The architecture of 41X

The architecture of 41X

By Josh McAlister

41X, the new home of the Australian Institute of Architects’ Melbourne-based teams, is a thin 21 level commercial office tower. The site is the Institute’s former residence on the corner of Flinders Lane and Exhibition Street. The journey to realisation for this project began in 2008 when the Institute conducted an Expression of Interest for a national design competition, which shortlisted four architectural practices, Ashton Raggatt McDougall, Design Inc., John Wardle Architects and Lyons Architects. The following commentary is gathered from an interview with the successful architects, Lyons, and discussions with co-directors of the project, Adrian Stanic and Carey Lyon.

The winning competition scheme was awarded in February 2009 with the Lyons entry judged as successful on overall design, sustainability, response to the city, commercial viability and the proposed image of the Institute capturing its past, present and future.  Stanic and Lyon suggest that the design intent of the competition design was maintained in the final building form.  As part of the competition entry, the four shortlisted entrants were commissioned to produce concept design drawings. Although the design was subject to significant detail resolution, the competition scheme bears considerable resemblance to what has been built.

The expression of the civic imagery for the Institute is key to the design concept of a public building within a commercial office tower. Lyons explored the idea of a hybrid public and commercial building by contrasting the permanence and weight of heavy stone like materials with corporate transparency. The form of the tower was developed as if sculpted from a stone block, avoiding atypical commercial disposition.

Revealing the Institute’s home to the city as a public space was a key feature of the Lyons competition entry. The Institute is located on the lower levels of the tower and has been designed to maximise public engagement.  Lyons’ conceptual idea of drawing the city street up into the building was achieved by locating a publically accessible stair at the perimeter of the building. The form of this monumental stair space was literally carved into the Flinders lane frontage visually connecting the Institute to the public realm, this then continues as additional internal circulation for the organisation.

The concept created a bespoke design for the Institute; they occupy the first five levels with access to the roof level on level 21. From the outset the Melbourne City Council (MCC) was supportive of having the Institute re-established in such a prominent city location. Although the site is located within a MCC height restriction zone where setbacks are required, Lyons argued no set back, instead proposing a reverse podium, cutting back the lower levels to widen the street. The effect of this strategy is the creation of a series of unique micro public spaces. The Institute (as developer) and the MCC saw this as an opportunity to give public space back to the streetscape, generally, something a commercial developer would not be inclined to do.

The original competition entry was for a 16 level building, being increased to 21 as the project evolved. The increase of five levels helped to make the project commercially viable. The site area is only 328m2 with the net sellable area being 275m2 per floor. To achieve efficiency on such a small floor plate the building core was continuously reworked to remove wasted space. Lyons examined the core in forensic detail with every 50 mm saving having a direct dollar value. One of the concessions made by the Melbourne City Council, that provided relief to the NLA, was a series of the bay windows that extend over the title boundary to the south facade. The bay windows allow views up and down Flinders Lane on all of the commercial levels, becoming the only building in the city to do so.

Lyons noted that the Institute was closely involved in the design process through project resulting in a significant partnership between the client, the architect and the contractor. The project was procured through a design and construct process with Lyons being novated to the successful bid team, Hickory Group.  Concerns regarding the loss of design intent were alleviated by achieving significant resolution of the design prior to novation. Lyons worked with the Institute to develop a tender package that was complete to Design Development level. As the developer, the Institute was able to insist that Lyons, as the designers, complete the documentation and construction phases  of the project.

The design and construct methodology enabled the Institute to de-risk the development process, as the delivery risk was passed directly to the contractor. Under this arrangement the Lyons and the design team worked directly with the contractor and sub-contractors to develop the various systems and related details, focusing on build-ability and quality to provide a positive outcome consistent with the design intent. On some occasions this process yielded results that exceeded the design intent, such as the original proposed concrete patterning on the north elevation, which was replaced with a high quality form liner solution for no additional cost.

The challenging feature ‘chiselled’ areas of the façade, were resolved through multiple workshops with the contractor and sub-contractors to ensure build-ability and quality. The contractor’s influence through the design and construct process was most evident in the alterations made to the design of concrete elements of the tower. Hickory Group initiated specific changes to the extent of precast to the exterior sun-shading fins and also the substitution of traditional concrete slab and band beam structure for an integrated BubbleDeck concrete floor system. This reduced the overall weight of the structure, reducing its material usage and increasing the structural efficiency of the building.

Now completed the occupancy of 41X is varied and diverse. These strata titled ownership arrangements are unique in the market offering single tenancy floors with three sided views of the city, making it one of Melbourne’s newest iconic boutique buildings. Overall this has proven to be a highly successful strategy for the Australian Institute of Architects.