More than just hot air

Using traditional Arabic wind towers could have huge energy savings

ANALYSIS, Projects

A traditional Arabic form of architecture could be a solution to the huge energy usage for air conditioning in hot countries, according to a UK-based academic.

The wind tower – a fixture of Middle Eastern architecture for almost 1,000 years – could provide 21st century sustainable design solutions, said Ben Hughes, associate professor of building physics at Leeds University.

The historic Creek area of Dubai has some of the greatest concentrations of the towers in the Middle East.

“They used to build the towers as tall as possible (to) capture the air at high speed. As it hits the tower, there’s a wall that runs down the centre of it that forces the wind down into the building,” said Hughes.

“The higher up you go, the faster the airspeed is.”

The build-up of positive pressure inside the structure automatically creates negative pressure on the outside, which means that internal stale air is drawn away.

“It creates a siphon effect,” Hughes explained. “It pushes air into the building and sucks stale and used air out the other side of the wind tower.

“In arid climates such as the Gulf, then a reduction in air-con consumption of around 60% is possible.”

The professor said he felt the towers could be easily assimilated into contemporary architectural designs – but added that tall buildings offer some challenges.

“Wind towers can be bespoke manufactured to meet any design requirements, either from traditional materials or sheet metal depending on the aesthetics of the project,” he said.

“Similarly, the height of the tower can be adjusted by altering the angle of the air inlet vents to compensate.

“It follows similar principles of an aircraft where the air pressure is varied by altering the angle of the wing.

“Tall buildings are not necessarily the best use of the system as supplying the lower floors can prove problematic due to the length of ducting required and needs careful design to include significant buoyancy effect to assist the airflow.

“Wind towers have been used extensively in recent years, although often as part of a mixed ventilation solution rather than a standalone ventilation system.

“Masdar has a large wind tower and is the most recent large-scale design.

“However, Qatar University incorporated wind towers during its construction circa 1970.”

Hughes said the heritage aspect of the design is important as well.

“In a period of development it is always important to embed the local tradition and culture to ensure the region’s identity remains intact,” he said.

“The danger is by employing tried and tested techniques from around the world, the knowledge base of local architects and engineers is lost to ‘new technologies’.

“I based my research approach on that of Hassan Fathy (20th century Egyptian architect who championed Arabic design over imported western ideas), that we should always look at traditional design solutions before looking at new technologies," said Hughes.

He added that the construction of a tower is simple, but the design “takes a little time and thought”.

He said: “Essentially, if the area is prone to low wind speeds then the device needs sufficient buoyancy to drive the flow. An understanding of occupancy patterns and heat gains will provide this information as will historic weather data.

“Once the design is set the actual construction and installation is straightforward – there are many commercial partners who will undertake both the design and construction.”

Hughes leads a dedicated research team at the UK university, which is now looking to patent research on its technology.

He said: “My team at Leeds consists of 12 PhD students, two-post doctoral fellows and a full time laboratory technician and has recently integrated heat pipes into wind towers to act as heat recovery in the UK, providing pre-heated air into occupied space in times of low external temperature.

“We have also filed a recent patent for our new cooling technology, which integrated a cooling loop into a traditional wind tower, therefore pre-cooling the air for the occupied space.

“We are now focussed on bringing this onto the commercial market for deployment in the Middle East in 2014.”

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