Requirements on structures such as single houses have been burdening local authorities and developers with regulations that should be focused on larger projects, said Peter Massini, director of Future Nature Consulting.

“The idea that you remove the ‘de minimis’ exemption completely is utter madness, because you’d be saying to someone who’s losing a non-native shrub in their garden that they need to do BNG,” Massini told Carbon Pulse.

“I think developments under 0.25 hectares (2,500 sq. m) should be largely exempt from BNG.”

The small sites, or de minimis, exemption is for sites impacting less than 5 x 5 metres of on-site habitat, or 5 m of hedgerows.

Developers in England have had to plan to boost nature by 10% since February under BNG requirements. The policy has been praised as world-leading, but over the last couple of months some market actors have asked for the removal of the small sites exemption.

In September, eight NGOs and business groups asked the government to remove the “loophole”, saying it was stifling demand by allowing some developers to opt out of their environmental responsibilities.

Proposed English house site requiring 0.03 off-site BNG units. Credit: Massini

Massini stressed that he was in favour of nature uplift, but said the requirements were unnecessary for smaller developers. Larger developers would usually find it easier to generate on-site gains than smaller ones, as they have more options on their land, Massini said.

When developing a small site like a garden shed – affecting one or two units under the BNG metric – there is limited opportunity for on-site development, he said.

“Because those sites are small, they’ve got very little room for manoeuvre. If you lose one or two trees, you’re suddenly faced with a real problem, either having to go off-site or buy statutory credits,” he said. The credits are a more expensive last-resort option for developers.

BNG has a disproportionate impact on small sites because their baseline biodiversity value is usually low. With a 10% relative change target, even minor alterations can lead to significant swings in biodiversity net gain – resulting in anything from 20% loss to a 50% increase, he said.

A simpler alternative to BNG might be a levy on small sites, Massini said. The charge would be based on the amount of lawn or trees being lost, with funds going to the local authority to be used for tree and hedge planting.

LIMITED BUYING OPTIONS

For those small sites looking to buy a small number of units to deliver a 10% increase, there are limited options, with many habitat banks not offering transactions of 0.1 units, he said.

Applicants with “negligible impact” have to go through the process equivalent to that of large developers: funding a BNG assessment, acquiring approval from a local planning authority (LPA), finding off-site units, and paying administration costs.

“The small developers are being penalised for being a small developer. A lot of people are now recognising this as a problem.”

Proposed English house site requiring 0.06 off-site BNG units. Credit: Massini

Furthermore, few small sites have applied for planning permission so far, as developers waited to observe how BNG played out, creating a looming problem.

“They’re now starting to go through the system, and LPAs are going to get swamped by loads of information about small sites where the impact is negligible.”

Local authorities have struggled with BNG since the legislation came into force, although the issues were said to have been improved by changes to the bodies approving conservation agreements over the last few months.

“LPAs, who are hard pressed, should be focusing their attention on the bigger sites,” Massini said.

“Natural England said LPAs should triage applications but no one knows what that means. Because BNG is a legal requirement, LPAs feel obliged to scrutinise every single application.”

“USELESS” METRIC

The management of small sites has been further complicated by their measurements. BNG is underpinned by two metrics: a simpler one for small sites, and a more complex one for large sites.

If small sites do not reach the required 10%, they need to move all the data into the large sites metric to find out how much is missing, said Luke Mills, director at Landscape Service, in an article on LinkedIn this week.

This “not only doubles your workload, but renders the small sites metric completely useless”, Mills said.

“Also, the small and large sites metrics aren’t like-for-like. It’s harder to achieve 10% on the small sites metric as it doesn’t allow you to state an existing tree’s condition, it rates all trees the same regardless of condition.”

Indeed, when assessing a small site, the small sites metric often assigns a higher habitat value than the statutory metric, as the latter has more options for assessing habitat condition, said Massini.

As a result, some ecologists working on small sites prefer using the statutory metric, he said.

By Thomas Cox – t.cox@carbon-pulse.com

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