Desert-smart towers carry their own sunscreen

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By Nick Leech  www.thenational.ae

In a city whose skyline is dominated by new and exciting architecture, it takes something special to attract as much attention as the gently tapering Al Bahr Towers.

The new Abu Dhabi Investment Council building will feature a computer-controlled facade made up of more than 2,000 translucent units that will open and close as the sun moves over their surface. The result is a reduction in overall energy consumption and carbon footprint. Andrew Henderson / The Nation
The new Abu Dhabi Investment Council building will feature a computer-controlled facade made up of more than 2,000 translucent units that will open and close as the sun moves over their surface. The result is a reduction in overall energy consumption and carbon footprint. Andrew Henderson / The Nation

Standing 145 metres above the junction of Al Saada and Al Salam Street, the landmark twin towers will be the new purpose-built headquarters of the Abu Dhabi Investment Council (ADIC). These 25-storey celebrities have already been named as one of the most innovative buildings in the world, the subject of intense discussion in the architectural press as well as featuring on international radio and TV programmes.

Still under construction, they have already featured on the Chicago-based Council on Tall Buildings and Urban Habitat’s “Innovative 20” list of buildings that “challenge the typology of tall buildings in the 21st century”. Not bad for a project that is still several months from completion.

Yet all this excitement has largely passed residents by. Even those in the emirate’s design and construction industries have been hard-pushed to identify the brooding, dark grey structures that greet drivers as they approach Abu Dhabi’s downtown.

Not for much longer. Soon the towers will take their place alongside the Burj Al Arab, Burj Khalifa and Yas Marina Hotel on the list of UAE buildings that command instant and widespread public recognition. Why? Installation has finally started on the building’s key structure, a computer-controlled, robotic facade made up of more than 2,000 translucent, parasol-like units that will open and close as the sun moves over their surface. In short, the Al Bahr Towers will be clothed in a moving, protective veil.

The building’s architects describe this complex facade as a “dynamic mashrabiya”, a 21st century reinterpretation of the carved and perforated screens that traditionally provided shade and privacy to Islamic houses throughout the Middle East. Designed by the engineering firm Arup and architects from the London studio of Aedas, the international practice responsible for Dubai’s metro stations and Abu Dhabi’s Manarat Al Saadiyat, the building manages to draw deeply on Islamic geometry and heritage for its inspiration while remaining modern and avoiding mimicry or pastiche.

For Peter Oborn, the project director, and deputy chairman of Aedas, the clearest guidance came from the original client brief.

“ADIC wanted a design that would reflect the cultural traditions and architectural heritage of the Middle East, while setting new environmental standards of design,” he said.

Mr Oborn and the project’s lead designer, Abdulmajid Karanouh, resolved to create a building that was as environmentally friendly and energy efficient as possible, avoiding the mistakes made in generations of buildings throughout the region.

One of the biggest challenges was to achieve all this while meeting the expectations associated with a high-status, high-rise glass tower; a building type thought inimical to sustainable construction given local climatic conditions.

For Mr Karanouh, it was immediately clear that the building required protection from the sun.

“If we were really genuine about creating an environmentally friendly building, we needed to find a way to protect the building from direct sunlight,” he said.

Traditional shading devices, however, were not a viable option. “Permanent shading would have compromised visibility and views from inside the building, while lighter shading would have compromised the energy performance of the building itself,” he said.

The use of heavily tinted and highly reflective glass, a common practice in the region, was also out of the question. Not only would this distort views from inside the building, it would also increase the need for environmentally costly artificial light.

Mr Karanouh’s solution, the dynamic mashrabiya, allowed Aedas to achieve the same kind of performance as a building with a facade that was largely solid. The result is a reduction in the building’s overall energy consumption and carbon footprint by 20 per cent while in localised areas on the south side of the tower, which benefit most from the mashrabiya’s protective veil, savings are closer to 50 per cent.

The Al Bahr Towers are protected on their east, south and west sides by the mashrabiya. Each of the system’s 2,099 units is constructed from 15 components that form a triangular, Teflon-coated, fibreglass mesh set in an aluminium and stainless steel frame. Designed to withstand earthquakes and winds of more than 240 kilometres per hour , some of the units measure 6 metres by 4 metres and weigh almost 600 kilograms. Given their number and size, it is not surprising that the struts that attach the mashrabiya on the facade weigh 240kg each.

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