Green infrastructure for denser cities
As cities grow and become denser, we need to promote green infrastructure as a utility that improves resilience and health
Report from – Peter Massini
Olympic Village SuDS (Image courtesy of the author)
London continues to grow. Its population is expected to be circa 11 million by 2050. There is a widely held view that this growth must be contained within London’s boundaries. This is not only to protect the Green Belt, it is also because a compact city can be a more sustainable city by encouraging high rates of public-transport use and efficiencies in the use of energy and water.
However, there is an understandable concern that increasing growth and density will result in continued loss of green space and a growing disconnection of people from nature. So how can a city with more homes, hospitals, shops, schools and businesses be a greener city that meets the aspirations set by a raft of policy ranging from the UN Greener Cities agenda, the EU Nature based solutions initiative and UK policy in the Natural Environment White Paper?
Re-framing our terms of reference
It will firstly require a shift in thinking about our understanding of ‘green space’, ‘public realm’, the ‘built environment’ and the relationship between them, because although these catch-all terms, derived from land-use planning policy, define form, they say little about function. Green space is merely that which is not built upon; public realm describes the civic space between buildings, and the ‘built environment’ lumps together every architectural form into a fusion of stone, brick, concrete, glass and steel, which is often regarded as the antithesis of the natural environment. This has resulted in green city policies being framed simply around the protection of green space (and nature) from the built environment and improving the aesthetics of the public realm by, for example, planting street trees.
Consequently urban planning, architecture, and urban design has – until relatively recently – been practiced in order to achieve the necessary balance between grey and green, hard and soft, artifice and nature. In the UK, city planning frameworks such as the London Plan have been reasonably good at mediating this compromise and guarding against wholescale loss of green space. But it is difficult to see how this traditional policy approach can continue to work as cities grow. Cities are, after all, a manifestation of our ability to build, engineer and fashion the landscape to meet our cultural and economic needs.
These needs include the benefits provided by a green city but, when trade-offs need to be made, we have not always been able to articulate these benefits in a way that is as compelling as the arguments for new housing, hospitals, schools and transport infrastructure.
Green infrastructure as a utility
We have to craft a more sophisticated and nuanced green city policy framework that promotes an integrated network of parks, green roofs, trees, rain gardens, green walls and green corridors that act as a ‘green infrastructure’. A clunky term, perhaps, but one that describes better how these green elements of the city’s fabric can be planned, designed and managed and, dare I say, engineered, to provide services that are essential rather than optional or nice to have.
London has been moving in this direction. By restoring rivers to create new flood storage capacity and improve ecological connectivity, and by beginning to implement sustainable urban drainage to relieve growing pressure on the surface water drainage system, we have begun to demonstrate how a green infrastructure approach can enhance both function and form of a space. London has also had considerable success in encouraging the installation of green roofs, green walls and rain gardens, particularly in the heart of the city and across central London where opportunities resulting from regeneration or public realm improvements by public/private partnerships provide the catalyst for change.
But we do not yet ‘plug, plumb and connect’ green infrastructure in the city in the same way as we do other critical infrastructure. We need to consider how it is planned and delivered at a scale beyond the individual green space or development. Isolated greening interventions are beneficial but are not transformative per se. It is when these are designed and delivered in a way that addresses both a site-specific need and the landscape-scale challenge (such as surface water flood management, air quality improvement, biodiversity conservation or modal shift to walking or cycling) that it becomes an infrastructure that is networked and systematised in the same way as water, power, transport and digital services are provided. Guidance is beginning to be developed that helps promote this systems thinking approach. For example, Trees in the Hard Landscape published by The Trees and Design Action Group and Lewisham Council’s River Corridors Improvement Plan acknowledge the importance of landscape-scale, holistic thinking that helps to integrate rather than separate green and grey.
This more utilitarian view of green infrastructure is anathema for some because it seems to detract from the intrinsic value of green space and nature. But making the case for the utility of green infrastructure simply provides an additional argument for why the cities which are likely to become denser and more populated in the future need to be greener. A greener city is one that does not differentiate between the natural environment and built environment, between ecologist and architect, or between park and public realm. It is a city that embraces the concepts of green infrastructure and nature-based solutions in order to create an urban form that is not a compromise with nature, but a collaboration with it.
Peter Massini is Principal Policy Officer – Green Infrastructure at the Greater London Authority.