The design concept for AHR’s 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. The building has been designed as LEED Silver and was completed in September 2013.
Brief 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.
Design concept Tower Form In order to generate the form of the towers, AHR 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, AHR 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 circular 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).
Dynamic Mashrabiya At the same time as the form of the towers was being developed, the team were keen to find a way of protecting the building from the extremely high levels of solar heat gain which could be expected. Drawing upon their knowledge of the region’s vernacular architecture the practice became intrigued by the use of “mashrabiya”. The “mashrabiya” is a popular form of wooden lattice screen found in Islamic architecture as a device for achieving privacy while reducing glare and solar gain. AHR has reinterpreted the concept of the mashrabiya at the Al Bahr 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 and dramatically reduces the amount of solar gain striking the façade. The dynamic screen avoids 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 and Development Working closely with colleagues at Arup, the team drew upon the skills of its in-house Research and Development 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.
Landmark By applying traditional design techniques in a contemporary manner, AHR has produced a distinctive solution which is entirely rooted in its culture and its environment. AHR has developed a solution for the new ADIC Headquarters 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.
