Victoria’s guide to green roofs, walls and facades
Growing Green Guide for Melbourne
Version 2.8
22nd October 2013
For citation purposes: Department of Environment and Primary Industries, 2014, Victoria’s Guide to Green Roofs, Walls and Facades, State of Victoria.
Disclaimer
The information published in this guide is provided by the Growing Green Guide partners to disseminate information in regards to the design, construction and maintenance of green roofs, walls and facades. It is not and does not purport to be a complete guide and is not a substitute for professional advice.
This publication may be of assistance to you but the Growing Green Guide project partners (City of Melbourne, City of Stonnington, City of Yarra, City of Port Phillip, The University of Melbourne and the State of Victoria) and their employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
Reference to any organisation in this booklet is not to be construed as an endorsement or recommendation of any information, goods or services supplied by that organisation.
The Growing Green Guide partners accept no responsibility to you or anyone else arising from any act or omission of any third party referred to in this booklet or any loss, including damage or injury when using and/or obtaining information, goods or services.
The information contained in this guide is based on information available at the time of writing. It is liable to change and we do not and cannot guarantee its currency.
The project partners reserve the right to make changes to the Guide at any time.
Preface
This guide has come about from the commitment of a great number of people who are already involved in designing, constructing, maintaining and researching green roofs, walls and facades. The development of guidelines has been supported by four inner Melbourne local governments, - the Cities of Melbourne, Port Phillip, Yarra and Stonnington, the University of Melbourne and the State Government – through the Victorian Adaptation and Sustainability Partnership.
This Guide is written for a wide range of green roof, wall and facade professionals from those involved in planning and design through to construction and ongoing maintenance. The Guide is also relevant to developers considering green infrastructure options, homeowners interested in building their own green roof, wall or facade, government staff and anyone else wishing to learn more about the implementation and management of these systems.
It is written primarily for projects based in Victoria, Australia, but is also largely relevant for a wider geographic area.
Section 1of the Guide explains what green roofs, walls and facades are, why they are important particularly for urban areas and outlines the potential benefits of these systems in Melbourne.
Section 2 of the Guide introduces some of the research that has been undertaken on green roofs, walls and facades and will be of interest to those wanting a more in depth understanding of the potential impact of these systems.
Section 3 provides a technical explanation of the design, construction and maintenance of green roofs, walls and facades and was written in collaboration with industry experts. It provides an overview of the considerations required by anyone interested in incorporating vegetation onto either new or existing building surfaces.
Section 4 highlights examples of existing green roofs, walls and facades in Victoria. Each case study provides a detailed description of the project’s purpose, cost, components used, lessons learned and advice from the project team.
This Guide has been put together, with up-to-date advice from industry experts and knowledge from academic research, to help everyone understand how green roofs, walls and facades can help change the face of our urban environments into the future.
This guide has been developed under a creative commons licence. It is expected and encouraged that these guidelines are periodically updated and used by others to keep this information accurate and current.
Foreword
To be added in final version
Table of Contents
Victoria’s guide to green roofs, walls and facades
Disclaimer
Preface
Foreword
Section One: An introduction to green roofs, walls and facades
1.1 Background
1.2 Definitions
1.3 Benefits of green roofs, walls and facades
Next steps
1.4 Frequently asked questions
Section 2: Evidence for the benefits of green roofs, walls and facades
Contribution to urban cooling
Reducing the energy budget of a building
Managing stormwater volume
Improving stormwater quality
Urban air quality
Human health and well being
Section 3: Technical Guide
1. Introduction
2. Site analysis
3. Planning and design
4. Building and Installation - general advice
4.1 Sourcing skills, expertise and information
4.2 Occupational Health and Safety considerations
4.3 Insurance and system warranties
4.4 Project completion
5. Building and Installation - Green Roofs
5.1 Roof decks
5.2 Waterproofing
5.3 Protection layers
5.4 Drainage layer
5.5 Filter sheet
5.6 Growing substrate
5.7 Vegetation
5.8 Leak detection
5.9 Thermal insulation
5.10 Irrigation
5.11 Wind considerations
5.12 Slopes and shear protection
5.13 Hard landscape elements
6. Building and Installation - Green Walls
6.1 Structures and components for green wall systems
6.2 Waterproofing
6.3 Irrigation and plant nutrition
6.4 Vegetation
6.5 Lighting
7. Building and Installation - Green Facades
7.1 Wall protection and different façade treatments
7.2 Soils and growing substrates
7.3 Drainage and irrigation
7.5 Vegetation
8. Maintenance
8.1 Maintenance planning
8.2 Maintenance checklists
8.3 Plant nutrition
Section 4: Victorian Case Studies
1.1 The Venny Green Roof
1.2 Triptych Green Wall
1.3 RMIT Building 21 façade case study
1.4 Freshwater Place Green Roof Case Study
Glossary
References and source material
Text sources
Standards
Web based and company sources
Acknowledgements
Appendices 2
Section One: An introduction to green roofs, walls and facades
1.1 Background
Green roofs, walls and facades are used worldwide to manage climate impacts in urbanised areas. Australians are beginning to realise the potential of these installations to increase the resilience of our cities to the impacts of increased temperatures, intense rainfall, habitat loss and increased energy use.
