Council on Tall Buildings and Urban Habitat
 

The Index, Dubai
Posted September 2012
The Index was recognized as "Best Tall Building Middle East & Africa"  in the 2011 CTBUH Awards Program.
Other Featured Tall Buildings

“The Index presents a new environmental icon for the Middle East, showcasing important passive strategies of orientation, core placement and shading.”
- Werner Sobek, CTBUH 2011 Awards Juror, Werner Sobek Group

Location
Dubai
Completion
2010
Height
326 m (1,070 ft)
Stories
80
Primary Use
Residential / Office


Owner/Developer
Union Properties

Design Architect
Foster + Partners

Associate Architects
Khatib & Alami; Woods Bagot

Structural Engineers
Halvorson and Partners;    Bruechle, Gilchrist & Evans
MEP Engineers
Roger Preston & Partners; WSP Group
Project Manager
Edara Confluence

Contractor
Brookfield Multiplex

The Index is a model for developing sustainable built environments in the Middle East region, as well as other similar climatic environments elsewhere in the world. Despite the minimalism in design, the tower offers a reassurance on the ability of modern buildings to draw on the natural strengths of their environment. The compelling feature of the tower is its intelligent integration of space, sunlight and shades to minimize solar gains.

The building takes a particularly interesting approach at its base, with only its structural fins and cores coming all the way to the ground, while the rest of the space opens up in an open-air shaded atrium with large pools which create a cool micro-climate around the tower’s entrances. This is a stark contrast to the fully-enclosed glazed lobby spaces typical of most tall buildings and a further example of The Index’s relationship to its local climate which allows for this openness.

The Index occupies a prominent corner site within the Dubai International Finance Center, a financial district intended to establish Dubai as an investment market, and to provide a catalyst for further economic growth in the region. Balancing a mixture of residential, commercial and social uses to support the Finance Center and wider community, the building represents a vertical city quarter with a population of around 6,000 residents and workers on its 20,000 sq m (215,278 sq ft) site.

The Index exploits the sustainable paradigm of maximizing the environmental benefits of a compact, high-rise form with an efficient design that reduces the need for mechanical cooling systems and artificial lighting. Oriented east to west, the building is positioned obliquely off-grid, strategically designed to accentuate the metropolitan view of Dubai International Finance Centre on the north side and the Dubai cityscape on the south. By turning away from the city axis, the building is also able to reduce solar gain; the building’s core mass absorbs heat and limits its reliance on mechanical ventilation. A system of sunshades shelters the interiors on the exposed south elevation.

Figure 1. Façade detail of sunshades
Entrance is via a dramatic four-story atrium with the tower sitting on a landscaped podium, which provides shaded pedestrian routes through the site and a range of places to eat, shop and socialize. A 200-meter-long (656-foot) pool wraps around the edge of the tower: its tranquil inlets help to cool the transitional spaces, reflect indirect light and animate the entrance with the sound and motion of water cascading over the smooth stone shingles. The effect is a dramatic sense of arrival.

The perimeter of the site is marked by a colonnaded sequence of shops, and the space created between the tower and glazed façade defines a semi-private garden, a shaded grove and seating where office workers and residents can relax. The landscape of the podium draws on local species of date palms, which thrive in the desert climate and require less irrigation. Forging links with the wider master plan, the retail podium also has a lower level connection to a large internal mall, which is accessible throughout the Finance Centre.

The floors are supported by four A-frame concrete “fins” that taper as they rise, creating a slender profile that reveals the building’s structural system and internal organization. The inner and outer edges of the structural fins have a ribbed effect, created by pre-cast concrete panels which are colored a light grey—this finish reduces the visual impact of sand settling on the façade, thereby minimizing maintenance requirements and energy use.

Figure 2. Open-air lobby space with pools

The challenge for the design of The Index tower was to bring together a combination of retail, residential and commercial spaces within a single tower, without compromising each function. The form of the tower articulates these different functions externally—the design balances the needs of offices and high quality apartments within a single, coherent structure with a relatively compact footprint and very slender profile.

The twenty-five floors of office space are concentrated at the base of the tower, so that the living spaces above can take advantage of views towards the coast. The different functions are separated by a spectacular double-height, fully-glazed sky lobby, articulated externally as a horizontal break in the façade. Residents’ facilities include a lounge, restaurant, pool and health club and the tower is crowned by twelve luxurious duplex and triplex penthouse apartments which feature private swimming pools. In addition to balconies, the tower incorporates eight large terraces spaced out on the slender edges of the building—these are structural elements, which have been fully utilized to take advantage of the spectacular views from the tower.

Figure 3. Cascading water surrounding tower base
Placing the lift cores on either side of the building, where they are clearly visible externally, ensures that orientation is clear. Each core gives access to half of the floor plate and signage marks the east and west zones accordingly. A small central lift core, serving 40 levels of apartments, rises to the sky lobby, where a local lift core transports residents to their individual apartments. The different functions contained within the tower are echoed in the treatment of lift areas on the office and residential floors: the lower level lift lobbies are clad in highly reflective stainless steel, while the upper floors are neutral, appropriate to a more domestic setting.
Figure 4. Overall view from the south
The environmental strategy is progressive and integrated with the tower’s architectural design: the open atrium at the base of the building combines shading with a large water feature to create a cool microclimate; each apartment can be naturally ventilated; and large glazed areas on the office floors maximize natural light, but are controlled by external shading on areas with high solar gain.

Each office floor plate comprises three 27x27 meter (89x89 foot) column free bays. These long span structures allow maximum flexibility for space planning, so that the levels are suitable for large international financial corporations or can be subdivided for multiple tenancies.

Related Links
CTBUH Skyscraper Center Profile:
The Index

The Index was recognized as the Best Tall Building Middle East & Africa Award Winner in the 2011 CTBUH Awards Program.
Download The Index 2011 CTBUH Awards Book section
2011 CTBUH Awards Book

Videos:
Best Tall Building Middle East & Africa Symposium Video: The Index

The CTBUH would like to thank Foster + Partners for their assistance with this article.
Photography © Nigel Young / Foster + Partners