Green spaces over the slab: Types, Initiatives, and Challenges for greener high-density environments


Green spaces over the slab: Types, Initiatives, and Challenges for greener high-density environments



Green spaces over the slab

Historically, the development of our cities has displaced nature, creating a clear division between urban and natural environments.

Green spaces over the slab

The design of green spaces within existing and new buildings has become critical to ensuring that cities evolve into more sustainable future-facing environments.

Historically, the development of our cities has displaced nature, creating a clear division between urban and natural environments. The more we understand the impacts of climate change, flooding, high temperatures, noise pollution, and the immense benefits of city green spaces for people’s and environmental health, the clearer it becomes that our cities need to be greener. The city’s liveability depends on it.

There are various ways of implementing green infrastructure within built sites as more substantial green spaces within high-rise buildings are slowly becoming part of the urban landscape. Green infrastructure includes the provision of green roofs, rooftop gardens, rooftop parks, rooftop community gardens, rooftop farms, and green walls.

The benefits of including these types of green infrastructure are well-known:

  • They provide recreation and relaxation amenities. Green roofs, for example, can provide space for commercial uses like bars, restaurants, or cafes.
  • They foster opportunities for social strengthening.
  • They absorb and retain rainwater and can be used to manage stormwater run-off in urban environments.
  • They clean the air and stormwater by filtering particulates and pollutants.
  • They reduce the energy budget of a building by improving thermal performance and reducing building heating and cooling requirements.
  • They reduce the urban heat island effect.
  • They create and preserve habitat and ecological biodiversity within highly urbanised areas.

Strategic support for the provision of vertical and rooftop greening in Victoria

In recent years, strategic documents, the planning scheme and local initiatives have seen increasing support for green infrastructure such as vertical and rooftop greening.

Plan Melbourne (2017-2050), a strategic document outlining the vision for Melbourne to 2050, identified making Melbourne a sustainable and resilient city as a desired outcome for the city’s future. Policy directions to achieve these outcomes include the direction to ‘make Melbourne cooler and greener’, with implementation actions seeking to provide guidelines for green infrastructure in developments. Such policy directions are quite significant as they provide a high-level framework for guiding future development.

Planning Schemes in Victoria have seen increased policy support for environmentally sustainable design (ESD) and green infrastructure. Planning Scheme Amendment VC216, gazetted in June 2022, saw changes to the Victorian Planning Scheme to better support environmentally sustainable development outcomes. Strategies and provisions were introduced into the Planning Scheme to variously address climate change considerations, including biodiversity in urban areas and support for urban greening. While these changes lacked specificity regarding the provision of vertical and rooftop greening, the now required consideration of climate change and ESD is certainly a recognised step forward towards a greener Melbourne.

At a local level, Councils are increasingly adopting a range of initiatives to improve ESD outcomes and support green infrastructure. Many Councils have now adopted the Sustainable Design Assessment in the Planning Process (SDAPP) program, which considers a development’s sustainable design outcomes at the planning application phase. Through SDAPP, all ‘medium’ sized developments require a Sustainable Design Assessment (SDA) report to be submitted as part of their planning application, and all ‘large’ sized developments require a Sustainable Management Plan (SMP).

Further, the City of Melbourne released Green our City Strategic Action Plan – Vertical and Rooftop Greening in Melbourne in 2017. The plan provides strategic direction and support for the provision of urban greening in Melbourne. Various Councils have also developed ‘toolkits’ or ‘guides’ on embedding vertical and rooftop greening in developments.

Given the existing strategic documents, the directions of the planning scheme encouraging environmentally sustainable development, and the emergence of local plans and policies encouraging environmentally sustainable initiatives, there is increasing policy support for the provision of green infrastructure in Victoria.

While strategic policy for the provision of vertical and rooftop greening encourages and supports the inclusion of such measures in developments, meaningful and specific policy remains scarce. However, the recent strategic policy direction and local government initiatives indicate a clear drive towards prioritising environmental sustainability in urban development, laying the groundwork for more comprehensive policies in the future.

Technical Challenges:

Rooftop Garden Technical Challenges

Some technical challenges for rooftop gardens are related to structural requirements and soil depth for implementing plantings and trees. Drainage, irrigation, and waterproofing are equally important to efficiently prevent water leakage and excess runoff in the building below.

Moreover, height challenges could be a concern for some rooftop gardens, as the plantings might be exposed to strong wind and different weather conditions, so careful consideration of specifying planting species to suitable locations is needed.

Although the construction of a green roof can be independent from the rest of a building project, early collaboration between specialists will help minimise design development risks and realise the full potential of rooftop gardens while ensuring safety, sustainability, and functionality.

The main technical challenges for community gardens relate to sunlight and soil conditions, which play crucial roles in farming and crop growth. The height of the farming-specific areas might present a challenge for people with disabilities, so their design should be universally accessible.

A good example of a rooftop community garden is the Melbourne Skyfarm in Docklands, a collaboration between Melbourne-based sustainability companies to transform a 2000-square metre rooftop car park into an urban farm and environmental oasis in the heart of the city. Located in Melbourne’s emerging Seafarer’s precinct, Melbourne Skyfarm directly overlooks the Yarra River and Melbourne Convention and Exhibition Centre.

The Commons, Brunswick, is an example from 2013 that brings environmental and social sustainability that maximised affordability and liveability for its residents.


Green Wall Technical Challenges

Vertical green walls that extend along tall buildings will depend heavily on maintenance after implementation, the system used for the green walls, and the weather conditions.

Generally, the location of all green walls should be accessible to the maintenance team either through the Building Maintenance Unit (BMU) system within the building itself or via a temporary platform at ground level.

The green wall system and the selected species would also affect the survival rate. An automatic dripped irrigation system will maintain sufficient moisture levels for the plantings and regular fertilising would be challenging due to its location, necessitating self-sustaining species.

Reach out to our landscape architecture team for enquiries about optimising vertical greenery for your new development at