Photo: @danist07

Policy Innovation in Green Infrastructure Governance

by Dr Jason Byrne, Dr Tony Matthews and Dr Christopher Ambrey

Cities are typically hotter than the surrounding countryside because they are constructed from heat-absorbing materials, have extensive paved surfaces, and reflective glass (among other factors).

This situation is termed the urban heat island effect. Heat islands can have negative impacts upon residents’ health and wellbeing, can damage infrastructure, and can reduce economic activity and productivity. This is a problem because more than half of the world’s people inhabit cities — a trend set to increase to around two-thirds by mid-century.

Cooling cities without exacerbating climate change is becoming a key function of good urban governance. Street trees, green walls, green roofs and strategic planting can lower urban temperatures by as much as 8 degrees celsius. Such ‘green infrastructure’ has understandably caught the eye of many policy-makers. The Australian Commonwealth Government, for example, recently established a green cities policy agenda to better understand the benefits and costs of urban greening. The temperature regulation benefits of green infrastructure in Australia are clear; heat accounts for more deaths than any other form of natural disaster. Further, governments across all three tiers (federal, state and local) stand to benefit via savings on health and increases in economic productivity.

Green infrastructure is also potentially attractive to land and property developers. Research has shown that parks and street trees can substantially increase property values. But green infrastructure may have an added benefit. If properties are cooler, this could translate into reduced energy costs — and thus higher returns from commercial spaces. Additionally, consumers’ energy savings will help to drive demand for superior homes and apartments that incorporate green infrastructure. Homebuyers will reap the benefit not only of longer-term energy savings and better resale value but also of higher levels of wellbeing (e.g. improved levels of physical and mental health).

Transit-oriented apartments next to Roma Street Railway Station Queensland, built in close proximity to the Roma Street parkland. Photo: Jason Byrne

Responsible planning and policy

Notwithstanding these potential gains, many gaps remain in our understanding of effective greening initiatives across different scales and climatic zones. Moreover, some major policy challenges lie ahead. These challenges raise an important question for urban governance: How can urban planning systems grapple with adapting to urban heat if policy mechanisms are not designed to differentially respond at the precinct, suburb, district or metropolitan scales? There is much advantage in pre-emptive and strategic policy frameworks designed to address this urban design issue.

For example, decision-making about new urban developments typically occurs at the local scale. Although we have regional and metropolitan planning instruments that identify the preferred future urban form and land use mix, decision-making often occurs in a piecemeal fashion. Development assessment, which is typically undertaken by local councils, is primarily oriented at managing issues such as parking, overshadowing, noise, residential amenity and the like. However, development assessment processes can be modified to include requirements for providing green infrastructure in new built stock. Policies to codify design standards for materials, buildings and space can be embedded within existing development assessment processes, to increase green infrastructure delivery in cities. While improving policy frameworks offers value in ensuring that future built stock performs better when faced with excessive heat, unfortunately it will not help with existing urban stock.

Clearly, we need to better include requirements for urban greening into development assessment. But we also need ways to retrofit existing built environments. Approximately 80% of the buildings that will exist in our cities by 2050 are already constructed.

Policy-led innovations that are designed to support citywide retrofitting of green infrastructure will be crucial. A suite of policy options could be devised. For instance, green infrastructure policy initiatives could be linked to grants that help building owners test the thermal performance of their buildings and improve sub-standard outcomes, drawing from a ‘toolbox’ of approved green infrastructure solutions. Data generated through a scheme like this could be tested and evaluated to identify trends, positive or negative, that can help to further refine policy interventions.

We need to be mindful of a combination of technical and governance concerns. Research shows that urban planners are generally aware of the value and potential of using green infrastructure to cool cities. But many planners and the government departments they belong to are cautious about using green infrastructure. Technical concerns include unfamiliarity with the performance and application of green infrastructure initiatives and uncertainty about potential institutional, legal, economic, social and environmental challenges. We need more research on the species that are appropriate for different urban contexts (e.g. their growth forms, root structures and lifespans). Governance concerns, which generate important policy considerations, include the political context in which planning decisions are made and commitments to budget for green infrastructure delivery and management across different scales of government.

Data is crucial

Some of the existing policy challenges facing governments are related to lack of data about the thermal performance of buildings and the heat absorption characteristics of roads, footpaths, parking lots etc. Many governments lack firm data and therefore reach an impasse on devising policy frameworks in the absence of a compelling evidentiary basis. This ‘knowledge gap’ applies at metropolitan, urban and suburban scales. There is much we still need to learn about the performance of certain materials. While we already know that techniques such as passive heating and cooling, cross ventilation, roof and wall insulation, reflective surfaces and thermal mass can alter the heat-loading of individual buildings, how do buildings perform collectively?

New townhouses in Upper Coomera — where little vegetation leads to thermal inequity for lower income residents. Photo: Jason Byrne

If homeowners choose to use dark tiles on their roofs, pave their yards, have no overhanging eaves and use extensive glazing, they may still be complying with the requirements of both local town planning schemes and the building code of Australia. Yet such decisions can impact not only a resident’s own thermal comfort and energy consumption, but also that of their neighbours. If high-rise building designers and managers choose similar responses, then heat can be magnified across precincts and neighbourhoods. How can urban greening policies regulate private property rights to achieve collective benefits when our systems of governance are geared towards a ‘hands-off approach’ to private property? Resolving that wicked policy problem will not be easy.

