Wind Towers - Bahrain

Bahrain World Trade Center
Manama, Bahrain

The Bahrain World Trade Center forms the focal point of a master plan to rejuvenate an existing hotel and shopping mall on a prestigious site overlooking the Arabian Gulf in the downtown central business district of Manama, Bahrain. The concept design of the Bahrain World Trade Center towers was inspired by the traditional Arabian “Wind Towers” in that the very shape of the buildings harness the unobstructed prevailing onshore breeze from the Gulf, providing a renewable source of energy for the project.

The two 50 storey sail shaped office towers taper to a height of 240m and support three 29m diameter horizontal-axis wind turbines. The towers are harmoniously integrated on top of a three story sculpted podium and basement which accommodate a new shopping center, restaurants, business centers and car parking.

The elliptical plan forms and sail-like profiles act as aerofoils, funnelling the onshore breeze between them as well as creating a negative pressure behind, thus accelerating the wind velocity between the two towers. Vertically, the sculpting of the towers is also a function of airflow dynamics. As they taper upwards, their aerofoil sections reduce. This effect when combined with the increasing velocity of the onshore breeze at increasing heights creates a near equal regime of wind velocity on each of the three turbines. Understanding and utilising this phenomenon has been one of the key factors that has allowed the practical integration of wind turbine generators in a commercial building design. Wind tunnel testing has confirmed how the shapes and spatial relationship of the towers sculpt the airflow, creating an “S’ flow whereby the centre of the wind stream remains nearly perpendicular to the turbine within a 45° wind azimuth, either side of the central axis. This increases the turbines’ potential to generate power whilst also reducing fatigue on the blades to acceptable limits during wind skew across the blades.

The specific architectural forms of the Bahrain World Trade Center towers were borne from using the nautical expression of a sail to harness the consistent onshore breeze, potentially to generate energy using wind dynamics, as well as to create two elegant towers for Bahrain, which would transcend time and become one of a kind in the world.

Building Integrated Wind Turbines
Wind Analysis

Three wind turbines have been integrated into the building to generate electricity. Horizontal axis wind turbines are normally pole mounted and turn to face the direction of the wind thus maximizing energy yield. The practical application of such turbines to buildings in variable direction wind climates is therefore very difficult. The majority of architectural studies deploying building-integrated, horizontal axis turbines deploy the principle of a fixed turbine as in the case of the Bahrain World Trade Center. Development for vertical axis wind turbines is encouraging and of course they benefit from the advantage of being truly omni-directional. However, at the time of design development for this project, large scale proven vertical axis turbines were not available for building applications.

The fixed horizontal turbine suffers the drawback of only being able to operate with wind from a limited azimuth range, if problems with blade deflections and stressing through excessive skew flow are to be avoided. From the outset of this project, the shape of the towers has been designed to capture the incoming wind and funnel it between the towers.