The Council on Tall Buildings and Urban Habitat was founded by Lynn S. Beedle in 1969 at Lehigh University in Bethlehem, Pennsylvania.
Prior to 1976, the CTBUH was known as the “Joint Committee on Tall Buildings,” a joint group originally formed by the International Association of Bridge and Structural Engineers and the American Society of Civil Engineers in 1969.
In 2003 the Council moved from Pennsylvania to the Illinois Institute of Technology (IIT) in Chicago, USA. The next 13 years saw tremendous growth for the Council, with a Research & Academic office opening at the Iuav University of Venice, Italy in 2014 and an Asia Headquarters office opening at Tongji University, Shanghai in 2015.
Having outgrown the space available at its IIT headquarters, in 2016 the Council expanded into the historic Monroe Building in downtown Chicago and established a Research & Academic office in the space remaining at IIT campus.
CTBUH – A Historical Sketch
[Reprint of: BEEDLE, L.S. (1992) CTBUH: A Historical Sketch. Structural Engineering International, p.160]
By CTBUH Founder, Lynn S. Beedle
It all started with the IABSE. It is not often that one can remember the precise start of something… right back to the moment he had the idea. But in the case of the Council on Tall Buildings and Urban Habitat, I can: The afternoon of Friday, September 13th 1968 at the 8th Congress of the IABSE in New York. Prof. H. Beer of Austria was summarizing the theme, “Tall Steel Buildings”, and I was struck by the significant tall building research he was describing. This research was not being coordinated or evaluated in a form useful to the designer. It spoke of the need for an international effort to bring information together.
Acting upon that idea, I wrote to Prof. Beer and in due course he responded that international exchange indeed should be started. By that time, it was February, 1969 and at a meeting of the US
Group of IABSE in New Orleans, then chairman Elmer Timby, asked us to suggest a topic that we could “gather around” as a basis for more frequent exchanges with our professional colleagues overseas. Here was the opportunity to implant the idea: the preparation and updating of a Monograph that would provide a focus for continuing exchange. It would be a joint activity between the IABSE and ASCE – hence its original name “Joint Committee on Tall Buildings”.
Jewell Garrlets made the presentation to IABSE at its following meeting in Britain in September of 1969. Approval by the American Society of Civil Engineers came shortly afterwards. National Science Foundation funding was approved and we were on our way. The Headquarters was established at Lehigh University, Bethlehem, PA, USA.
The need for the Joint Committee was more than just the desire to get together. It stemmed from things like the exploding urban population, creating an increased demand for tall buildings; the need for economy in construction; the frequent neglect of human factors at the expense of livability and the quality of life; the need for new research required in the field; and the necessity of establishing priorities for such reasons.
The timing was right, too. There were very few high-rise buildings built in the 1950s. But by the 1970s, tall building construction increased substantially.
As a result of the increased emphasis on planning and environmental criteria in 1973, the American Institute of Architects, the American Planning Association, the International Federation for Housing and Planning, and the International Union of Architects were invited to join the forming organizations as equal participants with IABSE and ASCE. The American Society of Interior Designers, the Japan Structural Consultants Association and the Urban Land Institute also later became sponsoring societies. Then, in 1976, the “Joint Committee” changed its name and became known as the “Council on Tall Buildings and Urban Habitat”. In 1979 it was admitted as a Category B non-governmental organization of UNESCO.
One of the well-remembered Steering Group meetings was one of the first, at which Les Robertson and the late Fazlur Khan were debating the question of “What is a tall building?” After all, if we were going to do a Monograph on tall buildings, one needed a definition. The final decision: A tall building is not defined by its height or number of stories. Rather, the important criterion is whether or not the design is influenced by some aspect of “tallness”. It is a building whose height creates different conditions than those that exist in common buildings of a certain region or period.
The Steering Group next organized the 1971 conference in Bled, Yugoslavia, to bring together specialists from all over the world to decide what this Monograph would be all about. Delegates reviewed the abstracts of papers that later would be presented at the First International Conference (they are now called World Congresses) held at Lehigh University. More than 700 people attended this later five-day event from August 21 through 26, 1972. Adhering to a strictly enforced 7-minute time limit, 261 “reporters” and over 200 discussers participated, coming from 30 countries. Twenty-seven preprint volumes were available to the participants, followed by a five-volume set of Proceedings. It is still known around the world by Council members as the “Lehigh Conference”.
That conference was followed by an intensive series of follow-up conferences—20 being held in the 1972–1975 period. Their essential function was to disseminate the information coming out of the Lehigh Conference and to collect material for the Monographs.
