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Karachi rising

Pakistan's biggest building will help the nation announce its arrival on the global stage.

NEWS, Projects

Pakistan's biggest building will help the nation announce its arrival on the global stage.

In the Middle East, it's easy to get blasé about ‘iconic' buildings, which seem to spring up on a weekly basis. Other regions don't necessarily have the same economic power, the same business cache, or frankly, the same media coverage as the Gulf.

So when one of these other regions begins construction of a building that's nearly double the height of its current tallest, it's worth sitting up and taking notice of a genuine icon.

The busy port of Karachi, Pakistan, is home to around 17 million people and-because of population and myriad socio-political factors-is one of the more challenging places in the world to create a world-class design. Aedas' Karachi Port Trust (KPT) Tower Development is taking on those challenges, and may even help boost Pakistan's position on a world stage.

At 80 storeys high, the tower is a first for Pakistan, which has never built anything over 25 storeys. Aedas was selected via competition, largely because of their previous expertise in similar projects.

"We had to put forward a proposal of how we'd handle it and examples of previous designs, so the competition was in terms of the quality of the way we'd handle the project and execute it," explains David Kingdom, project director at Aedas.

Pakistan suffers from its share of both political and environmental instability, which means a project the size of the KPT Tower must be designed particularly sensitively in order to cope with the extremes to which both man and meteorology subject it.

"The biggest problem in Karachi during monsoons is that it gets flooded. Their drainage infrastructure can't cope with it," explains Kingdom.

Given that the building makes use of underground parking, it is particularly important for the project to have a sound strategy for preventing floodwater from entering the car parks. "You need a bundled perimeter and over the threshold runways you have these rising dams that block the entranceway," says Kingdom.

Other problems include the very real threat of an attack by any one of Pakistan's myriad militant groups. As the biggest building in the country, the KPT Tower could be considered a potential target during periods of social unrest.

With 12,000 people using the building on a daily basis and with most of them arriving and leaving during morning and evening peak hours, complex computer simulations had to be conducted to find out how best to monitor such vast numbers of people without causing delays.

To that end, the building will have 14 exits to cope with the potential numbers of people. "We simulated it about six times before we got it right. We had to enlarge the lobby area significantly to ensure that at peak rush hour, people weren't queuing outside," says Kingdom.

The building is to be constructed from reinforced concrete, which will undoubtedly provide challenges in and of itself. "I've never built anything this high in concrete," says Kingdom, who explains that getting an acceptable quality of concrete in Pakistan has traditionally been a problem as well. Concrete, after all, provides the building with a degree of fire-proofing-a vital component in a post-9/11 world and in a country familiar with both social and political conflict.

Adding to the challenges of building KPT Tower is its location on an active seismic zone. Because of the height of the building, a tune mass damper is required to keep the tower stable. "You need to put a pendulum arrangement on the upper floor of a building, which can be done with a mechanical weight, or as we're doing it, with a whole floor of water..." says Kingdom.

"[The water] is pumped from one side to another to compensate for the swaying of the building." The water floor also adds another component of fire safety to the building. "That tank is also used to pressurise the sprinkler system," explains Kingdom.
 

Efficient design

In keeping with the growing worldwide trend for sustainability, KPT Tower will also include a number of design features aimed at reducing energy use. However, Kingdom points out that a sustainable building is desirable in Pakistan from more than just a practical level. "The country is starved of energy supplies," he says. "Fortunately, the government is extremely conscious that natural resources are limited and [sustainability] has to happen."

As a result, the design of the building is based on information gained from a very intensive process of energy-saving simulation. "We have an advanced modelling group in our London office, which did some very complex simulations to look at the whole sun-path geometry of 365 days of the year, every hour of the day," explains Kingdom.

The results of the simulations mean that the building can have a completely shaded external envelope, which dramatically reduces the cooling load on the building.

The solar shading is provided by large cantilevered solar shades, some of which extend as much as five metres from the façade. Full solar shading also means that more glass can be used in the building's façade, which assists in the tower's durability.

"One of the design challenges within Karachi is that it's a marine atmosphere, which is very aggressive in terms of corrosion but there is also a high level of pollutants due to the traffic of 17 million people," explains Kingdom.

The shading also means that low-E glass can be used on most of the elevations.

Cooling for the building will be partially provided by the significant wind load from the Indian Ocean. "The vortices around the building have a continual circulation of moving air that keeps the surface glass temperature quite low," explains Kingdom. Plans also exist for a 40-metre wind turbine on the roof, although at this stage in the design, this feature is purely speculative pending an economic analysis.

The building's sustainability is further augmented through its water preservation and recycling systems.

Rainwater collection tanks are a standard feature in Pakistan and, according to Kingdom, grey water will be used for toilets and irrigation. "The outfall would also be recyclable for drinking, but we won't be doing that because of the psychological issues related to that," explains Kingdom.

The level of sustainability for KPT Tower will be evaluated by the UK's Building Research Establishment's Environmental Assessment Method (BREEAM), with an aim for a rating of ‘Excellent'.

Danton Phillips, the commercial director for Aedas on the project, has indicated that US LEED and Abu Dhabi Estidama accreditation could also be considered since the building is intended to appeal to the global market.
 

Local knowledge

An important aim of the project is for KPT Tower to act as a springboard for future architectural development in Pakistan. ‘Knowledge transfer' has proved a particularly important part of the design process, and as a result, the Aedas design team worked very closely with local partner Ali Arshad Associates-soon to be Aedas Karachi-in order to create a design appropriate to the cultural context.

"We could have come in as an arrogant set of architects from outside, but instead we took them gently step by step," says Kingdom. Aedas also involved three eminent Pakistani architects, Tariq Hasan, Habib Fida Ali and Surti & Partners, to participate in design workshops. "That created a lot of cultural support because there were things there that we might have done wrong and not understood the culture quite right," says Kingdom.

Although the building has been designed and modelled through computer simulation, local architecture still played a vital role. According to Kingdom, the crown of the building is inspired by Islamic architecture.

The height of the building has meant adopting architectural protection strategies that have been used in other markets but are somewhat unusual in Pakistan. For example, every 18 floors, there is what Kingdom describes as a reinforced concrete ‘Catherine wheel', which provides a shelter point during a phased evacuation.

Those leaving the building can corral at these refuges before using a lift to escape the building if necessary. All of the lifts are contained in a thick high-density fire-resistant concrete core.

The extraordinary nature of this element meant Aedas faced some unforeseen challenges when dealing with the Karachi fire authorities. "The fire chief's first reaction to the building was that he doesn't have a fire tender with a ladder big enough," says Kingdom.

However, Aedas worked closely with the fire authorities to advance their abilities to deal with fires in tall buildings by explaining the design principles and evacuation policies.

That collaborative safety effort is consistent with the Aedas team's approach to the entire project. "[KPT Tower] is seen as a symbol that this country is coming together. [The Pakistani authorities] are extremely proud to be able to this," says Kingdom.

"During the process, we made a lot of friends with people like the governor, the lord mayor, the head of the building control authority and the fire authority," adds Kingdom. "We feel we've helped them grow and I know I've made some good friends who'll certainly assist us in mapping the way forward in the future."

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