As landscape architects for the Victorian Desalination Project, ASPECT Studios have orchestrated the inclusion of an extensive green roof on the primary buildings of the process plant.

The green roof, meeting visual amenity performance requirements through the minimised use of reflective materials, is the dominant visual element in the coastal landscape setting. Yet, it remains integrated with the architectural components of the site.

A key challenge faced by the architects was the absence of a relevant green roof design standard or an established green roof industry in Australia. This meant that there were no strict precedents they could adhere to when designing the green roof.

The resulting innovative design strategy took into account the building roof pitches, loading constraints, and the use of local indigenous plants. Sustainable features, such as the planting media or substrate being designed with a high water holding capacity, air-filled porosity, saturated hydraulic conductivity, and good particle size distribution, was furthermore enforced.

ASPECT Studios believe that the Victorian Desalination Project’s green roof could spark a surge in the uptake of green roofs in Australia once other architects realise the possibilities these projects offer. If this occurs, there would be an increase in biodiversity values, reduction in storm water run-off volumes, acoustic attenuation, and a potential seed bank of local provenance genetically pure plant species for future ecological restoration.

Ultimately, the green roof represents the potential that Green Infrastructure, specifically Living Architecture, has in realising energy reduction through increased thermal performance, mitigation of the Urban Heat Island Effect, and carbon sequestration and reduction in carbon concentrations.

INITIATIVES

  • Development of a light weight substrate with high water holding capacity and air filled porosity able to support plant growth
  • Utilisation of 26 species of locally occurring coastal plants, many of which are used for the first time on an extensive green roof in southern Australia. The plant species have traits that are tolerant of the conditions on the green roof
  • Biodiversity enhancement through use of local provenance species, with seeds collected from within 40km of the site
  • The planting design of the green roof is configured to maximise self-regeneration of plant species
  • Utilisation of locally sourced aggregate and organic content of the growing media composition
  • Integration of the water proofing strategy with the green roof
  • Low water demand planting design
  • Highly efficient irrigation system, with modelling of irrigation water demand based on historic and predicted rainfall data. The irrigation strategy of the green roof draws from site-captured water stored in a purpose built irrigation storage pond. The irrigation water storage volume is based on water demand simulation for available roof catchment areas
  • Design against wind action
  •  The green roof also showcases principles of Water Sensitive Urban Design (WSUD), which allows it to cope with the hot-dry conditions of the southern Australian summers
  • Various parts of the overall growing profile utilise recycled products, such as the growing media where recycled timber chips are incorporated as a light weight alternative to straight soil, along with recycled geo-textile materials

Images: Thiess-Degremont Joint Venture and Fytogreen