Halo is an open building, a strategic assemblage of parts, that connects (city and water), activates (green corridor), contains (the garden as a small urban paradise) and exposes (simultaneous display of all possible disasters). As the project is in a potential green corridor we planned it as a hortus conclusus –a walled garden- that links three zones; the urban, the green and the water. We made the garden wall like a programmed loop, elevated on top of three active islands and a forest of thin columns. The garden is an open, accessible and activated part of the green corridor for all citizens and visitors of the building. From the sky the project reads as a clear urban logo for Istanbul.
Before starting the building design we have improved the context and environment of the project, which is very well connected to all kinds of infrastructures. Its generic character as an airport and business environment made us design something completely different. Istanbul has an average green space of only 6 m2/person. It is far behind most European cities that have an average of 20 m2/p. Amsterdam has 45 m2, Rome 45 m2, Stockholm 87 m2, even New York has 29 m2 and London 27 m2/p. Therefore we propose a repair of the broken corridor along the Ayamama creek that comes from Basaksehir and flows down into the sea. It has great potential if we plan green public space along the creek. This makes an urban green corridor that also enhances the competition site.
The loop is designed as a powerful urban object. This is the reason for its minimal architecture and abstract white finish. It holds the edutainment programs in one flow of transparent interior pavilions. All edutainment programs with simulation rooms are simultaneously displayed in the loop. The exhibition is not in a room but goes along the circulation space and offers the public all necessary background on a free flow trajectory along the pavilions. Information is exchanged through interactive led touch screens embedded in the glass envelopes of the pavilions. The subtly warped top of the loop holds the cafe with an impressive panorama over the complete environment with airport and coastal waters.
The three islands are activators of the green corridor. The urban island is situated at the street side and is finished in asphalt. It holds the sun-protected parking and the main entry facilities and office spaces. Two islands are situated in the green corridor with skins of grass. One holds the planetarium and the shelter, the other holds the auditorium.
The 65-m diameter urban garden is open to the public. It has a micro climate which is shaded in summer and wind protected in winter. It offers a display of all edutainment programs in the loop and different activities like reading, walking, cycling, lounging and urban sports like skating, etc. As the project is very well connected to main infrastructures, the garden has the potential to host big public events like pop concerts. Opposite the entry island a stage is planned with a huge video screen integrated in the inner edge of the loop.
All programs are functionally integrated within the complete project, but some can also function separately. The parking, auditorium, restaurant and planetarium are all integrated with the loop but have their own dedicated entries as well.
STRUCTURE AND DISASTER PREVENTION
In order to guarantee earthquake resistance, the project is symmetrical, light weight, resistant to sideways loads and it is low compared to its width. The loop is point symmetrical to minimize sideways shifts and/or rotation instability. In order to reduce the loads it has a lightweight steel structure with a top and bottom part of internal beams that taper from the center to the edges. Both top and bottom have an exterior cladding of thin, prefab, white fiber glass reinforced concrete panels. In order to create an open, monumental interior space and to reduce structural supports, two outer lines of columns hold the top and bottom apart. Radial and lateral trusses take lateral and rotation forces. The facades are made of vertical glass sheets, mounted at the bottom and top. The vertical seams are silicon joints that can take deflections caused by wind pressure. The islands below are carriers and stabilizers of the loop and made of steel truss portals with robustly fitted column-floor connections and inclined sides to withstand lateral forces. Where islands are absent, the loop is supported through a forest of thin commuter columns that can take earthquake shifts through high deformability and flexible head and foot details. In terms of emergency escapes, all three islands facilitate exits in four locations with a maximum 70-m. distance between exits. The shelter is located halfway the loop, together with the exit along the planetarium. In case of fire, the smoke extraction goes exterior through vents in the ceiling.
CLIMATE CONTROL AND SUSTAINABILITY
A total of four HVAC units are located in the three islands with air ducts running vertically through four specific columns. The ceiling of the loop takes care of horizontal air ducts. As the loop is lightweight, it has little accumulation. Therefore air treatment takes care for cooling and heating of the interior climate. All glass facades of the islands and the loop have photovoltaic ventilated glass. The facades do not need further sun shading. From the cavities of the glass facades warm air is extracted into the ceiling towards heat exchange units. These units capture the energy for two warm-cold water underground storage basins for air treatment during respectively winter and summer periods.