Al Bahar Towers – Abu Dhabi Investment Council Headquarters
Al Bahar Towers, the headquarters of the Abu Dhabi Investment Council designed by Aedas Architects, it has designed one of the first dynamic facades in the world. Based visually on the concept of a mashrabiya screen, this secondary facade has elements that open and close in response to the position and strength of the sun, to form a vital part of the solarshading strategy of the building.
The Al Bahar Towers in Abu Dhabi are not only remarkable due to their unusual facade – the twin towers also distinguish themselves through their innovative, sustainable design. The 145-meter-high towers were designed by the London-based architecture firm Aedas. One of the 25-story towers is home to the headquarters of the Abu Dhabi Investment Council (ADIC), which was also the building owner for this project. The head office of Al Hilal Bank is located in the second tower.
The greatest challenge for the architects was designing a sustainable building that is also compatible with the difficult climatic conditions. They achieved this by means of a cream-colored outer skin made of 2,099 translucent elements that cover the two towers like honeycombs and serve as a computer-controlled shading screen. These elements are mounted on the west, east and south side of the towers and automatically open and close as the sun moves over their surface. With its design, Aedas was inspired by the traditional Arabian latticework known as “mashrabiya”, which was mounted on the facade of houses to protect the private interior from public view. According to the architects, this dynamic solution has resulted in a reduction in energy consumption in the towers of around 50 percent compared with conventional buildings. Furthermore, photovoltaic cells are installed on the south-facing roofs of each tower, generating an additional five or so percent of the required energy.
“The new headquarters for Al Bahar Towers provides a modern symbol that is respectful of the culture and surrounding environment. Blending the latest technology with traditional design, our reinterpretation of the ‘mashrabiya’ used to reduce solar gain will be the first time such a moveable façade has been used on this scale. This, combined with the highest quality of materials, finishes and architectural features creates a distinguished and modern landmark for the Gulf region” – commented Aedas director, Bryan Hamilton.
“The Al Bahar Tower’s innovative dynamic façade opens and closes in response to the movement of the sun, reducing solar gain by more than 50 percent, creating a more comfortable internal environment for occupants and producing a distinctive external aesthetic which helps to define the building as a gateway to the UAE capital. The façade was conceived as a contemporary interpretation of the traditional Islamic “mashrabiya”: a popular form of wooden lattice screen found in vernacular Islamic architecture and used as a device for achieving privacy while reducing glare and solar gain.” – CTBUH Awards
Key Design Elements:
- Geometric Composition: The circle (2D) and sphere (3D) form the basis of most Islamic geometric patterns and 3D forms. The circle / sphere resembles unity, while the motion around a well defined centre resembles a uniqueness in identity and generates a unique axis. The intersection of the infinite arrangements and populations of the circles and sphere generate infinite arrangements of nodes. The ways with which these nodes are interpreted and linked generate the various relationships and forms.
- Main Form: Each of the tower floor plates is made of six tangential arcs, all of which are linked to the building profile to form an additional arc and includes a circular core in the middle. The form of the floor plates and tower profile provides a great deal of flexibility in terms of zoning and orientation.
- Main Structure: A unique crystalline/honeycombed structure has been derived from the underlying geometry which provides highly efficient load paths and creates a structural solution which is at once stable, flexible and economical. The structural form also embodies a high degree of redundancy which would be very resilient if damaged. The superstructure is expressed on the external face of the building reflecting the underlying geometrical framework. The unique honey-comb structure developed for ADIC is a world first.
- Internal Layout: The internal partitions generally radiate from the building core and meet the façade at the perimeter of the floor plates to provide optimal circulation and light distribution. A sky garden with a four-storey void above is provided at every 7th floor.
- Façade and Automated Shading Devices: A relatively clear glass curtainwall forms the “weathering” layer of the towers’ skin. A secondary veil comprises intelligent automated shading components that open and closes via centrally located linear actuators that react to the sun path. The shading veil acts as a dynamic ‘Mashrabiya’ (wooden lattice shading screen particular to the Middle East). The dynamic screen will reduce solar heat gain / glare and provide better visibility than dark tinted glazing which can distort the image of the surrounding view.
Standing in the desert of the Middle East, The Al Bahr Towers are a literal and figurative marker in the sand for a more considered approach to sustainability in the built environment. Time will be the ultimate judge, but it is conceivable that, years from now, their recent completion will be associated with the dawn of a new era in design in which inspiration will stem from the cultural and environmental criteria at the heart of sustainability. Featuring the world’s largest dynamic façade, The Al Bahr Towers proudly stand at the vanguard of this new tradition.
With a responsibility to sustain Abu Dhabi’s prosperity for the future, the client, The Abu Dhabi Investment Council had a mandate not only to assist the government in achieving continuous financial success and wealth protection, but also to actively support sustainable growth for the Abu Dhabi economy. The Council’s new headquarters represents a unique opportunity to create a landmark structure that embodies these ideals and reflects the standing and prominence of this new government agency.
