Introduction
As cities continue to expand to meet socio-economic needs a greater emphasis is being placed on ways in which planners can regulate environmental quality to ensure that urban areas are sustainable. This process includes a rethinking of how we incorporate nature within considerations of what type of places we are developing. Are these interactive, high-density, walkable, and greener places or are we persisting in planning for ideals associated with suburbanization and individualism? Within this space Green Infrastructure (GI)1 has come to the fore as an approach to urban planning that recognizes the value of multi-functional (ecologically and socio-culturally) connected, and diverse landscapes that explicitly support the designing-in of “nature” in its myriad forms. GI has been linked to improved health and wellbeing, supporting personal mobility and connectivity between people, nature, and places, addressing climate extremes, and supports economic development by creating places that people want to live, work, and invest in. However, GI is a not a panacea to the problems caused by urbanization but needs to be considered as a starting point for more nuanced conversations about urban form, function and quality (Mell and Whitten, 2023). Moreover, the ways in which GI is delivered is framed by an ongoing debate related to quantitative assessments of GI needs, i.e., m2 investments and the use of metrics, political thinking within policy directives, and the role landscape/design professionals to integrate the environmental and cultural principles associated with “urban greening” effectively into planning.
Unpacking the links between, and value of, metrics, policy and design is complicated. All are imbued with bias toward specific approaches. For example, ParkScore is used in the USA to denote which city has the best parks system but may fail to take into account local context, whilst the Accessible Greenspace Standard (formerly ANGSt2) embedded within the National GI Standard in England looks at size, distance, and travel metrics but does not readily consider local socio-environmental factors in its analysis (Grace et al., 2025). We can also identify comparable issues with policy aimed at addressing climate change, water management, health and wellbeing, or personal mobility where a lack of holism linking form-function is visible in planning discourse. This is not the case in all instances, but analysis of urban and GI policy internationally suggests a lack of continuity in the alignment of these thematic areas. Finally, there are significant concerns with the use of GI to “greenwash” development (Gałecka-Drozda et al., 2021; de Freitas Netto et al., 2020). High profile architects and landscape architects have employed GI in their work to enhance their ecological credentials, but we could ask whether the ethos of GI, and ecological functionality in the form of provisioning, supporting and regulating services more broadly, is central to such developments? Alternatively, we could argue that GI is used as an attractive screen—to detract planners from the problems inherent with new development. By analyzing how we use metrics within the development process to provide scope for design to be “greener” we can assess the additionality they provide within praxis. We therefore need to consider the ongoing risk of planting the wrong tree in the wrong place—especially in high density urban areas. Poor quality GI investment leads to mistrust in the planning process and a potential dislocation between people and nature (Kendal et al., 2022). It can also reinforce poor design and management practices that perpetuates infrastructure redundancy that subsequently require repeated adaptations to urban green and built infrastructure. Alternatively, by using metrics and landscape-led design within urban planning a more adaptive approach to risk minimization to climate change can be achieved (Grace et al., 2025; Van Oijstaeijen et al., 2020).
The role of metrics in GI development
There is a growing recognition of the utility of metrics in GI planning. They provide guidance, and in some cases legislation, related to the type and quantity of investment needed providing clarity to developers. However, there is a threat that runs parallel as metrics can lead to a “race to the bottom” for investment. As Mell and Whitten (2023) discussed framing GI from a technical perspective adds certainty but metrics should not be viewed as a universal solution—a deeper engagement with the role of metrics within a specific GI/urban context is needed. The distance and size metrics associated with GI delivery in the UK, India and China for example don't effectively take into account local demographic diversity and needs, road layouts, travel/mobility options, types of GI, but do show spatially where things are (Wang et al., 2025). Furthermore, there is substantial evidence illustrating the added societal value of networks of GI to personal mobility by acting a catalyst to engage with nature in urban areas or to move freely by foot or bicycle via the establishment of connected networks of greenways and public rights of way (Hapriyanto and Azmi, 2025). Moreover, current discussion centered on how we deliver a 10% uplift in baseline ecology via Biodiversity Net Gain (BNG) illustrate the complexity of (a) setting a baseline, (b) designing in additionality for people and nature, and (c) the conflicts related to where and what type of GI is developed (Tait et al., 2024). BNG and other climate focused future-proofing approaches, i.e., the use of native species and an acknowledgment of the role of climate adaptive species in design work—commonly viewed as nature-based solutions (NBS)—are thus proposed as core elements needed to support ecological resilience to change in urban areas.
