While designing with nature in mind is not a new concept—architects and designers have been “bringing the outside in” for years now—few buildings have been inspired by, or been designed to reflect on, nature and other surroundings the way 111 Eagle Street in Brisbane, Australia has. The 52-story tower has 44 office levels with a total office space nett lettable area (NLA) of 63,385 square meters, two lobby levels, six car parking levels below ground, and a skin made of 30,000 square meters (323,000 square feet) of solar control glass. Those involved with the building design, Cox Rayner Architects and engineers at Arup, say it is the first high rise tower in the world to comprise what they call an organic vertical structure.
This structural design came about as many do; the architects had to work with the physical constraint of the build site. In the case of 111 Eagle Street, one of those constraints was an existing loading dock and ramp that serves neighboring towers on either side and which took up the middle half of the site, preventing columns from bearing down into that area.
To resolve that design challenge, Jayson Blight, senior design director at Cox Rayner Architects explained, his associates at Arup designed an algorithm for the structure that they describe as a ‘growing toward the light algorithm,’ with branch-like columns that reduce in thickness vertically.
“It gives the tower its unique architectural expression and is also a response to its context of large iconic fig trees in front of the site,” says Blight, who adds, “the organic structure was devised as a way of transferring loads gradually down through the height to land at ground points where footings could be located.”
Looking at the skin of the building, Blight says, “this is where the use of glass takes center stage”
“The decision to position the structure within a glass skin, rather than outside it, was made to respect the two Harry Seidler designed towers on either side, such that the glazing reflected these towers and the organic structure became a subtle, rather than overt, expression. It is at the base and the top that the structure bursts from the skin to reveal its full impact and relationship to the fig trees – the base being designed to allow the public to use the foyer as a connector between street and river,” Blight explains.
Energy efficiency was not sacrificed with the amount of glass that went into the project. The exterior glazing is ipasol neutral solar control glass from Interpane and the curtainwall was fabricated by Yuanda.
According to Interpane, the building has a glass façade with a solar factor of 27 percent that helps reduce the CO2 emissions but still allows all of the 3.1-meter (10 feet) high fully glazed floors plenty of light. In fact, 111 Eagle Street has received a six-star Green Star Award Design rating by the Green Building Council of Australia for its exceptional sustainability.
Nighttime, though, is when the sparks fly—or rather, the lights dance. The structure was designed to be distinctive and when darkness falls, it is made so by oscillating illumination.
“All columns are illuminated by LED lights that are computer-controlled to facilitate different intensities. One program is a gently pulsating phase called ‘Breathe,’ devised by the artist Alexander Lotersztain,” Blight said.
At the onset of the project, Blight and his team at Cox Rayner set out “to create a tower that would be both publicly recognized as belonging to the subtropics and recognized as site-specific, [an] aspect rarely if ever associated with the commercial office tower. That philosophy was achieved by utilizing the structural solution of the constraint to create an architecture that is responsive to the one significant natural landscape element remaining in the precinct from history, Brisbane’s cluster of iconic [area] fig trees.”
Specifically, he states, “Our aim was to push the boundaries of environmental performance for the office towers, catalyzed by the structural geometry which produced a minimum of material requirement.”