknowledge the impact that a building has on the experience of the urban environment – for example, the Burj Khalifa does not appear 584 meters tall but 828 meters, and as most of us will never be lucky enough to visit its topmost floor, it seems only sensible to judge its height based on its impact on the city’s appearance.
How about height to top of roof? In the variety of design of skyscraper nowadays, it’s very hard to judge the actual roof of a particular building. Is it just the roof over the highest occupied floor or roof covering the very highest portion of the building although the floor below it is not habitable. The Burj Khalifa has 244 meters of vanity height, but where exactly is the roof over its top floor? The tapered design of this building does not allow for such simple definitions. The definition provided also repeats the flaw of the “height to top floor” method, in that many skyscraper designs have significant architectural additions above this, which impact how they are perceived by those on the ground.
Hence, which of the four methods are the best? Of can you define what’s the ‘best’ or the ‘better’ here? Louis Sullivan, an architect who is always known as the father of skyscrapers, says “It must be every inch a proud and soaring thing, rising in sheer exultation that from bottom to top it is a unit without a single dissenting line”. If we take this to be true then it is clear that measuring the height to the tip, including – and rewarding – any and all of the clutter that often adorns the tops of skyscrapers is a move against design quality.
By contrast CTBUH’s official measurement tool, at the very least, holds designers accountable for ensuring that the way a building’s height is expressed is also a factor in establishing its quoted height. As architects, shouldn’t we support any tool which encourages tall buildings to be expressed elegantly? Recently, once the 1 World Trade Center in New York City is completed, another heated argument surfaces. Some claims that it is US tallest building but some said it’s Willis Tower. Many don’t see the antennae-like, awkward-designed and out-of-proportion spire on top of 1WTC as the key architectural element of the building. I too stand in that opinion. However, CTBUH has approved to have the spire as part of its architectural component in measuring its building height to the architectural top.
Increasing a building’s height with poor design is a big NO for me. Putting in a huge spire that is not proportionate to the overall building is a bad decision too. On the other hand, I do think it is necessary to have vanity height (non-usable height) to ‘complete’ a skyscraper especially when it is a tapering design on certain occasions. This issue actually leaves up a lot of questions and is open for multiple discussions.
Nevertheless, what’s important is that ‘the architects shouldn’t be arguing over which building is taller, but rather which building is better.’
(Images in this post are from the two sources listed above)