New planning legislation that aims to boost biodiversity in development projects will come into effect in England in January. Here, Dezeen explains what architects need to know.

What is biodiversity and why does it matter?

In this context, biodiversity usually refers to the variety of all species living within a certain area or ecosystem, including plants, animals, insects, bacteria and fungi.

Each species in an ecosystem has its own impact on the environment, affecting the availability of clean water and air, soil condition, pollination and other food sources and resources. Variety is necessary to keep all these elements in balance, maintaining a stable and resilient world for humans to survive in.

Many parts of the world are experiencing rapid biodiversity loss as a result of phenomena caused by human activities, such as pollution, climate change and habitat destruction. A Queen's University Belfast study published earlier this year found that 48 per cent of the world's animal species are experiencing population decline. The Worldwide Fund for Nature claims we are witnessing the sixth mass extinction event in the Earth's history.

"We live in a time of mass extinction, where an alarming number of species are disappearing and where the impoverished ecology of the planet is having a detrimental effect, not only on our climate emergency, but also on pollination and in the production of food," Adam Architecture director Hugh Petter told Dezeen. "It is a powder keg."

Adam Architecture's work includes Nansledan, an extension to the British city of Newquay that is being designed for the Duchy of Cornwall. The studio says it will surpass the new biodiversity net gain rules by adding "habitat 'units' of around 24 per cent and an increase in hedgerow 'units' of around 48 per cent".

What are the new rules?

Construction can be a major cause of direct biodiversity loss, and the new planning rules for England aim to address that. They mandate that new developments deliver a "biodiversity net gain" – that is, a measurably positive impact on biodiversity compared to what existed before.

Specifically, the legislation requires developers to deliver a biodiversity net gain of 10 per cent. To calculate this, the UK government has produced a formula called the "statutory biodiversity metric" for counting what it terms "biodiversity units", which are gained through work to create or improve natural habitats and lost through building.

As they strive to meet the 10 per cent requirement, developers must prioritise enhancing biodiversity on-site. If they cannot meet the threshold on the site being developed, they will be allowed also to make biodiversity gains on other plots of land, including by purchasing biodiversity units from other landowners.

As a last resort, they must buy "statutory biodiversity credits" from the government, which will use the money to invest in habitat creation. Biodiversity gains delivered must be maintained for a minimum of 30 years by whoever owns the land, bound by legal agreements.

Once planning permission is granted for a project, the developer must submit an evidenced biodiversity gain plan to the local planning authority (usually the council), which will approve it or refuse it. Development can only start once the biodiversity gain plan is approved. If the developer then fails to act in line with their biodiversity gain plan, the planning authority may take enforcement action.

Guidance on the new legislation, including a step-by-step guide to compliance, is available on the UK government's website.

When do they come into effect?

The legislation was initially intended to come into effect for large developments of more than 10 dwellings in November, but that was pushed back to January 2024.

Smaller sites will also be subject to the new rules from April 2024, while major infrastructure projects will have to comply from late November 2025.

Some sites, such as small custom-built housing developments, will continue to be exempt.

What do architects and landscape architects need to know?

Architects and landscape architects will likely play a leadership role in ensuring that projects deliver on biodiversity requirements, working with ecologists and the authorities.

The most important thing, says Petter, is to understand the importance of biodiversity loss as an issue.

"The more architects can take a proper interest in the subject, the better placed they will be to work with the spirit of the new legislation and to think of imaginative ways that the minimum standards can be exceeded," he said.

"It is crucial to engage with an ecologist as soon as possible," added RSHP sustainability lead Michelle Sanchez. "It is also beneficial to evaluate the site as soon as you gain access."

"This enables you to develop your designs based on the existing level of biodiversity, tailoring your strategy to local flora and fauna you particularly would like to support," she said.

One thing to bear in mind is that the new rules aim to prioritise avoiding biodiversity loss in the first place.

"Avoiding biodiversity loss is the most effective way of reducing potential impacts, and it requires biodiversity to be considered at early design stages," the guidance states.

To gain planning permission for a project that does cause biodiversity loss but proposes strategies to replace it, developers will need to explain, with evidence, why avoidance and minimisation is not possible.

Will this actually help to boost biodiversity?

The rules will mark the first time biodiversity enhancement has been a planning condition in England. According to University of Oxford researcher Sophus zu Ermgassen, it represents "one of the world's most ambitious biodiversity policies", but the exact impact is not yet certain.

But Sanchez is broadly optimistic. "Developers were not inclined to consider biodiversity enhancement in the past," she told Dezeen.

"Only on projects attaining sustainability certificates such as BREEAM would biodiversity targets be discussed. Even then, it would sometimes more regarded as a tick-box exercise rather than an opportunity to make the building better and more appealing and to reduce the environmental impact that architectural projects have on the planet."

However, she has warned in an opinion piece for Dezeen that a 10 per cent net gain on its own "is not enough to be able to reduce the negative impact that our way of life has had on biodiversity".

The photo is by Free Steph via Unsplash.