Therefore, although metrics offer a useful grounding to enhance the quantity of GI they cannot be used in isolation to ensure quality delivery. The underpinning research of the National GI Standard in England examined an extensive range of UK and international metrics/standards3 and found complimentary in terms of the use of travel time, distance, and size metrics between countries. Moreover, the use of the Urban Greening Factor (UGF) in Malmo, Berlin and the UK offers a continuity of approach that can provide certainty in terms of what ecosystem services GI will deliver in a specific location (Kruuse, 2011). Unfortunately, developing a green wall, planting street trees, or developing in sustainable urban drainage system in London is not the same climatic or urban context as we find in Melbourne, São Paulo, Singapore, or Toronto. Therefore, the ecological specificity of each location requires a dual universal-bespoke knowledge of species viability to ensure climatic resilient design (Matsler et al., 2021). A transferability of approach can thus be undermined if local context it not taken into consideration to shape investment to a specific place.
Does “green design” equal multi-functional GI development?
The designing-in of GI can be said to elevate the value of these places for all. However, urban greening is also associated with examples of gentrification. Therefore, the planning of greener neighborhoods or landmark projects need to consider the wider socio-cultural impact of investment on all communities. City planners though have historically thought big and bold in their use of GI, and looked to deliver neighborhood or city-scale investment that have the widest reach. The High Line in New York and the Gardens by the Bay in Singapore both offer “wow” experiences but do they deliver an everyday connectedness to nature at a local scale (Jo Black and Richards, 2020; Tan et al., 2013)? Moreover, as nature has been commodified in planning discourses, we have been conditioned to associate GI with progress rather than engaging with the ongoing commentary of who has access to these spaces. What GI gets developed and who the intended beneficiaries are needs careful consideration. It is not enough to invest in more GI, but we need to understand what type of park, trees, water features or facilities are needed. The choice of GI matters climatically, ecologically, and socio-culturally and needs to respond directly to local conditions. There is also a critical need to avoid the imposition of GI that skews existing uses, users or functions. Critiques of Bloomingdale Trail/606 in Chicago highlight the lack of facilities focused on existing community needs (Loughran, 2014), for example. Moreover, the publicity associated with Mayfield Park Manchester's “first public park in a century” failed to acknowledge that the park is a private space with permissive access (Kanellopoulou et al., 2025). Thus, even when GI is created to meet an identified need the inclusivity of such spaces can be inequitable.
Establishing a framework for integrated GI policy
To effectively address the climatic, economic and societal complexities of cities an integrated approach to urban development is needed. This can, and should, draw on the designing-in of nature into all urban areas via the use of horizontal and vertical greening to maximize the use of floor and frontage spaces, the repurposing of redundant built infrastructure as GI, and working toward the creation of spaces that are connected, biodiverse, multi-functional, and accessible to all members of society. The portfolio of GI options available to planners, urban and landscape designers, transport specialists, environmental advocates, and developers thus provides scope to address mobility, biodiversity, health, and economic issues simultaneously.
