1 Bligh Street

Australia’s first double-skin façade high-rise office building will be built near Sydney’s Circular Quay. The transparent, elliptical structure will be constructed on the corner of Bligh, Bent and O’Connell Streets in the financial district. The building should provide its occupants with “the latest in workplace amenity and sustainability, an amalgam of the best in technology with the best of locations and the best of visions”, according to the client.

The 42,000-square metre building has been designed to achieve a world’s best practice 6-Star Green Star rating and a 5-Star Australian Building Greenhouse Rating (ABGR). The lack of perimeter columns will give the flexible floor plates of 1,600 square metres good access to natural light. Twin off-set cores, a full height atrium and ceilings measuring 2.85 metres enhance space and air flow. The elliptical design maximises coverage over the site and allows the orientation of the floor plate to the north towards the Harbour. The outer glass skin is separated by a large ventilated cavity from an inner double-glazed skin. This cavity contains adjustable and retractable automatic horizontal blinds that shade the internal skin and reduce solar heat gain while maintaining views. Recycled black water is used for bathroom flushing and recycled rain water for irrigation. A tri-generation system will use gas to generate energy for the building’s cooling, heating and electricity, and roof-mounted evacuated tube solar panels will produce heat for electricity. The full height atrium provides daylight and fresh air, and also allows for views throughout the building. Glass lifts are travelling through the atrium, a naturally ventilated space with little terraces for reception, break-out and meeting rooms. The Level 15 transfer floor has a heightened ceiling, winter garden and external terrace of 375 square metres. Level 28 has a roof top terrace of 700 square metres, which is shielded by the outer glass skin of the façade that rises 10 metres above the terrace floor.

A childcare centre, secure bicycle parking and shower/change facilities, a large forecourt and the entry hall, accessible to the public during working hours, are also part of the programme. The development is owned by DB RREEF. Completion is scheduled for early 2011. It is officially registered for Green Star–Office Design certification with the Green Building Council of Australia.

Ulf Meyer talks to Martin Reuter, the project architect to find out more about the office building.

UM: What is currently happening on the site?
MR: There are five smaller office buildings on the site that will all get knocked down completely. There is a 4- or 5-metre difference in level from Bligh Street to the other side. Our building will sit dominantly at the centre of a gate that the surrounding towers form. The view was the most important feature for our design; the view from the building was even more important than the view of the building.

Many neighbouring buildings use dark glass and have flush façades—they loosely follow the tradition of Ludwig Mies van der Rohe still. They act as if they are afraid of the light. In order to maintain the great views we quickly decided on an all-glass façade. In Australia’s climate you have to immediately think about a special technology for glass façades like that. Since we have a reputation for green buildings back home, we also wanted to use this as our strength and not just implant another American-style building. In the AGBR/Green Star rating we aimed for the very high 6-Star status.

UM: Did you have to convince the client?
MR: The great thing for us was that the client worked hand in hand with us. We did not have to start from scratch. The client had already understood that a green building is advantageous for him and his tenants because of the lower energy costs.

UM: The aim to have great panoramic glass façades and make the building green seems to be contradictory at first glance, no?
MR: That is why we have decided to give the building a double façade. Earlier architects have used brise-soleil elements to prevent their façades from overheating. An outer sun screen keeps the excessive heat out and can be protected by the outer façade. This was developed with our German engineering partners, but almost everything else was developed with Australian know-how. The collaboration so far was a wonderful experience.

UM: Can the inner windows be opened?
MR: Originally we wanted to offer that. This would be a first for Australia although we would have to wait and see if some tenants want to take that option or not.

UM: Does a double façade make sense without the advantages of openable windows inside?
MR: Yes, because it provides extra protection against noise and protects the sun screen from the wind. We also had to adjust our design to Australian habits in office layout. In Australia—like in most of the world—people are used to much deeper office floors than in Germany. Offices there are not usually subdivided into individual rooms. Our building is designed with one or two large clients in mind. So our floor plates were designed with a maximum flexibility in mind: Around the perimeter of the building, the floor could be broken down into individual office rooms.

We were successful in the architectural competition mainly for two reasons: efficiency and added value. We designed the first floor in the way the city likes it and our design for the upper floors was quite economical. Although some people think that round or elliptical floor plans are not all that efficient, we achieved a usable space of 93 percent. In our case the elliptical shape was the result, and not the beginning, of the design process. It has an atrium punched into it, the tallest atrium in all of Australia. It acts like the backbone and makes the input and throughput of fresh air possible at all times.

UM: Does 1 Bligh Street have underground parking at all?
MR: Yes, on four underground floors. But we also offer covered room for 300 bicycles. We do almost everything possible in green architecture today. We will have solar collectors for solar cooling through warm water on the roof and for electric power generation. We also have black water treatment. We originally wanted to use the water from the wash basins and rain water and recycle that as gray water. Now we will even clear the toilet water for the needs of the cooling towers, because there will be more gray water than needed for the watering of the plants. Australia can have severe water shortages, so it makes sense to seriously save it. We will even connect to the city’s waste water pipe and clear some of it for our cooling needs.

UM: So there will be a mini-cleaning system in your building?
MR: Yes, we could almost produce drinking water quality with it. Because of the enormous water needs for cooling in hot weather, it makes sense to use water with less than drinking water quality.

UM: So there will be two completely separate cycles ?
MR: Yes, there will be no distinction between gray and black water, just fresh and black. We also have a green wall adjacent to the neighbouring building that will be watered with our recycled water. The sky lobby will be used for the interchange between the two groups of elevators. There also will be a green sky garden that could be used as a social space or as a cafeteria.

UM: Will there be internal staircases for people who do not want to take the elevator for just one floor?
MR: That would be possible and will be built only according to the tenant’s needs.

UM: You also have to worry about the so-called primary energy consumption of your building. By using two aluminium façades, you are using a material that needs a lot of energy to be produced.
MR: That is right, but it can also be recycled over and over again. We could not use wooden façades in a high-rise building. For the inner façades wood would have been possible. The fireproofing would have been manageable.

Back to: In Conversation with Christoph Ingenhoven

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