4.1.2. AL BAHAR TOWERS, ABU DHABI

4.1.2. AL BAHAR TOWERS, ABU DHABI

Architect: Aedas architects

Year of construction: 2009-2012

Floors: 27 + 2 basement

Floor area: 56.000 m²

Location: Abu Dhabi, United Arab emirates

Climate: hot and dry climate, and highest temperature: 50 Degree Celsius

The city has intensive sunshine all year long with fewer chances of rain. In such extreme weather, environmental design is that the priority on the planning agenda.

CONCEPT

• The design concept is based on the fusion between bio-inspiration, regional architecture, and performance-based technology. • Circles and orbits are used to reflect the concept of unification and unity evident in nature.

The design principle is to realize a performance-oriented, culturally relevant, technologically advanced, and aesthetically intriguing building.

Planning is based on six tangential arcs, taken from three intersecting circles; a pattern which forms the basis of nearly all geometric configurations known to the region.

The design for the project began with two simple cylinders because the circular plan giving the foremost efficient floor area usage while also creating the best volume with the smallest amount surface area which can highly reduce the sun exposure area.

Figure 22 : Building layering model

An integrated building model consisting of both the geometry of the building and the mashrabiya shading devices

DESIGN ELEMENTS

• The design is based on the concept of adaptive flowers and the "mashrabiya" - a wooden lattice shading screen. • A dynamic and sensitive shading screen acting as 'mashrabiya‟, and secondary skin filters the light and reduces glare. • It is powered by renewable energy derived from photovoltaic panels. • It wraps a giant lattice almost two towers completely except for the area north-facing facades.

OPERATION

• As the sun rises in the morning in the east, the mashrabiya along this side of the building will begin to close, and when the sun moves around the building, all vertical strip mashrabiya moves with the sun. • At night all screens fold, allowing more of the facade.

TORRES - "COCOON BUILDINGS"

• It is based on a pre-rationalized geometric shape, tuned via parametric design tools to achieve the optimal ratio of the surface between the walls and floor. • The form of the towers is optimized to complement the shading system.

Figure 23 : Screens Al- Bahar tower screen’s module

INTELLIGENT FEATURES

• Each unit comprises a series of panels stretched PTFE (poly- tetra- fluoroethylene) and is driven by a linear actuator to progressively open and close once per day, in response to a pre-programmed sequence that's calculated to avoid direct sunlight to from the instant it hits the facade. • Computer-controlled, • Operates as a curtain wall, • Two meters of the exterior facade of buildings, in a separate frame • Each triangle is coated with micro fiberglass • Programmed to respond to the movement of the sun • The whole system is protected by a variety of sensors that open the units in case conditions change or rise to cloud winds. • Geometric patterns that make up this giant screen include more than 1,000 mobile elements that contract and expand during the day, depending on the sun position.

PHOTOVOLTAIC CELLS

• Roofs facing south each tower incorporate photovoltaic cells • Generating approximately five percent of the entire energy required renewable energy sources, used for heating water • The towers have been one of the first buildings in the gulf that received a leed silver rating.

Figure 24 : Sun-shading panels Figure 25 : Transformation of Panels

EFFICIENCY

• It is estimated that the screen reduces solar gain by more than 50% and reduces the need for air conditioning. • Screen's ability to filter light has allowed being more selective in the choice of glass. • This allows us to use more naturally tinted glass, which allows more light inside and less need for artificial light. • The intelligent facade, together with solar thermal panels for hot-water heating and photovoltaic panels on the roof, minimize the need for internal lighting and cooling, altogether reducing total carbon dioxide emissions by over 1750 tons per year.