RMIT University Building 21 Green Facade
Location: RMIT University, 124 Latrobe Street, Melbourne, Victoria
Completion Date: 2011
Area: 122 m2 on an existing building
The green facade was constructed on the north and west-facing external walls of Building 21, a 60-year-old brick building. Planter boxes at the base of the facade support plants that climb up a trellis stretching the height of the wall. The wall can be viewed by the general public and is mostly seen by RMIT students and staff.
The RMIT University city campus in Melbourne is a publicly accessible space made up of historical and modern buildings, interspersed with functional open areas. With the completion of University Lawn Precinct and the refurbishment of all of the surrounding buildings, Building 21 needed a facelift as the last piece in the precinct. A green facade was constructed on the rear of the building.
The Building 21 green facade was a joint project between RMIT University, Peter Elliot Architecture and Urban Design, engineers BHS Consultants, landscape architects Rush Wright Associates and TJS Services. The specific facade structure was provided by Ronstan Tensile Architecture.
Design and components
The facade includes the following elements:
- aRonstan X-TEND® mesh trellis system in a diamond-shaped pattern. The trellis system is secured in place by steel framing at the top, bottom and sides of the wall. There is a 40 cm gap between the trellis system and the brick facade of the building so no root barrier or waterproofing layers were needed
- planter boxes, which are mounted to the existing brick facade using a galvanised steel frame which encases the entire planter box. Zinc sheet vertical cladding covers the front of the boxes and extends down to hide the drainage system below.
The sides and base of each planter box are lined with Atlantis® 30 mm Flo-Cell™ drainage cell and slotted Agridrain Pipe, and then covered with 2 mm geotextile Bidim® A14G membrane. The bases are lined with a 40 mm sheet of Hyrdocell hydro foam.
A drip irrigation system is used, with a slotted drainage pipe running along inside the base of the planter boxes to provide drainage.
Hydrocell 40 extensive media, a lightweight soil mix, was chosen to reduce stress on the existing brick wall. The substrate was topped with a 45 mm thick stone mulch layer to provide protection from the elements.
Forty-nine individual 140 mm plants, Kennedia rubicunda (Dusky Coral Pea), were installed in the planter boxes. Temporary bamboo supports were used to help the plants grow up and onto the trellis. Plastic clips were used at intervals of 40 cm to secure the climber to the trellis. Provided by Ronstan, the clips are designed to allow for the plants’ growth.
The design of the green facade included maintenance requirements. The site can be accessed with an elevated work platform. The planter boxes are raised above pedestrian level, but are low enough to be accessed using a ladder.
The green facade requires a moderate level of maintenance, contracted to the university’s general landscaping contractor. Regular maintenance tasks include:
- monthly inspection of irrigation system function
- twice yearly (spring and autumn) pruning and retraining climbers around windows
- twice yearly (spring and autumn) fertilisation, plus additional if required
- monthly comprehensive visual inspection
- weekly general inspections (including removal of rubbish)
Total: $230,000 (excluding ongoing maintenance).
Specific costs of project components:
- Planter boxes $80,000
- Plants and substrate $25,000
- Plumbing and irrigation $25,000
- Trellis system $90,000
- Hire of access equipment $10,000
- Ongoing maintenance contract N/A – part of general RMIT landscape
- Results and reflections
The architect believes that the building now sits comfortably as a backdrop to the University Lawn Precinct, with the creeper-covered walls meshing into the urban landscape. He notes the appearance of the building has been successfully transformed through the softening effect of the creeper-covered wall. Initial plant growth has exceeded expectations but will need to be monitored to be maintained into the future.
The ongoing level of required maintenance can be carried out as part of general RMIT landscaping. RMIT reports that no plants have been removed or replaced to date, due to adequate facade coverage.