Centrelink National Headquarters
The plan form comprises two major volumes separated by an atrium (main street) which provides a high level of social and environmental amenity. The width of the floor plates is designed to maximise daylight penetration from external windows and the atrium.
The floor plates accommodate office areas, while the atrium is activated by breakout spaces, meeting rooms and cafes. Orientation is directly north south with the louvre-protected atrium facing north to maximise daylight penetration. Landscaping of the site with local species promotes biodiversity.
One of the key brief requirements was a flexible floor plate and building services design to accommodate Centrelink’s high churn level of 110 per cent annually. Overnight (4pm to 7am) re-configuration of large office areas (1000 sq m or more) is achieved by a flexible service grid, modular workstations and access flooring to the major floor plates.
A 250 millimetre -deep ceiling service zone accommodates supplementary mechanical equipment, fire sprinklers with flexible heads, and light fittings with flexible leads enabling repositioning of services without modification to supply lines.
As a Commonwealth Government facility, the building targeted and achieved a 4.5 star AGBR. The design of the building envelope was critical to achieving this performance, in addition to addressing related sustainability issues of longevity, minimal maintenance and resource efficiency.
Precast concrete structural panels, shaded double-glazed (low-E) windows to the north, east and west elevations and insulated cladding panels are the major wall elements.
Thermal performance is achieved via air spaces, bulk insulation and, where overall wall thickness was reduced, specialised double-sided insulation material. Floor slabs are insulated for two metres inside the external walls to minimise thermal bridging.
Selection of building finishes has contributed to a high level of internal environmental quality. Low VOC Onterra carpet tiles are used throughout, which facilitate re-use and local replacement. Timber veneers from sustainable sources are used in the breakout areas to humanise the informal socialisation zones.
Building system design and management contributes to the AGBR. Low temperature VAV airconditioning to the main office area is supplemented by high-level chilled ceiling panels, low-level heated slabs, and displacement systems, which maintain conditions within the design range in the non-conditioned atrium space. Hot water is provided by roof mounted gas-boosted solar water heaters.
General lighting to supplement daylight is provided by T5 fluorescent fittings (dimmable) controlled by proximity switching devices (photoelectric cells and motion detectors). External fire stairs are largely day lit. Total building energy consumption is managed by a sophisticated BMS, which alerts facilities personnel by alarm when consumption exceeds design levels.
All greywater (kitchen, handbasins, showers) is collected, treated and reused for toilet flushing. Roof water is collected and used to supplement the grey water system, the remainder detained onsite before release ultimately into the Murrumbidgee River system. Carpark runoff is collected in landscaped deep swales which filter out pollutants before detention and release into the river system.
All sanitary fixtures and tapware are water efficient. “Greenway” has delivered a number of key ESD objectives – low environmental impact at both global and local scale, high occupant amenity and substantially reduced wastage usually associated with high churn. The building captures the synergistic benefits of environmental, social and economic sustainability, the new paradigm in workplace design.