Potential resolutions will likely generate greater buy-in if they are based on compelling evidence of thermal performance from a variety of built environment and green infrastructure configurations.

Additionally, we currently only have a rudimentary understanding of how heat problems and policy responses differentially impact a range of urban populations. Much research has focused on inner-urban populations, while surprisingly little focuses on suburban settings. This is particularly anomalous considering that most Australians live in suburbs. The greenest and leafiest suburbs tend to be wealthier while areas of affordable housing typically have poor tree canopy coverage — a situation termed thermal inequity. If we take policy measures such as planting more street trees, requiring more yard space, or mandating a green-cover ratio for houses or suburbs, how might these measures affect poorer residents? Should poorer residents bear the cost of remedying their thermal disadvantage or should some of the cost be borne by government, on the expectation of longer-term savings linked to better health and productivity outcomes? Conversely, should happier and healthier residents of areas with good tree canopy cover pay increased rates or property taxes to reflect their improved thermal equity, lower power bills and the higher capital value of their buildings? This would allow governments to slowly close the gap between ‘winners and losers’ in the spatial and social distribution of urban heat.

A green street verge in Sydney, part of water-sensitive urban design — it also makes for cooler streets. Photo: Jason Byrne

Moreover, while many benefits of urban greening are well known costs must also be considered in urban greening initiatives. In addition to heat moderation, green infrastructure can reduce storm water runoff, lower wind speeds and improve physical and mental health of residents. But planting the wrong species (or even the right species in the wrong places) can increase maintenance costs for renters, property owners and local councils. These include pavement uplift, leaf-clogged gutters, heightened fire risk, overshadowing, root intrusion into water and sewage pipes and even increased respiratory disease (e.g. asthma) from pollens and volatile organic compounds. It is not surprising that these risks, and the fear of associated litigation, can deter policy-makers from fully embracing green infrastructure as an urgent urban policy priority.

Identifying appropriate species that are compatible with local and regional climate regimes is also critical. Further refinement is required to identify appropriate tree species with tight root structures and broad canopies. Testing is also needed to identify distances between planting initiatives and buildings to maximize shade without impeding cross ventilation or overshadowing rooftop solar panels. Species selection for green roof and wall planting also needs to be established through careful testing and research. Interestingly, there is a place for communities in this quest. Thermal performance could most reliably be tested with the involvement of residents’ associations, land and property developers, and ordinary citizens. Any evidence generated would offer potential returns to developers, property owners and governments in the form of profits; direct and indirect savings; and increased revenue.

Partnerships central to green infrastructure delivery

Existing research has illuminated some important policy concerns around green infrastructure delivery, but there are still substantial gaps. We suggest that further research is necessary and that this work is carried out across scales, using a variety of urban buildings and spaces and taking account of the variances between prevailing regional climate regimes. Partnerships between researchers, government and the development industry can refine these efforts and expedite the collection of data. This next phase of fine-grained green infrastructure research can help provide a new evidentiary basis to support new urban policy frameworks that will effect change from the metropolitan to the local scale.

To recap, there are many policy innovations that could support an agenda designed to increase greenery in cities in order to lower heat. Achieving this goal has the potential to produce a wider suite of economic, social and environmental benefits, including, but not limited to, those mentioned above. It is critical that we gather empirical evidence about the performance of different types of green infrastructure in different settings and across different scales. What works in Brisbane may not work in Brussels and what works in Melbourne may not work in Madrid. Meaningfully addressing this challenge will be central to ensuring that future green infrastructure policies deliver on their potential benefits and effect positive change in urban heat management. Establishing policy frameworks to adapt cities to a future with more extreme heat is, quite simply, smart business.



Dr Jason Byrne is Associate Professor of Urban & Environmental Planning with Griffith University’s School of Environment. A geographer and planner, Jason’s research interests address climate change, environmental justice and political ecologies of green-space. He is a member of Griffith’s Environmental Futures Research Institute. Jason previously worked with the Western Australian government as a town planner and policy officer.

Follow @CityByrne


Dr. Tony Matthews MRTPI is a Lecturer in Urban and Environmental Planning at Griffith University. His research interests include managing climate change impacts in urban systems through planning; the role and function of green infrastructure in delivering adaptive interventions; institutional, governance and policy change processes; and community, cultural and spatial rejuvenation led by informal local networks. Dr. Matthews is a member of Griffith’s Cities Research Institute and he co-presents a weekly urban affairs program called The Urban Squeeze with Associate Professor Jason Byrne on ABC Radio.

Follow @drtonymatthews


Dr. Christopher Ambrey is a Postdoctoral Research Fellow at the Institute for Social Science Research at The University of Queensland. Christopher’s research interests are situated broadly within the economics of happiness and ecological economics. He has investigated: the links between the local environment and people’s wellbeing; the determinants of wellbeing more broadly; and different pathways through which wellbeing may be promoted. A self-described reflexive ‘economist with a conscience’, his research increasingly reflects attention to the many and varied forms of injustice. Christopher undertakes research consultancy work for the City of Gold Coast Council, and is variously funded by St Vincent de Paul and the Institute for Social Science Research, for work in homelessness and disrupting disadvantage.