Reclaiming the Roofscape - a natural solution

The Royal Melbourne Institute of Technology (RMIT) at its City Campus, is reclaiming one of its rooftop spaces to create a roofscape which is guided by principles of ecological sustainability. The project is a joint administration and student initiative which has grown out of a desire by users of the roofspace to enhance the educational, amenity and ecological value of the university campus by provision of a nature experience in a highly urbanised space - the Melbourne CBD.
The broad aims of the project are to foster a sense of investment in the campus, add to the biodiversity of the region, use otherwise under-utilised space and to provide a model of sustainability that has educational value. Campus stewardship initiatives such as this can provide an important training ground for students to become advocates for environmental responsibility in their vocational fields and more generally engender a broader sense of civil responsibility.
The project will integrate academic involvement through curricular activities in a range of diverse disciplines including environmental science, visual communications and mechanical engineering. The students and other users of the roofscape have been and will continue to be actively involved in all stages and aspects of the roofscape development concept, design, implementation and management.
The roofspace covers approximately 1500m² on the fourth floor of two buildings constructed in 1937 and 1942 and is bordered by a waist high parapet. (See left). The buildings are predominantly sited on the corner of Franklin St and Bowen St within the City Campus. Of the roof space, about 900m² is currently occupied by temporary buildings housing office, academic and student space and includes a Muslim prayer room. Long term plans seek to relocate many of these buildings which will allow further development of the roofspace. The remaining 600m² is located predominantly on the 1937 building on Bowen St and it is this area which is subject to the initial phase of the development.
The main features of the roofscape include: * flowering indigenous planting * alternative power to run irrigation and lighting * a board walk through the grassland * planters for trees and climbers * Koori food and implement plants * interpretative signage * a glasshouse for propagation * furniture * open space events * spaces for art installations
The flowering indigenous grassland planting, creating an inherently Australian sense of place, is the principle vegetation component of the landscape. This planting will cover approximately 80m², will be grown in a shallow profile of 200mm depth and will place minimum weight in the roofspace. (Engineering assessments of the buildings have identified the structural capacity showing several zones with a range of weight bearing capacities.)
The grassland will provide an indigenous community which will be ecologically based, subject to successional processes, require minimal inputs in respect to nutrients, water and labour resources compared to traditional plantings. The style of planting will provide users of the landscape with a functioning plant community which brings the natural cycles of nature into the urban landscape and provides habitat for local fauna. The grassland will function in an interpretative role for the original flora of the Melbourne area, will conserve genetic resources and will perform soundly in biological terms in the rooftop environment.
Containers with attached frames planted with climbers will provide screening for discreet areas such as the Muslim prayer room and along the parapets, linking visually with the streetscape. Large planters will support tree planting of Sheoke. Species selection has in part been driven by the need to utilise species which will grow in the exposed conditions of the rooftop.
One of the keys to utilising shallow profile plantings is effective supply of water. The irrigation system has been designed to minimise water usage by using moisture sensors which will determine the volume of water applied and prevent over-usage. The system will be further developed to utilise water captured from surface runoff and recycled via power generated by alternative technologies.
Various components of the landscape have been chosen because of their adherence to sustainability principles and for appropriateness to the site. The medium chosen is Debco Landscaper Mix, a light weight medium which is primarily composed of by-products from mining and forestry industries. The base mix is composed of 60% composted pine bark, 30% basalt dust and 10% brown coal fines.
Nutrient levels post establishment will be monitored through academic projects and maintained at low levels. This will decrease the potential for rank growth of competitive species in the grasslands site and maintain space for the inter-tussock flowering native forbs. The low growth rates will decrease maintenance requirements and favour persistence of indigenous species. Medium and fertility levels will be maintained through incorporation of composted material and output from worm farms.
Management of the site will be undertaken in part by a “Friends of the Roofscape Group”.
In the urban centres of Australia, rooftops are a significant untapped resource. RMIT has recognised that the development of rooftops into places that provide a nature experience in often hard, hostile, alien environments can enhance human well-being, build a sense of community and a relationship with nature and provide models of sustainable living practices in urban spaces.