"The design needed to resolve a number of conflicting requirements, including level changes between the two street entries," the architect says. "Easy access was critical, and there were differing tenant requirements for security control. We chose to extend the white limestone floor of the upper level, folding this down to create a dramatic staircase that is expressed as a major sculptural element in the foyer. The form of the stair extends upward to join with a curving, ribbon bulkhead that wraps over the entry doors at each end. The result is a sculpturally refined space that functionally supports both the office workers and the pedestrian traffic that frequents the through-site link."
The tower itself is a rich interplay of three architectural forms, including the sharp fin element that rises from the Liberty Place plaza to the roof. The framed volume on the primary elevation orients the tower to Sydney Harbour. This elevation is also defined by a curved rooftop feature with large Alucobond louvres that reflect different patterns of sunlight at different times of the day.
The glazing on another elevation has a stepped form that articulates the levels to which the lift banks rise there are fewer lifts to the upper levels, which consequently have greater floor areas.
Sustainability is another key feature of the project the tower is the largest building in New South Wales to achieve a 6 Star Green Office Design v2 rating from the Green Building Council of Australia. Even the heritage building benefits, says McPeake.
"Legion House receives little sun or wind making these unsuitable as renewable energy sources. Instead, the building receives its energy from a process called biomass gasification."
Legion House utilises the commercial paper waste generated from the ANZ tower. This is shredded and compressed to form paper briquettes, which are used in the gasification plant to produce Syngas.
"This is effectively a carbon-zero energy source as the greenhouse gases released in the energy production equal that absorbed in creating the biomass," the architect says.
Other sustainability measures at Liberty Place include two 450kW tri-generation plants that generate electricity, heating and cooling for the air conditioning, hot water systems and high-efficiency chillers. The building also has an active chilled-beam perimeter zone with low temperature VAV central zone, a high-performance thermally shielded glass exterior, rainwater harvesting, scheduled lighting to reduce power consumption, and external sun sensors and automated blinds for glare control. And to ensure a comfortable work environment, the introduction of outside air is 150% of the ventilation rate required by Australian standards.