Like many other cities in the world, Victoria’s capital city Melbourne is facing pressure from increasing urbanisation of the landscape. Rapid population growth and urban development has transformed what were natural environments to engineered infrastructure. This, accompanied with greater heat generation from machinery, and the absorption and retention of the sun’s heat on building and road surfaces, creates an unnaturally warm environment in our cities, a process known as the Urban Heat Island Effect.
The transition from natural landscapes to hard infrastructure has also resulted in the loss of vegetation and habitat, more flash flooding, and negative effects on human health and well-being. Many of these issues are exacerbated with the increasingly variable weather patterns that climate change is bringing. These pressures present enormous environmental and social challenges and require new ways of thinking to make our cities more liveable now, and into the future.
Cities around the world have recognised the importance of green infrastructure; that is, the incorporation of vegetation into urban structure and function. This can alleviate the pressure on the natural systems that support city inhabitants. Green infrastructure includes trees, parks, water sensitive urban design (such as wetlands and vegetated river banks), and green roofs, walls and facades.
As our cities move towards high density living, there is proportionally less green space at ground level per person. Green space is recognised as being beneficial to human health and wellbeing and provides a respite from the stresses of urban living. Green roofs can create community places where people can garden, visit, play and relax together and can compensate for the loss of local greenery. Green walls and facades provide impressive aesthetic outcomes and can also significantly improve local microclimates.
Australia is beginning to realise the potential of green roofs, walls and facades to assist in reducing the impacts of increased temperatures, intense rainfall, habitat loss and increased energy use in cities. In 2011 there were an estimated 87 green roofs in Victoria and the number is rising. In 2013, it was estimated that Melbourne has at least 50 green wall installations. There are untold numbers of green facades throughout the city and suburbs.
We already know that green roofs, walls and facades are feasible in Melbourne and in other parts of Victoria, and that if they are well designed, constructed and maintained they can help us live more sustainably. This Guide provides useful information on how green roofs, walls and facades can help cities adapt to climate change impacts and make Melbourne, and other urban centres in Victoria, more liveable in the future.
1.2 Definitions
1.2.1Green roofs
A green roof is a vegetated landscape built up from a series of layers that are installed on the roof surface as ‘loose laid’ sheets or modular blocks.
Green roofs are constructed for a number of reasons - as a space for people to visit, as an architectural feature, to add value to the property or to achieve particular environmental benefits (e.g. stormwater management, biodiversity, thermal insulation).
Vegetation on green roofs is planted in a growing substrate (a specially designed soil-like medium) that may range from 50mm to over a metre in depth, depending on the weight capacity of the building’s roof and the aims of the design. Green roofs will do best if they have some capacity for irrigation, although it is possible to create a green roof that survives without any irrigation (but be aware that there will be periods of die back).
Green roofs have traditionally been categorised as extensive or intensive. Extensive green roofs are lightweight with a layer of growing substrate that is usually less than 200mm deep. Extensive green roofs generally have lower water requirements and grow smaller sized plants. Intensive green roofs are generally heavier, with a deeper layer of growing substrate that can support a wider variety of plants. Because of this they can have greater needs for irrigation and maintenance, compared to extensive roofs. Traditionally extensive green roofs were seen as light weight, non-publicly accessible, spaces whilst intensive green roofs were designed as amenity spaces for people. Over time the boundaries between these types of roofs have blurred, and terms like semi-intensive or semi-extensive have been introduced to describe roofs that are a blend of both categories. These categories are used by the International Green Roofs Association, however this guide avoids over categorisation of roof types and instead describes particular characteristics, such as depth of growing substrate, as needed.
Other descriptions of green roofs include Brown roof or Ecoroof, which are generally lightweight, with shallow, substrate and minimal access and maintenance. They are typically associated with low growing plants - generally succulents. Biodiversity roofs are typically lightweight, with a focus on using native vegetation and may be designed for a particular species of invertebrate, bird, mammal, or plant. Roof gardens orPodium roofsare heavier with deep substrate, designed for access by people. They usually require regular maintenance and are built directly on a structure with considerable weight loading capacity, such as a car park.
