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Engineering Art and the Logic of Luxury

The challenges and opportunities of skyscraper cities

New York has shaped a new breed of skyscrapers – super slender and ultra-luxurious residential towers offering spectacular views of Manhattan.

432 Park Avenue, the highest residential building in the Western Hemisphere, 111 West 57th Street, the world’s most slender skyscraper, and the MoMA Tower, a building with no vertical facade lines, are just some of the examples of tall buildings being developed on tiny footprints.

Copyright dbox for CIM Group and Macklowe Properties

As Silvian Marcus, Director of Building Structures at WSP | Parsons Brinckerhoff in the USA, explained during his presentation on October 26 at the CTBUH 2015 Conference, engineers are going the extra mile to make these towers possible. They have a set of requirements that needs to be met while keeping the building safe, economically feasible and structurally sound. 

Their design must provide internal column-free spaces that increase usable floor area and offer views that are unobstructed by structural elements, as this is what high-end towers are all about. Using the highest strength concrete and outrigger systems that improve structural rigidity are among the methods to achieve these goals.

Despite not being a safety code requirement, providing high comfort levels for the occupants up in the sky is an absolute must for tall residential buildings. Controlling building dynamic movements is therefore one of the most important concerns for engineers. Using tuned mass dampers to control the building’s acceleration and creating open floors to minimize the influence of wind are some of the solutions that help stabilize the building.

Also, engineers need to provide efficient and elegant structural solutions to ensure that tower aesthetic is not compromised. As a result, according to Mr Marcus, the practice of structural design has become as much an art as a science.

But why are these towers so skinny?

According to Carol Willis, President of the Skyscraper Museum, views are valuable. Especially views of Central Park. So that is where most of the slender towers are popping up – around the south edge of the park.

But beyond the views, there is a strong international demand for New York’s real estate and a lack of land for new developments.

However there are also regulations. Floor to Area Ratio (FAR) sets the maximum floor space in square feet that can be developed on a given site. It doesn’t explicitly limit the height of towers but it limits the floor area instead.

If a building doesn’t use all of its FAR, the remaining development rights can be transferred to an adjacent building. And that’s how super slender towers get the right to soar in the sky: by combining the FAR portion of their minuscule footprint with that of the neighbouring lots or buildings. Carol Willis explained that, as long as a tower respects zoning rules and FAR, it can be built without public review process.

Courtesy of dbox and SHoP Architects

Floor plates are smaller which often means that there are one or two apartments on each floor. This strengthens the sense of exclusivity but also reduces the space needed for elevators, which again means more usable surface for occupants.

High ceilings reinforce the feeling of luxury and allow for more units to reach the sky, with less FAR, in order to access stunning views. Of course, lower floors have a purpose too. As they don’t offer stunning views they often include screening rooms, pools, gyms, spa and nanny apartments.

For Carol Willis, these towers are a real endemic species of New York. They emerged through specific constraints and opportunities of the city’s regulations following the economics of the logic of luxury.