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Architectus
Qantas Headquarters

Adaptive reuse achieves environmental benefits

Adaptive reuse: when three becomes one

In early 2010, Qantas Airways Limited held a design competition for the redevelopment of their existing headquarters buildings as part of a consolidation of their Mascot accommodation into a single campus environment. Their existing facilities comprised three speculatively developed 1980s office buildings linked by a common basement car park. The winning scheme designed by Architectus recognised that Qantas had a community but no public space in which it could connect and grow and proposed a cost-effective, functional and inspiring solution linking all three buildings with an atrium structure comprising two main spaces; the ‘internal street’ and the ‘entry hall’. The Qantas Headquarters redevelopment has not only seen an increase to the NABERS rating from 1.5 to an estimated 5 stars, it has provided a new connected environment for the people that work there along with a platform for interaction and communication.

Adaptive reuse - Qantas Headquarters

Figure 1: Longitudinal section

The ‘internal street’ is a four-storey volume between buildings A, B and C, conceived as an outdoor space indoors, is enclosed by a generously glazed roof and fully glazed facades. At ground level it is activated by food and beverage retail outlets with sliding and/or bi-fold doors and meeting room spill-out spaces.

The largely opaque existing facade to upper levels has been removed and replaced by floor-to-ceiling glazing with selected areas of floor-plate extended into the space to create balconies and office pods. These interventions with a bridge and two staircases linking all levels within the street provide improved physical and visual connections encouraging interaction and engagement between work spaces. A courtyard to the north extends the stone floored, tree-lined streetscape externally creating a barbeque and sheltered outdoor breakout space. The ‘street’ is the focal point of the campus providing valuable, engaging and comfortable communal space to increase staff communication and enhance the working environment with better amenity and aesthetics.

Figure 2: ‘Internal street’

Adaptive reuse - Qantas Headquarters

The ‘internal street’ is classified as a ‘non-conditioned space’, BCA Section J restrictions on roof light glazing are not applicable. CFD modelling was utilised to optimise the extent and selection of roof and facade glazing. Generous glazing allows for excellent daylight penetration into the space and adjacent office environment and allows for the introduction of trees. The partially-conditioned space mediates between the internal office and external environment.

Displacement ventilation at street level, including spill-air fed from all office floors, creates a stratified interior environment to keep conditioned air where it is most required, with mixed-mode ventilation and high-level exhaust fans operating at appropriate times to facilitate a comfortable but energy efficient outcome. Where an increased level of environmental control and performance is required, internal functions are locally conditioned and protected by automatic blinds, such as at reception.

Figure 3: Connectivity is achieved through a bridge and two staircases.

Adaptive reuse - Qantas Headquarters

The ‘entry hall’ comprises a triple-height volume with a large glazed facade addressing Bourke Road and the campus vehicular drop-off point.  It provides a single, consolidated entry and a unifying and brand enhancing front-of-house experience for staff and visitors, consistent with that of other landmark Qantas destinations. Its scale is appropriate to the size of the overall office accommodation and commensurate with an airline of Qantas’ stature. The dynamic form of the new entry facade and over-sailing roof are realised in a restrained material palette.

Adaptive reuse - Qantas Headquarters
Adaptive reuse - Qantas Headquarters

Figure 4: The tapering plan form of the entry hall draws people up the stairs and escalators to the ‘street’.

Sustainability initiatives:

  • Adaptive reuse: retention and re-use of existing office buildings/structures.
  • Energy efficient atrium design: non-conditioned atrium space which utilises background conditioning (not exceeding 15W/m2) and spill-air drawn from all adjacent office floor plates to provide a mediated internal environment at least -5OC colder than the external environment in summer and +5OC warmer than the exterior in winter.
  • Mixed-mode ventilation: the conditioning detailed above is replaced/supplemented by natural ventilation from large banks of louvres and running the roof mounted smoke exhaust fans in background mode at appropriate times.
  • Internal greening: internal trees within the streetscape.
  • Rainwater harvesting: rainwater collected from the atrium roof is used for toilet flushing and irrigation.
  • Tri-generation: electricity, cooling and heated water is supplied from an adjacent tri-generation plant.

Figure 5: An existing external balcony to building C is retained linking to the ‘internal street’ and providing access to a new 210 seat auditorium. The form of the auditorium acts as a hinge to resolve the confluence of several non-intersecting grids at the meeting point of the ‘street’ and ‘entry hall’.

Adaptive reuse - Qantas Headquarters

Figure 6: Model illustrating the new facade and internal street connecting the three existing buildings.

Adaptive reuse - Qantas Headquarters