1.2.2Green walls
Green walls are plants grown in vertical systems that can be freestanding but are generally attached to internal or external walls. Green walls allow for high density and high diversity vegetation on vertical areas and differ from green facades in that the entire support structure is planted, as opposed to a planting at the bottom of a structure that supports vertically growing vegetation. In green walls the vegetation, growing medium, irrigation and drainage are incorporated into the one system. They are also known as living walls, bio-walls or vertical gardens.
Green walls are usually installed to provide an attractive design feature, but can also create cooler microclimates, improve local air quality and sustain greenery in locations where other vegetation could not be supported. A wide range of different plants can be used in green walls, particularly herbaceous materials. Adequate light is an important consideration for all walls, and in some interior settings supplementary lighting is necessary to ensure success.
There are many different proprietary green wall systems available, some largely hydroponic-based, others using a growing medium.
Green walls need a high level of irrigation. Water can be recirculated through the system, but this needs careful monitoring to ensure nutrients do not build up to dangerous levels. The irrigation system often includes addition of fertiliser (fertigation).
The green wall structure can vary from modular systems to sheet or board-based structures with felt pockets supporting plant life.
Selection of a green wall should consider cost, function, quality, lifespan and ongoing maintenance requirements. A well designed system will fulfil its function, have a long lifespan, require minimal component replacement, and sustain growing conditions suitable for the selected species and low maintenance requirements.
1.2.3Green facades
Green facades are created throughthe growth of climbing plants up and across the face of a building, from either plants rooted in the ground,or those in containers installed at different levels up the face of a building. Climbing plants can attach directlyto the surface of a building, or can be supported on a structure independentof the building. Twining or tendril climbers on a support structure enables installation of a green façade not just in front of solid walls, but in front of a window or elsewhere, acting as a partition, privacy screen, sun shade or visually permeable structure.
Green facades are often installed because they provide an attractive look to a building wall or are being used to shield a view or provide shade. Facades generally create a cooler microclimate next to a building through shading and evapotranspiration.All climbing plants will provide some retention of stormwater, cooling of the building, protection of the building, capture of air-borne particulate matter and improvement in air quality, but these benefits will be greater for evergreen species with year-round cover.
For multi-level facades, wind can be a problem for plant attachment. Greening on a support structure is preferred in these situations because twining climbers will be better attached than plants adhering directly on the building façade.The drainage of planter boxes, maintenance access and water pressures must be considered when greening many levels of a tall building.
green roofgreen façadegreen wall
1.3Benefits of green roofs, walls and facades
Increased property prices and other benefits for building owners
Green roofs, walls and facades are increasingly used by building owners to add a point of difference to their building. A green façade or wall can add an element of prestige and beauty to a building. The green roof can be a versatile space used for recreation, urban agriculture or a commercial space for a bar or café. The majority of building owners in Melbourne ignore the potential of the leasable spaces on roof tops, which can be almost as large in area as the floors below them.
The construction of a green roof, wall or façade can happen relatively independently from the rest of a building project and therefore pose very little risk of delaying the construction of a new building. That said it is still very important to include installation specialists in early discussions of the construction project timelines. As “green” design technologies can be retrofitted to old structures, the benefits are not limited to new buildings. Green technologies are capable of rejuvenating ageing structures and thereby increasing property values in the short and long term.
Internationally and in Melbourne, it has been suggested that if a building is more aesthetically and environmentally desirable, there are economic benefits in terms of lease and property values and employee recruitment. Research in Canada estimated that buildings with a recreational green roof achieve an 11% increase in property value, and buildings with views onto green roofs have a 4.5% increase in property value. In Australia, green roofs, walls and facades are increasingly being considered to help achieve points toward the Green Star rating system and NationalAustralian Built Environment Rating Scheme.
Green roofs can lengthen the lifespan of a traditional roof by providing additional protection of the roof’s waterproofing membrane. The green roof adds a layer of organic and inorganic insulation which reduces the stress placed on the membrane by preventing severe fluctuations in temperature. The protection afforded to roofs is especially important in Australia where exposure to ultraviolet radiation can be extreme.
Storm Water Management
Green roofs absorb and retain water and are one strategy for controlling rainwater runoff in urban environments. Green roofs intercept and retain water from the early part of a storm, and limit the amount of run-off in larger storms. Water is stored in the substrate, used by or stored in the foliage, stems or roots of the vegetation, or evaporates off the substrate surface. Additional water storage capacity is available in green roof systems which have a water retention layer. As well as helping to slow and reduce storm water run-off, green roofs can also filter particulates and pollutants.