The project brief required two 25-storey towers to create an outstanding landmark building that would provide a contemporary design using modern technology while considering the region’s architectural heritage together with the status of the clients’ organisation.
The aspirations of the brief were consistent with a number of other initiatives within Abu Dhabi at that time, namely the recent publication of the Abu Dhabi 2030 Plan, promotion of the Masdar initiative on renewable technology together with the recently published Estidama standard.
The design concept for Aedas’ innovative competition winning design is derived from an algorithmic composition, informed by Islamic principles of design, that has been supplemented by the application of a dynamic translucent ‘mashrabiya’ which opens and closes in response to the movement of the sun, reducing solar gain on the building facade by up to 50%. The resulting composition seeks to create a building which is both culturally and environmentally responsive, reflecting the aspirations of the brief while also respecting the emergent Abu Dhabi 2030 Plan.
In order to generate the form of the towers, Aedas applied the principles of geometric composition derived from traditional Islamic architecture. Geometric composition has been a defining characteristic of Islamic architecture for centuries, the circle and rotation reflecting the concept of unification and unity evident in nature; an important concept in Islam and in the emerging science of biomimicry.
Following an intense period of analysis, and influenced by both the client’s brief and also the orientation of the site, Aedas began to develop the distinctive form of the towers using parametric design techniques to generate a defining geometry. Their starting point was two cylindrical towers; a circle producing the most efficient form in terms of wall to floor area whilst also creating the greatest volume with the least surface area.
The radial plan form was articulated to reduce solar exposure on the most heavily exposed elevations and in so doing began to generate a natural orientation. The form of the towers was then sculpted around the core, narrower at the base and at the top, but broader around the intermediate floors. The crown of the tower was cut at an angle to maximise solar gain for roof mounted photovoltaics. Sky gardens were introduced in the most heavily exposed southerly elevation to further reduce solar gain while providing an amenity space for users.
Having established an underlying geometry, the team were then able to erode the elevation in order to generate the structural and cladding grids. The resulting honeycomb structure performs well in terms of its seismic response, (due to the number of vertical elements), well in terms of bracing (due to the number of diagonal elements), well in terms of redundancy (due to the number of alternate load paths) and well in terms of wind loading (by providing an aerodynamic profile).
At the same time the form of the towers was being developed, the team wanted to find a way of protecting the building from the extremely high levels of solar heat gain. Drawing upon its knowledge of the region’s vernacular architecture, Aedas saw an opportunity to integrate the very latest technological expertise with traditional design. The practice implemented a “mashrabiya”. Found in traditional Islamic architecture this popular form of wooden lattice screen is used as a device for achieving privacy while reducing glare and solar gain. Aedas has reinterpreted the concept of the mashrabiya for the towers by developing a series of translucent umbrella-like components which open and close in response to the movement of the sun. Each shading device is driven by a linear actuator to dramatically reduce the amount of solar gain striking the façade.
The dynamic screens avoid the need for heavily tinted glass thereby reducing the need for significant artificial lighting while providing better views for occupants of the building. This is the first time such a moveable façade has been used at this scale, enabling a reduction in solar gain of over 50%. The façade will be controlled via the Building Management System, creating an intelligent façade system.
Research & Development:
The team utilised the skills of its in-house R&D group to apply advanced computational design techniques in support of the project. The group developed bespoke applications to simulate the movement of the façade in response to the sun’s path and went on to support the detailed design development by undertaking a variety of simulations. The same advanced techniques were later used to derive the geometry from which a single integrated building model was created and this model was in turn used to ensure proper coordination of the various building elements.
By applying traditional design techniques in a contemporary manner, Aedas has produced a distinctive solution which is entirely rooted in the culture and environment.
Aedas has developed a solution in which form and function are combined into what could be called a ‘new vernacular’. The buildings will create a distinct gateway and a landmark on approach to the city.
Project name: Al Bahar Towers
Location: Abu Dhabi, United Arab Emirates
Coordinates: 24.456299, 54.401300
Type: Office Building, Skyscraper
Floor count: 27 + 2 basement levels
Floor area: 70,000 sq.m
Site area: 100,080 sq.m
Design Year: 2008
Construction Year: 2009-2012
Contract Value: £200 million
Completion Year: June, 2012
Client / Owner / Developer: Abu Dhabi Investment Council
Architects: Aedas Architects – G/F, 65 Chandos Place,, London WC2N 4HG, United Kingdom
Associate Architect: Diar Consult
Structural, Specialist, MEP Engineer: Arup
Cost Consultant: Davis Langdon
Façade & Mashrabiya Contractor: Yuanda
Landscape Architect: Townshend Landscape Architects
Main Contractor: Al-Futtaim Carillion
Sub-Contractor: Royal Mega Interiors / Al Shirawi
Project Manager: Mace International
Structural Steel Frame: William Hare
Text Description: © Courtesy of Aedas Architects, CTBUH Awards, sasint, geberit
Images: © Aedas Architects, Christian Richters, Beno Saradzic, Terri Meyer Boake, sasint