Recently, ArchDaily editors received an interesting request from an anonymous Communications Director of an unnamed New York firm, asking us “In your reporting, please do not repeat as fact, or as "official," the opinion that One World Trade Center in New York will be the tallest building in the United States.” He or she goes on to explain that the decision maker who 'announced' the building as the tallest in the US, the Council on Tall Buildings and Urban Habitat (CTBUH), is not officially endorsed by the AIA or the US Government, and that while their work is beneficial for architecture and cities as a whole, their criteria for height evaluation are flawed and have been criticized by many in the industry.
The desire to have the tallest building in a city, country or even the world goes back to at least the medieval period, when competing noble families of Italian hill towns such as San Gimignano would try to out-do each other's best construction efforts (jokes about the Freudian nature of such contests are, I imagine, not much younger). Perhaps the greatest symbol of this desire is the decorative crown of the Chrysler Building, which was developed in secret and enabled the building to briefly take the prize as the world's tallest, much to the surprise and ire of its competitors at the time.
With this competitive spirit apparently still very much alive, I thought it might be worthwhile to address the issue raised by our anonymous friend.
The decision by the CTBUH is a result of their primary judgment tool when it comes to measuring buildings, the “height to the architectural top,” which includes unoccupied spires, but disregards antennae, signage, flagpoles and other “functional-technical equipment.” This is admittedly not particularly scientific, as what constitutes a spire compared to a merely functional antenna is often subjective. 1WTC passes the spire test because of the way its plan tapers as it ascends; the spire, while admittedly puny in proportion to the rest of the building, is a continuation of this and can therefore be considered part of the building's architecture. In Chicago's Willis Tower the roof is in fact higher than the roof of 1WTC, but the design steps back asymmetrically instead of tapering. With the building's rectilinear form being clearly read from outside, the Willis Tower’s two antennae add little to the elegance of the overall design, and are therefore not included as part of the building's height. It is CTBUH's subjective decision to call the structure atop 1WTC a spire that makes it the taller of the two.
This type of “vanity height” has been the subject of much debate, and other methods of judging the height of a building have been proposed. The CTBUH acknowledges two alternatives, the “height to top floor” where the highest occupiable floor sets the benchmark, and “height to tip,” including all rooftop structures regardless of function or appearance. However, both of these methods also come with their disadvantages. 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.
Our anonymous contact also recommends a fourth method: the height to the roof above the highest occupied floor. This method may be instructive when comparing the flat-roofed Willis Tower and 1WTC, but it also has flaws when applied more widely: for example, the Shard has no roof at all above its top floor as the top few floors, including one of the observation levels, are open to the elements. 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.
So which of the four methods is best? I would argue that the methods of measuring the height to the top floor or the roof are fundamentally flawed, measures which, while objective, do not always relate to the experience of the building. It is worth remembering here that the acronym CTBUH stands for the Council on Tall Buildings and Urban Habitat, implying that their judgment criteria should indeed focus on the perceptions of the people in the surrounding area.
This leaves us with either the height to the tip, or to the architectural top. In his oft-quoted description of how to design tall buildings well, Louis Sullivan 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,” and 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?
The issue with the CTBUH's rankings lies not in the methods they use to measure height, but in their subjective decision to classify 1WTC's undersized lollipop stick as a spire. However I am more inclined to take issue with the building's developer and owners, and their decision to drastically cut back on the design of the spire in order to save money, in opposition to the designs – and explicit objections – from SOM's David Childs, the building's lead architect. Mayors and citizens of New York and Chicago can scrap over who has the tallest tower, but as experts in aesthetic judgment, these debates shouldn't much matter to us. Architects shouldn't be arguing over which building is taller, but rather which building is better.
So to answer the request: will reporters at ArchDaily refrain from calling 1WTC the United States' tallest building from now on? Maybe. Maybe not. But it doesn't matter.