Biodiversity Net Gain at Winterstoke Hundred


The Winterstoke Hundred Academy is a new school established in 2020 in the premises of a 2016 building. Due to its location at the edge of Weston-super-Mare’s rapidly growing Winterstoke Village housing development, North Somerset Council recently commissioned an expansion to the school which would deliver places for 900 more pupils.

The council’s initial assessment suggested that delivering 10% biodiversity net gain (BNG) was unlikely to be possible on site, so a costly offsite land acquisition and restoration programme would be required. However, we looked at the site plan and suggested changes to preserve existing biodiverse features and create new management regimes . These enabled 11% BNG to be delivered on site.

Kier’s final proposal described a zero carbon building within a wider development which delivered 11% BNG. As North Somerset Council were an early adopter of the BNG legislation, exceeding the target and delivering onsite BNG gave Kier a winning edge over the competition in their bid for the work.

The Ecosulis team was involved from the very start of the project, supporting the bid team right through to RIBA Stage 5. To ensure biodiversity and retained habitats were protected during construction, we provided ecologists to monitor and advise on this stage of the project.

Project brief

Biodiversity Net Gain legislation will require developers to deliver 10% or more improvement in biodiversity on sites in England from 2023. However, many contractors and local authorities are rolling out this framework in advance, and Ecosulis has already been delivery significant gains on these projects.

To comply with the legislation, developers must conduct a baseline survey of the ecosystem and propose restoration, avoidance, mitigation and habitat creation solutions to hit the target of 10% biodiversity net gain. This may include the purchase of premium biodiversity credits, offsite habitats work or land bank purchases. However, the most cost-effective route to 10% BNG is typically on-site ecosystem restoration, particularly if the protection and management of these habitats is guaranteed.

Ecosystems created through BNG schemes must be protected for 30 years under the BNG rules – this favours the creation of self-sustaining habitats. As a result, developers have been exploring rewilding options, where ongoing maintenance costs are low and biodiversity output is generally high. As the UK’s first rewilding specialist and one of the top ecological consultancies, Ecosulis is well-placed to advise on such schemes.

"Ecosulis provided outstanding ecological consultancy, which played a fundamental role in our end solutions. They worked closely with our internal design team to develop an innovative BNG solution as part of a complex greenfield project."

Emma Higgs, Kier Construction


2021 - 2022


manage Biodiversity

The innovative design measures proposed by Ecosulis for this project will result in a long-term biodiversity net gain of around 11%.

Protect Habitats

The habitats specified by Ecosulis will create or restore a wide range of important features such as hedgerows, ponds, grasslands and woodland, enabling them to host a greater abundance and diversity of wildlife.

empower-us-to-act People

In addition to designing a richer local environment which the children of the school can enjoy, Ecosulis also delivered a suite of educational engagement activities, to improve understanding and appreciation of local biodiversity.

How we added value

Solution and Results

Rather than focusing on costly offsite or credit-based offsets, Ecosulis identified innovative interventions which would allow Kier to deliver an estimated 11% biodiversity net gain on site. These measures included the creation of woodland and ponds, enhancement of hedgerows, the installation of nest boxes for bats, swifts, sparrows and barn owls, and changes to grassland management regimes.

This solution was not only popular with the council, but also the school, as it aligned with their goals. Their curriculum has an environmental science specialism, so Ecosulis also provided lessons to engage pupils with the development project.

Teaching apprentices at Kier
Winterstoke Hundred school expansion
Minimal and cost effective…

The minimal interventions used at Winterstoke Hundred Academy were designed according to our rewilding principles, to enable natural regeneration of ecosystems. This will create self-sustaining habitats which ‘heal’ themselves and connect the wider landscape, boosting biodiversity. These interventions are extremely cost-effective, not only delivered on site but with little ongoing maintenance costs.

The BNG calculations on this site were performed using the now-superseded Biodiversity Metric 2.0. A 3.1 metric is now available, and updates to this standard will continue to be released over time. However, we have been working for a decade on a complementary, algorithmic method for measuring biodiversity and identifying cost-effective interventions. Our innovative system, NARIA, addresses many of the criticisms levied against 3.1 by scientists and developers. 

Want to learn more about rewilding and nature recovery?

Read more insights or explore our previous work.