GREENwichFORUM

by Ken Yeang on 04-08-09

Zorlu Ecocity

Zorlu Ecocity is a mixed-use development on a 9.6 ha site located at the southern extremity of Buyukdere Street in Istanbul. The plan is conceptualised as an ecological city within a city in line with the polycentric planning strategy of the Istanbul Metropolitan Planning and Urban Design Centre, which aims to multiply the number of urban centres throughout the Marmara region to relieve pressure on Istanbul historic core.

The planning brief permits up to 588,850 square metres of accommodation, at a plot ratio of 2.8, including office towers, residential towers, two hotels, serviced apartments, and resort-style elderly accommodation above a three storey retail complex that includes a market, a Cineplex, health centre, fitness club and convention centre. Six thousand cars are to be accommodated within a seven-storey deep basement.

The concept takes the form of 14 towers ranging from 8 to 26 storeys. The roof silhouette of the towers is shaped to collectively form a gentle curve reflecting the rounded summits of the seven hills upon which Istanbul is located. The form is not unlike a ‘citadel’ overlooking the Bosphorus alluding to the proud history of Istanbul as the former capital of the Byzantine, Roman and Ottoman Empires. Consideration has been given to the silhouette of the towers particularly when viewed from the south and east as a backdrop to the Bosphorus and from the south west and west when approaching the site by car or bus from the E5 Motorway or D100 Highway. Conceptually the design can also be read as a ‘visual link’ connecting Europe and Asia.

The plan form of the development resembles a ‘horseshoe’ opening out to the south and physically connecting to the heavily wooded Ortakoy Valley. Responding to the perceived lack of public space in Istanbul the proposal creates a large urban plaza some 50 metres wide and up to 35 metres broad.

The opportunity is taken to create a pedestrian link via an overhead footbridge to the Zincirlikuyu Area and specifically to the Garreteer Metro Station. The Metro affords access toLevant to the north and south to Taksim Square.  A pedestrian underpass is proposed in the south west corner of the site, passing beneath the D100/E5 Highway and linking to bus stops. Elsewhere there will be improved footpaths to the residential enclaves located to the southeast and northeast of the site.

The proposal regenerates a ‘brownfield’ site in an accessible location close to the urban core. It integrates with the existing urban fabric and city life. Links are proposed to existing commercial and housing development in the Sisli-Gayrettepe-Esentepe area to the west, to the Gayreteppe Metro Station, to the Zincirlikuyu area and to Levant Buyukkdere Street

A symbol of Istanbul’s aspiration, the design for Zorlu Ecocity is a contemporary response in architecture to the city’s re-emergence as a cultural nexus exemplified by its selection as European Capital of Culture in 2010. The design embodies new spatial configurations. The result is a vibrant focus for urban life relieving pressure on the historic core of the city. The internal planning and pedestrian circulation system within the shopping mall is a modern interpretation of the Grand Bazaar and the lanes that radiate from Istiklal Caddesi.

Ecological connectivity

The masterplan, is derived, first and foremost, from an intensive interrogation of the site. The analysis revealed that the site contains fragments of a sensitive ecosystem and adjoins a steep valley containing a robust ecosystem. The potential to establish ecological connectivity became the dominant consideration in reprogramming the site. There are a number of ecological features that assist in achieving this connectivity.

Central to the concept is the principal of ‘ecological bridges’, to reconnect the existing ecosystem. Eco-Bridges are concrete structures bridging the 10-metre wide perimeter road and connecting the podium roof, which is planted with indigenous species of trees and shrubs, to the landscape on the periphery of the site.

Another feature is the Eco-Cell, a continuous vegetation-covered ramp at the heart of the development that descends from ground level to the lowest basement level bringing daylight, natural ventilation and greenery to the deepest part of the development. In effect a deep ‘valley’ is constructed. It is a sustainable passive ventilation strategy that removes polluted and warm air at no cost. The vegetation will help to replenish fresh air in the subterranean space and contribute to lowering the ambient temperature in summer. A rainwater storage cistern is incorporated at the base of the eco cell and a retention pond is located at the southern edge of the site. They provide ‘grey’ water for irrigation purposes being recycled to the upper level of the towers and thereafter infiltrating the green walls and vertical gardens by gravity.

Vertical gardens or ‘green walls’ clothe the vertical surfaces and connect the landscaped podium to the roof of each tower. A proprietary system is employed which supports the vertical landscaping. Elsewhere a feature which we term ‘Green Fissures’ is created in the building façade to promote planting. Roof gardens employ a Sedum roof system and in a similar manner to the green walls assist in balancing the biotic and abiotic content of the buildings.

Sky courts are integrated into each tower and act as ‘gardens in the sky’. They serve as interstitial zones between the interior and exterior with usable balcony or terrace areas that open from habitable rooms in residences, offices and hotel suites. Sun Shading is designed to respond to the specific sun-path diagram.. Wind shafts are integrated into the towers and relate to lift cores/lobbies. This is a passive ventilation strategy to introduce natural ventilation, provide a comfortable internal environment, and reduce running costs. Wind turbines will be mounted vertically with a support frame tied back to the structure and located immediately beneath the vegetated roof.