An apartment building opposite Sydney’s Hyde Park which won a prize for best apartment building in Australia used digital technology to mould the façade to changing conditions on the skin.

Eliza by Tony Owen Partners contains just 19 units, most being single floor apartments, but features a different profile for each level – a design strategy architect Tony Owen describes as “liquid architecture”. This variance in profiles is a response to the differing unit plans, views and sun access on each level.

The brief had asked for an exclusive apartment in the Sydney CBD that would also fit within the historic context of the area. Presenting a contemporary expression of the traditional principles embodied in neighbouring buildings, the 17 storey block combines classic 20th Century style with parametric design tools.

Key to its design is the fluid façades, which were designed entirely digitally, using scripting in Maya and Rhino software. According to Owen, this was essential because every floor had a different shape, and using the CAD-CAM technology allowed the team to send their files directly to the manufacturer for laser cutting in the factory.

Frank Gehry’s Digital Studio software also assisted in the fabrication geometry.

“In the past such a façade would have been cost prohibitive, but using this technology this complex solution becomes affordable and buildable,” says Owen.

The tower façade is clad in laser cut triangulated powder-coated steel panels, which are supported by an elaborate tubular steel structure. The podium incorporates the same geometry in sandstone, with the CAD files also sent directly to the stone supplier and the stone cut according to the architect’s files.

The design team says this is the first time such technology has been used in an integrated way in Sydney, although they did encounter some challenges along the way.

“We designed a façade which consisted of complex 3-way curves. We had to figure out how to build this using steel that could only bend in single curves,” Owen recalls.

“Another challenge was how to find efficiencies in a surface that changed on every level. In the end we were able to work the geometry such that there was a large degree of repetition in the façade.”

The architects also faced the problem of having to define and build such a complex surface in space.

“We used the Rhino model to define the geometry of the outer skin according to coordinates in space. The substructure, glazing, concrete and water proofing had to fit behind that. Over a 2 year period we were constantly returning to the 3-D model to check the construction details against that surface,” says Owen.

The tapering shape of the three storey penthouse, which maximises solar access and views to Hyde Park, terminates the fluid geometry.