The cities of Melbourne and Sydney are looking for inspiration from New York as they find themselves not only suffering from a glut of decent-sized CBD development sites but also overwhelmed by a high demand from blue-chip companies wanting entire skyscraper floors to themselves.
In fact, in both the Australian commercial and residential markets, the opportunity to buy a whole floor ‘in the air’ is extremely unusual.
But engineering methods and technologies that are tried and tested in the United States but that have been previously very rare in Australia are now enabling the challenges to be overcome and the demand of buyers and tenants to be met.
A building at 466 Collins St is the latest case in point. The structure is an impressive 298-metre high, 10-metre wide redevelopment of a historic Melbourne building by Golden Age and Asia Pacific Group.
In architecture, aspect ratios are used to measure the ratio of width to height. 466 Collins Street has a very high aspect ratio, making it the fourth-slimmest tower in the world.
“The narrow site required a rethinking of the structure of tall buildings,” said Kristen Whittle, director of the building’s architects, Bates Smart. “Through an inventive structural solution, combined with bespoke construction techniques, we have reinvented the tall tower. From a technical viewpoint it is testing limits of current construction systems capabilities available today.”
It is the more fundamental aspects of construction that pose the greatest challenge for narrow, tall buildings in the city. How can you build a tower quickly, cost-effectively and easily within the limitations of a closely built and heavily regulated urban environment?
“It is difficult to find efficient solutions that don’t cause delays to the overall time frame, which adds significant cost to the construction,” said Whittle. “To build successfully, the overall programming requires a rigorous and tailored approach to consider the timing of construction, sequencing of material and building techniques which provide the best solutions.”
A number of construction methods are viable in this case. One solution is to pre-fabricate large-scale elements off-site for onsite assembly, but it can be difficult to effectively plan the delivery, storage and assembly of such units on an extremely narrow site.
Another solution is to use a type of ‘slip-form’ concrete construction which sees all the construction occurring onsite. The challenges with this method come in effectively programming and maintaining continuity of the delivery of concrete and in ensuring the quality and tolerances are maintained with such a robust construction system.
High aspect ratios place even more pressure on a building’s stability. Melbourne’s climate, like that of New York, is conducive to significant wind and the subsequent pressure this puts on the tower. At 466 Collins Street, a liquid-tuned damper has been incorporated on the top of the building to solve this problem.
To ensure developments of this nature stack up financially, it is essential to maximise space and amenity. Bates Smart, in collaboration with engineers 4D, have come up devised a simple H-shape structure system at the heart of the building's structural system, which is made up of two long flanking walls braced centrally with two perpendicular bracing walls.
This has clearly defined the areas of usable floor space and has created a rational organisational principle that supports a very clear apartment planning regime.
The developer purchased the air rights over the adjacent building, which means the building was able to capture a significant amount of extra net saleable area through the use of cantilevered floors.
Whittle believes 466 Collins St is almost like a new class of building.
“The smaller floor plates give the building a club-like ambiance without the high volume hustle and bustle of typical large scale towers,” he explained. “The floor plates have clear, contiguous and connected on-floor views accompanied by super high levels of transparency and light penetration. The design also has big-building, blockbuster views down Collins Street and to the Yarra River, which are so sought after in the city.”
These blockbuster views are driving the continued addition of skinny skyscrapers to the New York skyline, as well as other major cities across the globe, to satisfy the demands of the uber-rich. The penthouse, for example, at 432 Park Avenue designed by Rafael Vinoly, where every one of the 104 apartments occupies an entire floor or half-floor, sold for $95 million.
New York has had a long tradition with skinny buildings dating back to the early 1900s. Here skyscrapers couldn’t be too bulky because a lack of good lighting and air-conditioning meant you couldn’t be too far from the window.
The first notable skinny skyscraper in New York was the Flatiron Building, which was made feasible by a change to New York City's building codes in 1892, which eliminated the requirement that masonry be used for fireproofing considerations. This opened the way for steel-skeleton construction. Once construction of the building began, it proceeded at a very fast pace. The steel was so meticulously pre-cut that the frame went up at the rate of a floor each week.
Now the thin building strategy has wider implications for cities. It means sites previously thought to be undevelopable now offer development opportunities. Old parts of the city can be revitalised, and historic buildings can be returned to their former glory while at the same time delivering the modern conveniences, comfort and style today’s market expects.
The design of these narrow skyscrapers, however, places a high level of demand on the architect, Whittle noted.
“The architect has to coordinate and distil the design through engineering and construction systems, and assembly requirements that are rare in today’s property industry,” he said. “This approach to design is reminiscent of the role of the architect during the development of the modern movement in architecture in the mid-20th century.”
“It is here where we see that there is a direct correlation between expression and construction,” he continued. “This brings a renewed level of authenticity to design in architecture that is refreshing to the industry as a whole and aligned with the renewed interest in construction and craft as seen in the world of industrial design.“
Cities need to be properly planned and protected during the course of population growth and densification, but they also need to be brought to life as welcoming, convivial and enduring, congenial places to work.
Ultimately, the designs of narrow skyscrapers like 466 Collins Street offer insights for the field of architecture engaged with the planning and development of our contemporary cities. They create an expansive design framework and reference point that is both technical as well as multilayered, highly engineered as well as aesthetically nuanced — aspects that have been woven together to create a highly contemporary outlook and design methodology.