Green twist on traditional building methods

Two towers being built in Abu Dhabi showcase a unique approach to construction in the region by applying state-of-the-art design to traditional Middle Eastern features.

The twin towers under construction on Al Saada merge an ancient Islamic architectural form with state-of-the-art technology to create one of Abu Dhabi's most advanced "green" developments.
The 25-storey glass towers, which will serve as headquarters for the Abu Dhabi Investment Council (ADIC), will feature what the project architect Peter Oborn calls a "translucent veil" wrapping the east and west faces. The surfaces are a homage to mashrabiya, the traditional complex wooden lattice screens found in many Middle Eastern buildings.
But there is a modern twist: as the sun moves across the sky, each of the 2,000 geometric pieces will operate like parasols, opening and closing to shade the surface of the buildings.
This will be the first time movable facades have been used on this scale, says Mr Oborn, the deputy chairman of Aedas.
The result will be a 50 per cent reduction of the sun's impact on the building's skin, according to the company. That means less air conditioning needs to be used and less need for tinted glass, allowing more natural light into the offices, producing a "significant reduction in electrical energy consumption".
The project, dubbed Al Bahr, also creates a new icon for the entrance to the island at a time when the emirate is eager to establish itself as a leader in green development.
"I hope history will show this building as being reflective of a point in time in the evolution in sustainability in the Gulf region," says Mr Oborn.
Aedas, based in London, is one of the world's largest groups of architects and won a 2007 competition to design the headquarters. At the time, the general charge from the ADIC was simply to create two "landmark" towers, with few specific guidelines other than to incorporate the region's "architectural heritage".
Aedas chose to move away from the more bulky designs popular in the UAE. "We didn't want to produce another monster," Mr Oborn said.
Almost every element of the exterior was developed with the sun in mind. The designers incorporated circular forms, which naturally reduce direct exposure and the roofs were slanted at an angle to maximise the efficiency of sunshine-gathering photovoltaic cells to produce electricity.
The top and bottom of the towers are sculpted in such a way as to increase the floor space in the centre while reducing the number of surfaces directly facing the sun. To further minimise the effects of solar rays, room was created on the upper floors for gardens, resulting in open-air areas for tenants to enjoy.
Researching the traditional architecture of the region, the designers settled on mashrabiya, a feature dating from the Middle Ages. Known for their intricate carvings, mashrabiya provided both privacy and cooling.
But the designers soon realised mashrabiya alone would not achieve their goals.
"Initially we thought of using fixed shading devices but it would have to be fixed for the worst case," says Mr Oborn.
In other words, the mashrabiya would provide too much shade, blocking views when there was little direct sun. From there, the idea of electronic mashrabiya was born.
"The beauty of this is its simplicity," Mr Oborn says.
Sensors will constantly measure weather conditions, directing the movement of the mashrabiya. Instead of set schedules, the elements will open and close depending on each day's weather, adjusting for occasional storms or cloudy days.
Those within the towers should barely notice the changes, which will happen gradually throughout the day.
"It will be a bit like having the blinds drawn," says Mr Oborn.
Once the designers determined the system could work on a large scale, the challenge was to figure out how much it would cost to manufacture. To help keep prices down, small, mass-produced motors commonly used in aircraft were incorporated in the design. And existing management software will control the action.
Each of the 2,000 elements will operate individually; and are easily replaced if they break down.
Earlier this year, a prototype was built and installed to demonstrate the system to ADIC officials.
"The mock-up proved the design was robust," says the project director Bryan Hamilton, resulting in what he describes as his moment of "biggest relief".
"We didn't have to change the design at all after the mock-up," he adds.
If the mashrabiya achieve the expected energy efficiencies, the system could provide a model for future developments in the UAE. Last month, the Department of Municipal Affairs moved to restrict developers from building glass towers unless they can develop methods to conserve energy.
Construction crews expect to begin attaching the brackets for the mashrabiya on Al Bahr in about six weeks, with installation of the apparatus starting a few weeks later. The entire complex is scheduled to open in 2012.
The hope is that the project "reflects the aspirations of the UAE and integrated architecture in a new way, in a new vernacular", says Mr Oborn.
[e-mail]