Shanghai Tower: designing a bioclimatic transparent facade for China’s tallest building

Atrium glass wall

The atrium glass wall

30 January 2012 - With Gensler Architects, Aurecon has completed the design on the facade of what will be China’s tallest building.

At 632 m the Shanghai Centre will be more than 100 m taller than the recently completed Shanghai Financial Centre and is designed as a sustainable eco-tower that sets a new benchmark not only for the region but also the world.

The project is located in Lujiazui Financial Centre, beside the JinMao Tower and World Financial Tower, Shanghai, China. The project site is about 30 000 m2, with a floor area above ground of about 395 000 m2.

Aurecon’s facade engineers, with Gensler, developed the design to marry the facade with the structure and services systems while, at the same time, achieving architectural and sustainable goals. The twisted feature of the tower is an innovative upward spiralling design that reduces wind loads and captures rainwater which can be used for the building’s air conditioning and central heating.

The building is comprised of a circular central floor plate enveloped by a suspended outer skin triangular in plan, which twists as it ascends. The interstitial spaces between the form are used to create 12 storey atria that act as environmental buffer zones. These ‘sky gardens’ will provide a place to meet, eat and shop, cutting down the time people need to travel on elevators. Aurecon has also undertaken extensive building science and geometric analyses to help resolve the complex issues arising in design.

The challenge

Aurecon was asked to produce an integrated architectural, facade design that achieves low energy and low carbon in operation and include an integrated renewables strategy. The challenges included the changing geometries of the envelope which resulted in continually changing angular alignment and panel sizes.

Coordination between structure and facade components is essential in order to avoid construction issues relating to incompatible movement and tolerances between the structural frame and cladding elements, especially in tall buildings where methods of construction in service movements – due to creep, column shortening, wind and seismic effects – are an issue.

The building is very high and its shape is quite complicated, so wind tunnel testing and analysis was essential.

The facade of the building is developed as a suspended frame propped off of the tower structure. The frame is articulated to accommodate challenging geometry changes as the envelop twists in plan.

To accommodate significant thermal movements the connection details have been developed to accept up to 120 mm of vertical differential movement whilst achieving an architectural elegance. The combination of suspension and articulated framing achieves a marriage of technical solution and architectural expression.

Shanghai TowerExternal glass wall design

Due to the light weight nature of the steel frames, one of the main considerations was to prevent the lateral buckling of the steel beam in both major axis and minor axis. In major axis (lateral direction), preventing buckling was achieved by increasing the section depth in this direction by reducing the effective length through lateral struts or stainless cables; in minor axis, this is achieved mainly through the relatively closely spaced vertical cables.

The atrium glass wall is very large and complicated. Due to the twisting shape of the building, and the architectural facade design intent, the main steel structure will be primarily framed in a horizontal direction.

Aurecon studied a number structural options, some such as single cable structure or tension cable truss structures were excluded due to their large tension forces applied to the structure and the complex effects of the interaction of the base building and atrium structure. The final design included transparent glass mullions to provide additional stiffening to the glass panels.

Creating sky gardens

The building facade system uses double layer facade systems – the inner facade system functions on a circle plan with fully unitised curtain wall and the outer system on the twisted and tapered form. The sky atrium gardens act as a second wrapping around the main form. The height of the building is divided into 9 zones, each zone features a unique large glass atrium. The external glass wall is 58.5 m in vertical direction and the curved horizontal span is more than 60 m maximum. The atrium is created from the space between the inner concrete floor plate and the outer facade. The outer facade is a self- supporting free structure.

Sustainable design approaches

Sustainable green features have included the project development targeting the criteria set down by LEED-NC Rating System and Chinese 3 Star Green Building Rating and Certification System. These sustainable design features include:

  1. Tri-generation plant consisting of 2 sets of 1.1MW natural gas turbine; generating electricity, chilled water; hot water and heating water; simultaneous heat recovery of hot flue gas produced from the turbines thus reducing 49% carbon dioxide compared to the regular electrical cooling system.

  2. 15 nos. of 3kW vertical axis wind turbines (VAWTs) on the roof, providing 157,500 kWh of clean and renewable electricity annually.

  3. Greywater recycling systems located at basement and at mid-level, installed to collect greywater generated from lavatory or bathtub for reuse; reducing potable water demand for the office tower by about 40%.

  4. Ice storage system to shift part of the peak electricity demand of the chillers into the night mode/off peak operation, storage capacity is 26400 Refrigerant Ton (RT); reducing about 30% of the summit demand through this ice cooling storage system and saving up to about 3% of the yearly energy cost for the user.

  5. Large volume water deluge system with rotational nozzles installed at mid-level of atria delivering a large volume and accurate water spray onto fire with the assistance of Infra-red Detection to lock the exact location and very Early Warning Smoke Detection Apparatus System.

  6. Double curtain wall design provided better control on solar energy entering the tower building and resulting in energy saving.

  7. The spaces between the form are used to create the 12 storey atria that act as environmental buffer zones and maximised the opportunity of the double skins.

In addition to facade engineering design, Aurecon in conjunction with Cosentini Associates provided MEP (Mechanical, Electrical and Plumbing) design services including selection of the material, schematic design, development design, preparation of the tender documents and attendance of the specialist evaluation meeting.


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