In Conversation; Embracing Biodiversity Net Gain

Published on 11th April 2025 by Wendy Perring

Embracing Biodiversity Net Gain – A Collaborative Approach

Following on from our last insight post where we discussed being led by the landscape in the design phase with James Hamilton from SEED landscape, we will look at Biodiversity Net Gain (BNG) an emerging concept in the field of architecture and landscape design, aimed at leaving the natural environment in a measurably (quantifiable) better state than before. As architects, collaborating with landscape architects, we have the opportunity to enhance biodiversity on our projects, creating spaces that are not only functional but also environmentally enriching.

We have worked extensively with SEED over the past five years on a number of projects, including a current project in Hertfordshire for a rural house for two engineers which is set adjacent to an ancient woodland on a large site of several acres. This was won at appeal and is about to start on site and at the planning stage we had to demonstrate a 20% Biodiversity Net Gain. This piece is based on a discussion with James Hamilton, Director at Seed Landscape, which took place on Tuesday, 25th February.

What is Biodiversity Net Gain?

BNG is about increasing wildlife on site, creating more opportunities for various species. James Hamilton explains, “In layman’s terms, it’s just increasing wildlife on site, creating more opportunities for more species.” This approach involves integrating biodiversity considerations from the very beginning of a project, rather than as an afterthought.

Why is BNG Pertinent Now?

The urgency of addressing biodiversity loss has never been greater. With increasing urbanisation and climate change, the natural habitats of many species are under threat. BNG provides a framework for reversing this trend. James notes, “At the moment, there’s a bit of a tick box with biodiversity net gain, where you try to shoehorn biodiversity into a scheme, but we approach it from the very beginning with our site analysis and baseline of what we can do to improve the site.”

Our Approach to BNG

As architects, our collaboration with landscape architects is crucial in achieving BNG. From the initial site analysis to the final design, we work together to ensure that biodiversity is a key consideration. James highlights the importance of early involvement: “Our favourite projects are those where we’re involved right at the beginning, influencing the location of the building and having initial discussions about what we could do.”

Addressing Misunderstandings and Fears

There is often a lack of understanding and fear surrounding BNG, with concerns about complexity and cost. However, BNG is not something to be feared but rather an opportunity to create something great. James reassures, “You can leave a bit of your garden wild to increase biodiversity. Deadwood can be used to create hibernaculums for invertebrates. Big moves, like putting a meadow in improved grassland, take more effort and money, but there are ways to enhance biodiversity over time with small interventions.”

The Real Opportunity

BNG offers a real opportunity to enhance the environment and create spaces that are not only beautiful but also beneficial for wildlife. James shares, “Creating an opportunity for one species creates opportunities for others. For example, a woodland edge creates insect biomass, which promotes invertebrates and birds, leading to an explosion of diversity. It changes the feeling of the site over time.”

Conclusion

Biodiversity Net Gain is a vital concept that architects and landscape architects can embrace to make a positive impact on the environment. By understanding and integrating BNG into our projects, we can create spaces that are not only functional and aesthetically pleasing but also rich in biodiversity. As James Hamilton aptly puts it, “It’s not just a technical thing; it completely changes the feeling of that site over time.”

Summary of the Interview with James Hamilton

Q: What drives biodiversity enhancement in your projects?
James Hamilton (JH): We try to incorporate biodiversity enhancement in every job, starting from the site analysis and baseline improvements. This applies to both domestic and commercial projects. It's essential for landscape architects to increase biodiversity on site, whether through large-scale projects like introducing meadows or woodlands or smaller domestic projects involving bird boxes and sustainable drainage systems.

Q: How do you approach new projects as landscape architects?
JH: Initially, we have conversations with clients to formulate a personal brief. We respond to the site both analytically and emotionally. For example, in a project in Salisbury, our emotional response to the big sky and horizon influenced the building's placement. Drawing is a significant part of this emotional response, with raw sketches often expressing more than polished drawings.

Q: What does landscape enhancement mean to you?
JH: It's about being realistic about what can be enhanced. We prefer projects where the landscape is already disturbed, like brownfield sites or improved grassland. If a site is too sensitive, we might decide it can't be a paragraph 84 project. It's important to understand the context and what can be realistically improved.

Q: What makes a good collaborative process with architects?
JH: Early involvement is key. Our favourite projects are those where we're involved from the beginning, influencing the building's location and having initial discussions about potential improvements. Constant collaboration throughout the process, even in later stages with materials, is crucial.

Q: How do you address misunderstandings and fears about BNG?
JH: BNG is not something to be feared. Simple actions like leaving parts of a garden wild or using deadwood to create habitats can increase biodiversity without significant cost. Larger moves, like creating meadows, require more effort and money, but small interventions over time can also be effective.

Q: How do you approach biodiversity enhancement on urban sites?
JH: We look at the historical context and incorporate elements like old orchards or woodlands into the scheme. Increasing the variety of species, adding pools of water, and using bird boxes and foraging plants are effective ways to enhance biodiversity in urban settings.

Q: Does biodiversity enhancement need to be expensive?
JH: No, it doesn't have to be costly. Simple actions like leaving parts of a garden wild or creating habitats with deadwood can increase biodiversity. Larger projects, like creating meadows, require more effort and money, but small interventions over time can also be effective.

Q: Why is it challenging to improve grassland that has been in farm use?
JH: Nutrients are the main challenge. Reducing nutrients in the ground, sometimes by scraping it off and leaving it fallow before seeding, is necessary. Over-seeding with species like yellow rattle can help push out dominant grass species, but it's a battle.

Q: What opportunities exist within the construction of a landscape and building to create biodiversity?
JH: Soil inversion, where nutrient-lacking soil is placed on top, creates opportunities. Wildlife likes nooks and crannies, so even removals can create habitats. This approach saves money and benefits the environment.

"Creating an opportunity for one species creates opportunities for others.
For example, a woodland edge creates insect biomass,
which promotes invertebrates and birds,
leading to an explosion of diversity. It changes the feeling of the site over time."

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