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. 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 have 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.