Green Infrastructure

25 August 2022

The recent growth in awareness of how human activity is impacting the natural world has led to a widespread desire to make an active difference before it’s too late. Responding to the threat of the climate emergency and biodiversity crisis, the development sector has been focusing on reducing its environmental impact, whilst promoting the environmental and ecological benefits which can be achieved through careful scheme design.

With the Environment Act 2021 mandating that new developments in England must demonstrate a minimum 10% biodiversity net gain, integrating green features into every scheme is now key to project success. This mandatory requirement will be enshrined within new Regulations which are expected to come into force in November 2023 and will take account of the outcome of government consultation that closed in April 2022. The Act will also establish the Nature Recovery Network and Local Nature Recovery Strategy as a mandatory system of spatial planning for nature, which will create a national wildlife-rich network at a landscape scale.

Coupled with this rising environmental awareness and the recent legislative shift, the COVID-19 pandemic has also fundamentally changed the way we utilise outdoor spaces, with parks and green areas offering somewhere to socialise and interact, and becoming vital places for people’s wellbeing and health. Elsewhere, our streets have been pedestrianised and pavements widened to create outdoor seating areas outside cafes, pubs and restaurants, and this change in approach to the way the public realm is utilised represents a significant opportunity to increase green infrastructure (GI) in urban areas. Spending time exercising, relaxing and socialising in green spaces is also proven to boost mental health and wellbeing, and green urban spaces can bring many other benefits. From increasing biodiversity through targeted native species planting schemes, to integrating Sustainable Drainage Systems (SuDS) which maximise resilience to our changing climate, these features can be included in developments of all sizes.

By incorporating a network of high-quality green spaces and environmental features, projects can have a significant positive impact on natural processes whilst providing key habitats to enhance the biosphere. Tom Hurlstone, Waterman’s Associate Director for Infrastructure & Environment, said: “These features have become increasingly prevalent in new schemes where GI is integral to the design principles, and features such as SuDS, green roofs and living walls have been included in new developments for some time. However, there is now a greater emphasis on providing a more holistic approach to GI design. In the capital, for instance, the current London Plan dictates that a development’s ‘Urban Greening Factor’ must meet minimum standards, and this has meant that developers must clearly demonstrate how GI is integrated in a scheme from the beginning of the design process.”

Predicting a UK-wide adoption of a similar methodology, Tom said: “It is likely a standardised, nationwide approach will emerge which will allow the selection of GI elements that are most appropriate to a given scheme. A flexible Urban Greening Factor would encourage GI delivery for all site contexts, conditions and land values to meet the recommended targets. For the first time, this would allow the benefits of engineering and environmental input to be calculated relative to their contribution to GI.”

Despite ever-increasing pressures on budgets and the limited availability of open space, the positive effects of GI features are becoming more widely documented across the UK. Highlighting the next steps for the successful widespread integration of GI features, Tom said: “We are seeing them embedded in a growing number of projects. However, there is still some way to go to ensure these are considered right from the outset of the design process. Early consideration always helps to reduce abortive design work and provide commercial certainty of developable areas, whilst enabling robust support throughout the planning process. The benefits of these features are clearly demonstrable, and I am confident that they will become much more prevalent over the coming years.”

With the effects of the climate emergency causing increasingly unpredictable weather conditions such as heat waves, storm events and floods due to heavier rainfall, our cities must become more resilient as the frequency grows. In recent years, SuDS have become an essential part of many designs as the impacts of urbanisation become more severe. Highlighting the role played by these systems, Tom said: “SuDS work by mimicking natural drainage processes and provide a method of surface water drainage which takes account of a site’s attributes and ecological issues. The correct application of the SuDS hierarchy can contribute hugely to the flood resilience of a development. In practical terms, this means an urban site might place greater reliance on SuDS features, green roofs and street trees, whereas a suburban or rural site could perhaps utilise rain gardens, woodland blocks and areas of open water. One recent example of this tailored approach was seen when our team established the appropriate system for the 187-ha self-building housing scheme at Graven Hill. Here, our flood and drainage team designed a SuDS drainage swale that provided multiple environmental, engineering and economic benefits.”

Low-impact solutions can also deliver superb results, with existing natural features retained and protected. Tom highlighted a recent scheme where our team took just such an approach: “Retaining existing mature trees with Tree Preservation Orders at the Axis Square project in Birmingham allowed us to include boundary trees that will assist with the management of pollution, climate moderation and rainfall attenuation within the proposed design, as well as helping to increase adjacent land values. The retention of existing trees maintains strong biodiversity and contributes to meeting Biodiversity Net Gain (BNG) targets, whilst also helping to protect natural wildlife corridors to give British flora and fauna a helping hand.”

Helping developers include more blue and green infrastructure in their projects and achieve a BNG in an accountable and structured manner, Waterman has been at the forefront of BNG calculation and management from its inception. Tom said: “Since 2013, our specialists have been working with clients to help them assess and improve the biodiversity impact of their schemes. We do this by applying previous versions of the Defra metric to their projects to help them deliver positive ecological impacts and secure planning consents. The pre-Defra Biodiversity Metric process involves establishing a detailed project management and Biodiversity Impact Assessment calculator, developing an ecology survey calendar, compiling species planting lists, and assessing both national and local priority habitats and species lists to facilitate highly effective ecological design.”

Discussing the support available through our team for achieving BNG, Tom said: “The best results are often achieved through early engagement, and our experts begin working with design teams from the earliest feasibility stages, exploring options for achieving the minimum 10% BNG and ensuring that potential opportunities are maximised through the emerging scheme design. We then support the integration of the chosen measures via planning conditions, obligations or conservation covenants, and continue to provide guidance through to detailed design and on to the post-construction monitoring stages.”

To find out more about embedding green infrastructure features in development design and achieving biodiversity net gain, contact our Associate Director for Infrastructure & Environment, Tom Hurlstone (mailto:, our National Ecology Lead, Diane Corfe (mailto:, or our Principal Ecologist, Lee Mantle (mailto: