A new online resource—the Growing Green Guide—is designed to help building owners, planners, designers, developers, renovators and homeowners include green plant roofs, walls and facades into their buildings to help manage the impact of a changing climate on city living.
Growing Green Guide: a guide to green roofs, walls and facades in Melbourne and Victoria, Australia, has been developed with advice from industry experts and knowledge from academic research, to explain how to create high quality green roofs, walls and facades.
Written for professionals who may be involved in the design, construction and maintenance of green roofs, walls and/or facades, the guide is also relevant to developers, homeowners, and local and state governments.
The guide was developed for the design, construction and maintenance of green roofs, walls and facades in Melbourne and Victoria. The project also explored policy options to support green roof, wall and façade development across Victoria, and identified possible demonstration sites for future development of green roofs, walls and facades in inner Melbourne.
Providing step-by-step advice and examples on how to incorporate green roofs, walls and facades suitable to Victorian conditions, the newly released guide is the result of a three-year collaborative project.
“The development of the guide was the culmination of a project supported by four inner Melbourne local governments through the Inner Melbourne Action Plan (the cities of Melbourne, Port Phillip, Yarra and Stonnington) and by the State Government of Victoria, through the Victorian Adaptation and Sustainability Partnership,” said co-author of the guide, John Rayner, who is a researcher in Urban Horticulture at the University of Melbourne, a project partner for the guide.
“We know now that green roofs, walls and facades provide multiple benefits for the environment and community, but having local guidelines on how to achieve these outcomes is a first in Australia.
“University research in green infrastructure over recent years has helped to define, shape and develop the guide, ensuring that it is current, relevant and applicable for projects in Victoria,” Mr Rayner said.
Stonnington City Councillor, Sam Hibbins said: “Stonnington has the second lowest amount of public open space at 6.7% (20sqm per person) of any Victorian municipality. We must therefore look for innovative solutions to create more open space and green our city. We can do this with green walls and roofs and strategic land purchases. The Growing Green Guide is a vital resource.”
Minister for Environment and Climate Change, Ryan Smith, said that the guide was made possible through $250,000 in funding from the Victorian Coalition Government’s Victorian Adaptation and Sustainability Partnership program.
“This is another great example of adaptation at a local level where local communities are empowered to take their own action to be more climate resilient,” Minister Smith said.
“It is gratifying to see councils, University of Melbourne and the local community joining forces to produce a valuable tool for urban landscapes.”
The guide offers innovative ideas for cooling buildings and the environment, while also increasing livability. It provides information on the design, construction and maintenance of green infrastructure, outlines the research undertaken and technical explanations, as well as providing a number of case studies and details on considerations required when incorporating vegetation on new or existing surfaces.
According to City of Port Phillip Mayor Amanda Stevens, the Growing Green Guide is a great example of how councils can collaborate to address sustainability issues and provide leadership, both to local government and industry.
“Port Phillip has a strong commitment to sustainable buildings, minimising water use and climate change adaptation,” Mayor Stevens said.
“The multiple benefits of green roofs, walls and facades allow buildings to be more resilient to hot weather, while minimising water use and energy use.”
Islands in the sun
The urban heat island (UHI) effect is well known and is a name given to a metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. The phenomenon was first investigated and described by Luke Howard in the 1800s, although he did not coin the term. The temperature difference usually is larger at night than during the day, and is most apparent when winds are weak. UHI is most noticeable during the summer and winter.
The main cause of the urban heat island effect is from the modification of land surfaces, which use materials that effectively store short-wave radiation. Waste heat generated by energy usage is a secondary contributor. As a population centre grows, it tends to expand its area and increase its average temperature.
Not all cities have a distinct urban heat island. Research has shown that mitigation of the urban heat island effect can be achieved through the use of green roofs and the use of lighter-coloured surfaces in urban areas, which reflect more sunlight and absorb less heat.
Commenting on the launch of the Green Growing Guide, City of Melbourne Environment Councillor, Arron Wood said: “Cities can be four to seven degrees hotter than surrounding suburbs due to the urban heat island effect. Green walls and rooftops help cool our city and retain stormwater, which helps reduce flash flooding.
“The guide will help transform existing buildings and create new ones, which can use their roofs, walls and facades to work with the environment rather than against it.
“The best minds have been brought together to develop a guide that will help transform existing buildings and create new ones, which can use their roofs, walls and facades to work with the environment rather than against it,” Cr Wood said.
“We estimate that right now there are around 50 green walls, 100 green roofs and many green facades across Melbourne. Our vision is that these numbers will multiply with the release of this comprehensive guide.”
The Growing Green Guide has been funded through the Victorian Government’s Sustainability Fund under the Victorian Adaptation and Sustainability Partnership through the Inner Melbourne Action Plan councils.
Currently, the Growing Green Guide is being brought to life through an innovative display of a shipping container, covered with green roofs, walls and facades. It was installed at City Square in mid-March this year, in the lead-up to the Melbourne International Flower and Garden Show, Australia’s biggest flower and garden show where growers, florists, designers and students gather along with the best blooms and foliage that the floriculture industry has to offer.
The idea behind the Growing Green Guide display is to showcase the beauty and functionality of these new technologies.
The guide is targeted at projects based in Melbourne and Victoria, Australia, but is also largely relevant for a wider geographic area.
Fifty shades of green: urban food production
The Growing Green Guide points out that just as walls and roofs of buildings provide a surface for greening in dense urban areas with very little ground-level space, they also represent a possible location for urban food production.
In some parts of the world large areas of rooftops in inner urban areas are being transformed into urban farms. More commonly, roofs are used to house hydroponic or container-based plots for food production, such as the Pop Up Patch at Federation Square, Melbourne.
Walls have only been experimented with on a small scale. Facades tend to lend themselves to the production of food from climbing plants such as beans or passionfruit.
As the issue of adequate plant nutrition is so crucial to food production, it is uncommon to see examples where urban agriculture is practised on roofs where the layers are loose-laid, rather than in containers. Where containers are used it is possible to remove all the growing substrate and replace completely. In fact, there are some urban agriculture rooftops where the food is grown on hydroponic systems on the roof to avoid the need for a growing substrate altogether.
Role of hydroponics
Hydroponic green wall systems consist of two general types—modular, which can be hydroponic or substrate-based, and felt covered hydroponic panels.
The systems are installed via brackets that sit out from the load-bearing wall (or a stand-alone structure) to create an air gap between the wall (or other structure) and the backing sheet of the green wall system. In a hydroponic system, an inert growing medium is provided to which the plants physically anchor, such as a horticultural foam, a mineral fibre or a felt mat. These materials can act as a water retentive sponge, although the more they soak up the heavier the system becomes.
The authors say that one of the advantages of using a hydroponic system is that there is “no structural decay of the growing medium, no salt build-up from fertilisers, and nutrients are supplied in a precise and controlled manner. Over time, plant roots grow and ramify through the entire system to create a very robust network.”
“In hydroponic systems, plant nutrition is delivered by a fertiliser injection system that releases controlled doses of fertiliser into the irrigation system,” Mr Rayner said.
“Management of fertigation systems and rates of delivery requires specialist knowledge, as it is more complex than fertilising soil or growing media. Hydroponic systems require continual monitoring of pH, water hardness and total dissolved solids (TDS), and adjustment of these parameters where necessary.
“For hydroponic green wall systems, the fertigation system may apply 0.5-20 litres of irrigation solution per square metre per day. Internal green wall requirements are at the lower end of this range, and external green walls at the higher end,” he said.
“Irrigation cycles typically last a few minutes and will be required several times a day. Keeping irrigation volumes low minimises waste and reduces run-off. Irrigation run-off may be captured in a tank at the base of the wall and recycled back through the green wall system.”
Investing in the future
The foreword to the Growing Green Guide is written by Sidonie Carpenter who, in 2007, co-founded Green Roofs Australasia, the peak body for the green roof, wall and facade industry. She was president of the association for almost four years and is currently the board member for Queensland. Sidonie has a landscape architecture practice in Brisbane.
Ms Carpenter points out that the guide is only one of three main outputs developed by the Growing Green Guide project team—a policy options paper and feasibility study and design for four demonstration sites have also been completed.
She praises the development of the guide being an initiative that will strengthen the industry as a roadmap for urban landscaping.
“Building one green roof will provide benefits for a small number of people and the local environment, but developing this Growing Green Guide provides the knowledge and confidence to implement innovative and good quality green roofs and walls for years to come. It is what the green roof and wall industry needs in able to plan, design and maintain quality green roof and wall systems throughout Australia,” Ms Carpenter said.
“Cities around the world have found green roof support and development has strengthened following the publication of how-to guides like this.
“Given the predicted impact that climate change and population growth will have on our urban environment, can we afford not to invest in these types of sustainable solutions? Green roofs and walls provide a wide range of environmental, economic and social benefits, both public and private. They can reduce urban heat loadings and stormwater run-off, increase the energy efficiency and liveability of buildings, provide a range of habitat outcomes and even produce food,” she said.
“These guidelines will help to develop an understanding of the technology and build knowledge about the benefits and methods of green roof/wall/facade design, construction and maintenance for all sectors of the industry.”
The guidelines have been written for Melbourne and Victoria, but much of this information has national and international relevance. The Growing Green Guide team has issued an open invitation to others to use the guidelines’ contents to develop additional resources, or even produce a second version through their Creative Commons licensing.
The Growing Green Guide can be downloaded at: www.growinggreenguide.org
About the author
Christine Brown-Paul is a Sydney-based journalist and a regular contributor to PH&G, with a special interest in the environment and sustainable technology. Email: firstname.lastname@example.org