Grey to Green Transition: mapping a way forward for green walls
- Publication Type:
- Conference Proceeding
- Citation:
- 2021
- Issue Date:
- 2021-10-25
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Youtube: https://www.youtube.com/watch?v=-3KUUGyUwAg
Urbanisation and densification continue to present a unique set of environmental challenges, as declining urban green spaces are intrinsically linked with population growth, urban sprawl and development. Consequently, the loss of green space also comes with increased air pollution, elevated levels of noise pollution, loss of biodiversity and the increase in urban heat island effect. Further, space limitations are characteristically an issue faced in urban areas as green space is often in competition with other land uses or socioeconomic priorities.
Despite these issues, many global cities aim to achieve sustainability targets or green goals in the near future. For example, the City of Sydney’s current goal is to have 40% green cover by 2050, while the cities of Melbourne and Brisbane aim to achieve their 40% green cover targets by 2040 and 2031 respectively. But, it is unknown if it can be achieved with the cities’ current structures and designs.
Increasingly, green walls (GWs) have been considered an adaptive environmental solution to space-limited urban areas while potentially improving the sustainability and regreening of cities. Therefore, evaluation methods are required to allow for appraisal to see if existing walls can be retrofitted with GWs. Furthermore, there is a lack of feasibility studies aimed at quantifying the potential for retrofit suitability of GWs across large urban areas or cities.
This study developed a preliminary evaluation tool for GW suitability in high density urban areas. Using the tool, the quantity of walls across five major Australian cities that could potentially incorporate GWs was determined. Each wall was analysed using a set of criteria that assessed and ranked the wall based on its suitability. Interestingly, major cities across Australia varied in terms of greening potential with the cities of Sydney and Brisbane recording the greatest proportional length of walls suitable for GW implementation, with approximately 34%. Comparatively, the cities of Perth and Adelaide had the least greening potential, with less than 5% for each city, as many walls were excluded due to the prevalence of glazed facades and heritage buildings. Furthermore, Australian cities had very few GWs present with less than 1% of surveyed walls already greened.
These results indicate that cities like Sydney and Brisbane could realistically achieve their targets if they incorporated urban forestry vertically. Though, Perth and Adelaide may need to consider other greening options such as green roofs. These results also highlight the importance of green walls and green roofs as a solution to the space-constrained areas that are characteristic of our urban cityscapes and they offer a green alternative to urban parklands and forestry that may not be viable in the future.
Additionally, the accessibility of this tool will allow interested individuals, communities and organisations to assess the retrofit suitability of an area for GW implementation with minimal requirements in terms of training or resources, and could be applied globally. Subsequently, the outcomes of this study emphasised the need for more governmental support and incentives to encourage GW uptake, and this tool could play a pivotal role in the expansion of green infrastructure and urban forestry.
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