Throughout it’s history, the Council has continued to strive toward the dissemination of information and the stimulation of research on tall buildings throughout the world. It continues to have a major concern with the role of tall buildings in the urban environment and their impact. It is not an advocate for tall buildings per se; but in those situations in which they are viable, it seeks to encourage the use of the latest knowledge in their implementation. In addition to sponsoring conferences on a regional and international basis, the Council has continued the work of the original Monograph, publishing updated volumes, a regular newsletter, and other reports and support documents.
Much has been accomplished by the Council, but most important perhaps, are the relationships that have been established with colleagues from a wide range of professions and from all over the world. We thank Prof. Beer for lighting the spark on September 13, 1968. And we thank Elmer Timby for asking the right question.
The CTBUH is the recognized arbiter on tall building height, and the body that determines the title of “The World’s (or Country’s or City’s) Tallest Building”.
It maintains three definitions for measuring tall building height along with numerous definitions pertaining to tall building height, function, materiality, etc. Its official Height Committee was formed in 1993, but the function of determining height, data and “tallest” titles pre-dates this, with the creation of the first official “CTBUH 100 Tallest Buildings in the World” list first appearing in the 80’s and which is now published in numerous reference books and periodicals each year.
Of course skyscrapers had been in existence for almost 80 years before the Joint Committee on Tall Buildings (as the Council was first known) formed in 1969. The first skyscraper (acknowledged because of its use of a curtain wall construction on a steel frame) is generally accepted as the 1885 Home Insurance Building by architect William Le Baron Jenney in Chicago. Being the first skyscraper, it was also the first to claim the title of “World’s Tallest Building” at 55m (180ft). Next to claim the title was the World Building in New York in 1890, followed by the Manhattan Life Insurance Building in New York in 1894. Most of the early skyscraper designs had flat roofs or domes at the top of their structures and were measured from curb to the top of building, with flagpoles generally not included. So, there wasn’t too much to debate when it came to claiming the “World’s Tallest” title. Even in 1905 when the New York Times Building, New York, was completed at 111m (363ft) to the roof with 128m (420ft) including flagpole, it was not considered to be taller than the 119m (391ft) high Park Row Building (also located in New York), which had held the world’s tallest title since 1899.
Following the Park Row Building, the Singer Building in New York was next to claim the title of “World’s Tallest” in 1908. It was surpassed the next year by the Metropolitan Life Insurance Company Tower in New York in 1909. In 1913 the Woolworth Building was completed and would claim the title for the next 17 years.
Things got interesting in 1929, when two buildings in New York competed neck and neck to surpass the Woolworth—the Bank of Manhattan and the Chrysler Building. The Bank of Manhattan topped out at 282.5m (927ft) while the Chrysler Building’s final height was planned at 281.9m (925ft). But just a few months after the Bank of Manhattan was completed, a spire was secretly assembled in the Chrysler Building’s dome and hoisted into place, bringing the total height to 319m (1,046ft). The spire was considered an architectural element of the building, thus giving it the world’s tallest title over the Bank of Manhattan. The Chrysler Building only held the world’s tallest title for just less than a year however, when the Empire State Building was topped out at 381m (1250ft).
After the Depression and World War II, most new skyscrapers used the “International Style”, which typically had an orthogonal form with flat roofs and no spires. Many of the new buildings did add radio and television antennas to their tops, but these were not included in the official heights of the buildings.
The Empire State Building held the world’s tallest title for 41 years until New York’s 1 World Trade Center took over at 417m (1,368ft) in 1972. But its title was short-lived when Chicago’s Sears Tower was completed in 1974 at 442m (1,451ft). There was some debate at the time that the 540m (1,772ft) Ostankino Tower in Moscow (1967) and the 553m (1,815ft) CN Tower in Toronto (1976) should be considered the world’s tallest building, but since they were basically communication towers with observation platforms and not buildings in a traditional sense, the CTBUH did not consider them contenders for the “World’s Tallest Building” title. Instead each was designated as “the world’s tallest self-supporting tower.”
Defining the Criteria
So what actually is the world’s tallest building in terms of the criteria? The answer to this question is perhaps not as simple as it might first appear. First of all, the issue of what constitutes a “building” needs to be addressed, and how is it measured? Early discussions between CTBUH founders such as Lynn Beedle, Fazlur Kahn and Leslie Robertson in the early 70’s after the completion of the Sears Tower in Chicago came up with some basic height criteria. Here are a couple of excerpts taken from the later 1986 CTBUH publication “Tall Buildings of the World,” based on these early discussions:
A “building” is considered to be a structure that is designed for residential, business or manufacturing purposes. An essential characteristic of a building is that it has floors. Height is measured from the sidewalk of the main entrance to the structural top of the building including penthouse and tower. Television towers, radio antennas and flagpoles are not included. On the other hand, a tower is included if it is enclosed as an integral part of the structure—the Chrysler Building, for example. The number of stories begins at street level, main entrance.
