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January 2019

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Luma Bendini

Can a single building change the wind microclimate of an entire area?

Let’s exercise ‘wind-intelligence’ by placing 3 famous buildings inside Central Park and analyse wind behaviour around different building shapes. Because CFD is fun!

The effort to make wind-comfortable urban environments is one of the main challenges urban planners face nowadays. Cities are denser, and buildings are taller. Structures are inducing faster winds from higher altitudes to ground level and significantly affecting peoples’ perceived outdoor thermal comfort.

The neighbourhood area that will surround a new building today might be significantly different in 5 to 10 years. Can wind studies evolve as fast as cities so that constructors are able to build long-term sustainable and comfortable urban spaces?

How a building's shape affects wind perception in an area of interest

Back in the year 2000 while designing the Park Hyatt Towers, a 257 metre skyscraper in Chicago, wind tunnel testing showed that the tower would be under significant effects of wake buffeting. It was provoked by northerly winds passing through the existing John Hancock Tower, a 343 metre-high-structure nearby.

As acceleration was way above desirable levels, an extensive examination was performed after the first wind analysis. This resulted in changing the structure and its shape to decrease acceleration: a 300 ton tuned mass damper was added to the project.

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Wind tunnel testing showed that Park Hyatt Towers would be under significant effects of wake buffeting, provoked by northerly winds passing through the existing John Hancock Tower.

With increasingly dense cityscapes, taking into account the surrounding areas of an urban development is a must! Especially when considering the wind (and also light for that matter, but we are mainly focusing on airflow here).

This is important to provide insights on major and minor aerodynamic modifications in order to either adapt a big structural system from very early design stages, as the mentioned Chicago example, or to evaluate the need for canopies and other wind mitigation structures during later design stages.

So, is a single building capable of changing the wind microclimate in an entire area?

The inputs for this experiment are:

  • 1 of the world’s most famous neighbourhoods: lower Central Park area, New York City.
  • 3 award-winning architectural projects: Flame Towers, Guangzhou Opera and The Gherkin.
  • Wind Simulations by Ingrid Cloud: one wind direction, same inflow velocity and visualisations focused on pedestrian level (2 metres high).

Flame Towers, Azerbaijan
Opening: 2013
Height: 182m

The streets in New York City are aligned in parallel, and in this case even parallel to the inflow direction. Thus, without an object standing in the way upstream, the wind would be split proportionally between these streets. However, the flow separation by the Flame Towers is causing the wind to accelerate in certain streets. If those streets are shopping areas or an important public transport location, it would require a closer examination to evaluate safety implications.

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Guangzhou Opera, China

Opening: 2010
Height: 120 m

The freestanding concrete auditorium has a very irregular shape. Maximum height is 120 metres, while the overall structure is about 43 metres high (it’s a medium rise building). As it can be seen in the following two images, the wind is not significantly altered by adding this building. The wind dynamics around the highest nearby building is mostly affected by the imminent structure located around its front.

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St Mary Axe (The Gherkin), London

Opening: 2003
Height: 180 m

This is a very aerodynamic-friendly shape because the overall cylindrical geometry allows for the wind to move around the building without being forced downwards. Curiously enough, the round shape creates a vortex (fluid flowing around a common axis) directing the wind to the rooftop of the neighbouring building in the back. A rooftop open area would be struggling with this oscillating motion of the wind coming from the Gherkin.

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Read more: 

Old vs New: wind effects around 6 iconic buildings

Automated adaptive mesh optimisation/refinement

Ingrid Cloud Demo