Melbourne’s skyline is now a little greener with the completion of the world’s first fully-funded, competition-designed, retrofitted green roof.
Located atop 131 Queen Street, Melbourne, ‘Growing Up’ is an initiative of eight young business leaders taking part in the Committee for Melbourne’s Future Focus Group and demonstrates the environmental and social benefits of green roofs on city buildings.
A garden oasis within the city, ‘Growing Up’ has drawn upon considerable financial and in-kind industry support to become a best-practice example of how public and private organisations can partner with industry, business and research institutions to create innovative solutions to combat climate change.
Commitee for Melbourne
Merran Porjazoski (Project Architect)
Structural Engineer: Clive Steele Partners
Builder: Better Projects Australia
Growing Up Committee:
‘Growing Up’ explores the environmental, social and spatial potential of green roofs. The scheme includes a central landscaped hill, around which a singular circulation zone expands and contracts to create a number of gathering spaces of varying scales and orientations. Bound by edges of seating and planting, inhabitants are to be completely surrounded by greenery along a continuous experience of the roof. Traditional garden structures, such as a folly, gazebo and terracing, create diversity along the journey. The central hill provides the rooftop with an inward focus. It affords occupants the feeling of seclusion and protection when seated, without impeding views of the city and beyond when standing.
Located in the commercial/financial area of Melbourne’s CBD, the existing building at 131 Queen Street is programmatically diverse, with tenants including the Fo Guang Yuan Art Gallery and Temple, Open Universities Australia, and the Lyceum Language School. The configuration of the rooftop and central hill allows the building occupants to simultaneously enjoy the garden in a collection of small intimate gatherings, or for a single large function.
‘Growing Up’ is a place to escape to, a place of surprise, a place to meet, a place for quiet contemplation, a place to read a book, a place to hold a class, a place for BBQs, a place to exhibit, a place for meetings, a place to gain distance and reflect on life; an engaging and vibrant multipurpose outdoor living space activated by its inhabitants and contributing to the city, both socially and environmentally.
Green roofs provide significant environmental and social benefits to both the building upon which they sit and the broader environs.
Summer temperatures within the CBD are considerably higher than those in the surrounding natural landscape in a phenomenon known as the ‘urban heat island effect.’ Bare concrete rooftops, making up close to 20 percent of the total CBD land area, contribute greatly to this warming. Green roofs are widely acknowledged for assisting in cooling the urban environment through evaporation and the reduction of solar radiation.
Green roofs reduce storm water flows and naturally filter stormwater run-off, stripping water of its pollutants before it enters our natural waterways.
Green roofs add an insulative barrier to the top of a building, stabilising internal air temperatures and reducing energy consumption within. They increase biodiversity in the urban environment, and improve urban air quality.
Researchers from the University of Melbourne will monitor the environmental performance of ‘Growing Up’ to ensure that the environmental lessons learned will be available for the broader community to share. It is hoped that ‘Growing Up’ will capture the imagination of Melbournians, proving that nature can coexist with the built environment.
‘Growing Up’ is a practical example of the benefits of environmental sustainability and gives the owners, tenants and visitors to 131 Queen Street a whole new space in which to meet – an opportunity to get out of the grey, and onto the green.
A principle objective of ‘Growing Up’ was to demonstrate that the design challenges associated with retrofitting a green roof are not insurmountable and that the benefits that green roofs provide to the environment and building owners alike far outweigh the challenges associated with their construction.
‘Growing Up’ demonstrates the ease with which existing buildings can be retrofitted with a green roof without requiring modifications to the existing building structure. Accommodating the increased static weight associated with a green roof and distributing that weight in a way that will not compromise the existing building structure (which was not originally designed with a green roof in mind) was the largest challenge. The weight of soil, depth of garden beds, suitability of plants to the selected soil type and depths and even the weight of the plants themselves, needed to be carefully considered.
Construction was captured on time-delay camera to demonstrate the ease and speed of the construction process. With no lift access, building materials were craned onto the roof at the start of construction. The soil was blown up 12 stories from street level and therefore needed to be as lightweight as possible to facilitate this process.
‘Growing Up’ is home to over 1300 predominantly indigenous, drought-tolerant plants. The planting substrate has been formulated specifically for rooftop conditions, and the majority of plants have had proven success in such environs. University of Melbourne scientists assisted with the plant and soil selection based on their previous research into green roofs.
Further to the environmental benefits of the green roof itself (described above) selected building materials have a strong environmental imperative in themselves. They include recycled glass and recycled river pebbles for the permeable paving, recycled timber cladding for the planter beds, recycled expanded polystyrene formwork for the hill, and salvaged tiles for the seating.
Rainwater is collected from surrounding roof structures and gravity fed to water tanks at roof level. Permeable paving and drainage systems filter and reduce storm water flows into the broader storm water network.
‘Growing Up’ includes a dedicated research area for Melbourne University scientists to investigate plant species and substrates most suitable for Melbourne’s unique climate.
Sustainability is further enhanced by designing ‘Growing Up’ as a low-maintenance roof garden. Plants are largely indigenous and drought-tolerant, with only edible plants being occasionally watered by an irrigation system (fed by collected rainwater) in summer months.
The substrate used in planter beds has a longer life span than traditional organic potting mix. All garden beds are easily accessed for seasonal pruning and training of vines. The garden will create its own mulch from the aerated compost system on the rooftop. Off-cuts from succulents, grasses, herbs and fruit trees are deposited in the compost bin along with food waste from building inhabitants using the rooftop. This limits the amount of disposable garbage leaving the rooftop, and also creates a re-use within the garden for recycled waste. The aerated compost system prevents pests and bacteria in the compost.