The incident that really brought the whole issue of height—and the Council on Tall Buildings and Urban Habitat’s Height Committee—to prominence, was the debate in 1996 between Petronas Towers Malaysia and the Sears Tower Chicago. With their decorative spires considered part of the architectural height (similar to the Chrysler Building some 70 years previously), the 452m (1,483ft) Petronas Towers took the title of the world’s tallest building away from the then holder Sears Tower by 9.7m (32ft) since the antennae of Sears at 519m (1,704ft) height were not included in its height measurement.
However, the twin Petronas Towers were only 379m (1,242ft) without the spires, which was much shorter than both the highest inhabitable floor and the roof of Sears. Thus viewing the Petronas and Sears Towers side by side (or seeing them in diagrammatic form), it seemed that Sears Tower was much taller, since the two 77m (253 ft) TV antennas brought the total height to 519m (1704ft). At the April 1996 CTBUH Height Committee Meeting, it was decided that the spires should count in the official height of the Petronas Towers, thus giving it the world’s tallest title, but it was a decision that many (especially Chicagoans!) disagreed with.
Partly in response to this situation, the Council created a further three new height categories: highest occupied floor, highest roof and highest tip of antenna, but this did not necessarily settle the issue, since the architectural height (including spires but not antennae) was the one that determined the world’s tallest title. This decision on Petronas versus Sears brought international attention in the news media since this was the first time a country outside the United States had held the world’s tallest building.
The Sears Tower still held the titles of highest floor (436m/1,431ft) and highest roof (442m/1,451ft), while 1 World Trade Center, New York held the highest antenna title at the time at (527m/1,728ft).
Things transitioned again in 2004 with the completion of Taipei 101, Taiwan, which became the world’s tallest building at 509m (1,670 ft), beating the Petronas Towers by 57m (187ft). A meeting of the CTBUH Height Committee convened in March that year recognized Taipei 101 with the world’s tallest title, along with the highest occupied floor (438m/1,440ft) and highest roof (448m/1,473 ft). There was still some disgruntlement from the US though, as the Sears Tower antennae were still higher than the spires of both Petronas and Taipei 101, at (527m/1730ft—the western antenna had been extended in June 2000 by 8m/26ft). Sears had achieved the title of the “tallest to tip” through default in 2001, after the terrorist acts of 9/11 and the destruction of the World Trade Center towers, New York.
On 24th May 2007 the CTBUH held a Height Committee meeting at the Illinois Institute of Technology in Chicago with an international attendance to debate further the robustness of the existing height criteria, especially in light of projects such as the New York Times Building, New York, which was due for completion soon after with an architectural spire which looked to all intents and purposes like an antennae (and in light of several other projects which had architectural spires which contained antennae). The complexity and emotive subjectivity of the issues were apparent however in that, after a full day of involved debate, no change to the criteria was agreed on. The following points found a majority preference at the meeting:
On September 15, 2009 a sub-group of the CTBUH Height Committee held a meeting in Chicago, specifically to discuss the shortcomings of the existing criteria in response to the ground conditions at both Trump International Hotel & Tower, Chicago and the Burj Dubai. All four CTBUH height categories were currently worded: “Height is measured from the sidewalk level outside the main entrance to…” but this is problematic as the world of tall buildings is increasingly witnessing (as in the case of both Burj Dubai and Trump), multiple significant pedestrian entrances at differing levels.
As a result of that meeting, the full height committee passed the changes in wording to: “Height is measured from the level of the lowest, open-air, pedestrian entrance to…”. The height committee felt this offers the protection from buildings including sub-grade basements, car parking, etc. in their height figure, while allowing buildings such as the Burj Dubai to be not penalized for having a lower but above-grade entrance which may not be considered “main” but allows people to enter and exit the building at that point nonetheless.
This change resulted in the Burj Dubai being measured from the office entrance, which is the lowest of 3 entrances (residential, hotel, office), and also resulted in Trump Tower being measured from the public riverwalk, from which residents can enter directly into the building, and the public can enter the retail elements which are contained within the tower footprint. Interestingly, it also moved the Trump Tower one up the tallest rankings at 423m (1,389ft), from 7th to 6th place at the time of its completion, leap-frogging Jin Mao Tower at 421m (1,381ft). Also in response to the changing designs and forms of tall buildings, the Height Committee has elected to discard its previous “Height to Roof” category.
The CTBUH Height Committee continues to meet regularly to review and, occasionally, refine the existing height criteria.
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