| How | - Integration of GI thinking into all areas of public policy with the passing of legislation that explicitly places nature/GI at the center of development debates. - Engage with issues of infrastructure resilience via expertise from across the built and natural environment to ensure that ecological, socio-economic, and structural issues are considered in all design/development. - Ensure that the financial value of GI to society is known and supported through appropriate and sufficient funding streams |
| What | - Develop nature-led GI plans for all urban development. - Embed an understanding of the multifaceted functions and benefits associated with thematic framings, i.e., climate change, health, biodiversity, or mobility, at the center if praxis. - Considered GI as a mechanism to deliver multi-scalar and multi-functional enhancements in urban areas. - Work with the suite of GI typologies4 to advocate for the right from/function of investment in the right place. - Plan purposefully to integrate networks of green and blue spaces of all sizes into urban areas to support access and mobility, as well as supporting biodiverse habitats. |
| Who | - Identify GI champions for policy, advocacy, delivery, funding and maintenance within government (at all scales), communities, the private sector/business, the third sector, and within environmental organizations to advocate for investment. - Support an integrated approach to GI development that draws on expertise from the ecological, economic, development, and architectural and structural perspectives to embed resilience thinking in design work. |
4 See for example the typology proposed by (Mell and Scott 2023:14).
Summary
Investing in GI is essential if we are to ensure that our cities are resilient to changes in climate, infrastructure redundancy, health and economic change. The mechanisms used to promote an increased quality, and additional quantities of GI are technical in nature and embedded within policy, practice and legislation. However, advocates are also cognizant that GI is more than the size of a piece of land or its distance from someone's home—it is the role GI plays in supporting health, economic growth, education, personal mobility, social cohesion, climate control, and ecosystem services that contributes to societal quality of life that is equally critical. The applications of standardized approaches are useful, as they add clarity to what GI should be developed, in which place, and how this should be designed. However, the nuance of each location though needs to be integrated with the use of metrics/standards to provide pathways for planners, designers and communities to identify the most effective form of urban greening that is responsive to climatic, economic, and social needs.
Statements
Author contributions
IM: Writing – original draft, Writing – review & editing.
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Footnotes
1.^The paper defines green infrastructure as a network of spaces that connect people to nature, support diverse socio-economic and ecological functions, and provide multiple opportunities for all communities to find uses and attribute values to nature in urban environments (European Commission, 2013; Benedict and McMahon, 2006). The paper also uses a range of terminology: GI, green/blue space, CPs to discuss investment in URFA. We use GI mainly as a framing device as it includes an implicit understanding of “green and blue” spaces being multi-functional, accessible and delivering socio-economic and ecological benefits. Where green space is used it is an overarching term that includes for parks, street trees, gardens, and water bodies and reflects the language used to describe these spaces in the research literature (Mell, 2025:58–60).
2.^The Accessible Natural Greenspace Standard (ANGSt) was developed by English Nature in 1995 to establish a set of time/distance/size metrics to greenspace from a person's home. ANGSt has four main categories (greenspace of at least 2-hectares within 300 m/5-min walk; greenspace of 20-hectares within 2 KM; greenspace of 100-hectares within 5KM; greenspace of 500-hectares within 10 km) plus an additional criterion of at least one Local Nature Reserve (LNR) of 1-hectare in size per 1,000 people (Harrison et al., 1995).
3.^These were assessed against the following criteria: GI Scale (regional/landscape, LPA, neighborhood/site), and against the evidencing of 10 principles promoted by Natural England and Defra within each standard: policy/partnerships, governance, strategic planning, high quality design, multi-functionality/benefits, meets people/community needs, health and wellbeing, biodiversity/BNG, resilience to climate change, regeneration and economic value (LDA Design, 2019, Defra Green Infrastructure Standards, Technical Summary Report, July 2019, unpublished).
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Summary
Keywords
urban greening, planning, climate change, biodiversity, policy, advocacy, metrics
Citation
Mell I (2025) Greening our cities: rethinking the role of metrics, policy, and practice in innovative landscape-led design. Front. Sustain. Cities 7:1709642. doi: 10.3389/frsc.2025.1709642
Received
20 September 2025
Revised
09 November 2025
Accepted
10 November 2025
Published
21 November 2025
Volume
7 - 2025
Edited by
Daniel Jato-Espino, Valencian International University, Spain
Reviewed by
Giannis Adamos, Aristotle University of Thessaloniki, Greece
Updates
Copyright
© 2025 Mell.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Ian Mell, ian.mell@manchester.ac.uk
ORCID: Ian Mell orcid.org/0000-0002-0544-0836
Disclaimer
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.