Engineering the future: What biodiversity means for the next generation of design

In 2024, England became the first country in the world to make biodiversity net gain (BNG) a legal requirement for new developments. The change was meant to drive more sustainable, nature-positive growth. But, nearly two years later, many projects are treating the requirements as an obstacle, and they are struggling to move past it.

BNG was designed to make sure that development leaves the natural environment in a measurably (10%) better state. In practice, the process has proved complex and often slow. Developers cannot break ground until their biodiversity gain plans are approved by the local planning authority and, for many, this has led to delays.

One issue seems to lie with off-site schemes, where biodiversity improvements are delivered away from the main development site. Legal agreements for these schemes are taking months to secure, leaving many projects stuck in planning.

Another challenge is that, depending on the site, the targets can be quite ambitious. Even unremarkable brownfield land can be surprisingly biodiverse, so reaching a 10% gain can be harder than it sounds, particularly on larger or more complex developments. It is not surprising that many developments rely on off-site solutions to deliver their gains.

Too often, biodiversity is considered too late in the process

The problem is not with the principle of BNG itself, but with how it is being applied. Off-site credits were intended as a safety net, not a default solution. By depending too heavily on them, design teams risk missing opportunities to deliver biodiversity through the core of their landscape and drainage strategies.

Too often, biodiversity is considered too late in the process. By the time it is discussed, layouts are fixed, budgets are tight and space is limited.

This becomes even more challenging where existing habitats are already rich, because a higher starting biodiversity makes the 10% increase harder to achieve. Unlocking on-site biodiversity requires early design input, giving teams the flexibility to identify opportunities and build upon what is already there.

Architects, engineers and landscape designers all have a role to play in changing this mindset. It is up to design teams to bring these disciplines together early, as developers rarely will. When civil engineers, landscape designers and environmental consultants are involved from the start, biodiversity can be built directly into infrastructure design, making on-site delivery both achievable and sustainable.

>> Also read: Biodiversity net gain: A crucial but complex step towards nature recovery

>> Also read: OMH – BNG is not working

The principles needed to achieve this are already familiar to engineers who work with sustainable drainage systems. SuDS are a prime example of how well-designed infrastructure can deliver multiple environmental outcomes, and when they are fully integrated into the landscape vision, they can also make a meaningful contribution to BNG. 

By working with natural processes such as filtration, sedimentation and infiltration, and incorporating vegetation and permeable materials, SuDS can improve water quality while creating valuable habitats. A retention basin designed to provide both water storage and wetland habitat, or a smaller-scale bioretention area which filters run-off while supporting diverse, pollinator-friendly planting, can deliver measurable biodiversity gains alongside effective surface water management.

Well-designed bioretention areas, even within tight urban plots, can provide valuable opportunities for BNG through species-rich planting and multifunctional design. Systems that use vegetation and natural filtration improve water quality by trapping sediment and removing pollutants before run-off reaches rivers or streams. Planting schemes with a mix of species cope better with extreme weather, improving reliability and reducing long-term maintenance.

With the right approach, it can achieve what it set out to do

Integrating these principles from the outset not only helps to meet legislative requirements but also creates landscapes that deliver value beyond compliance. When SuDS and biodiversity considerations are embedded at the concept design stage, projects demonstrate clear ecological benefits from the start, reduce administrative complexity, and move through planning more smoothly. The outcome is infrastructure that performs effectively, provides long-term value for money, and enhances environmental resilience.

Design teams and developers need to adapt faster. BNG is not going away, and the regulations continue to evolve.

Treating BNG as a planning obstacle will only slow things down. With the right approach, it can achieve what it set out to do – help deliver greener, more sustainable and resilient spaces – but only if design teams take the lead in making it work.