If you’re planning a residential development, house extension or new build in Hampshire, you’ll likely have heard of Biodiversity Net Gain (BNG). Since becoming mandatory in 2024, BNG has added another layer to the planning process, requiring many developments to demonstrate a measurable improvement in biodiversity before planning permission can be granted.
The latest Government changes, effective from August 2026, are designed to simplify the system—particularly for smaller residential developments.
At Peter Tesar Architectural Design Ltd, based in Andover, Hampshire, we work with homeowners, developers and landowners to navigate the planning process from concept through to approval. Understanding how these changes affect your project can help save both time and unnecessary costs.
What Is Biodiversity Net Gain?
Biodiversity Net Gain is a planning policy requiring many developments in England to leave the natural environment in a better condition than it was before development.
Rather than simply replacing habitats that are lost, developments are expected to achieve a minimum 10% net gain in biodiversity through landscaping, habitat creation or, where appropriate, purchasing biodiversity units elsewhere.
While the principle has been widely welcomed, many within the construction and planning industries felt the original requirements created unnecessary complexity for smaller developments.
What’s Changed?
The biggest change is that many residential sites measuring 0.2 hectares or less are now exempt from mandatory Biodiversity Net Gain, provided they do not impact protected or priority habitats.
For many homeowners and small developers, this is welcome news.
Previously, even modest developments could require ecological surveys, biodiversity calculations and habitat management plans before a planning application could proceed. These requirements often added both cost and delay.
The updated regulations recognise that the environmental benefit delivered by very small developments was often outweighed by the time, expense and administration required to demonstrate compliance.
What Does This Mean for Residential Projects?
For clients considering:
- House extensions
- Replacement dwellings
- Small housing developments
- Infill plots
- Self-build homes
- Residential conversions
the planning process may now be considerably more straightforward.
Removing mandatory BNG from many smaller developments means fewer specialist reports, reduced consultant costs and potentially faster planning decisions.
That doesn’t mean every project is automatically exempt. Planning applications may still need to consider trees, protected species, flood risk, conservation areas and local planning policies, but one significant planning hurdle has been reduced.
Why This Is Good News
The revised regulations are likely to benefit the people who often find planning most challenging—private homeowners and small developers.
Many small residential schemes simply weren’t financially viable once additional ecological reports and biodiversity requirements were added.
The latest changes should help unlock more:
- Small residential developments
- Brownfield sites
- Garden plots
- Village infill projects
- Sustainable housing within existing communities
For local planning authorities, fewer small BNG applications should also allow planning officers to concentrate their resources on larger developments where biodiversity improvements can have the greatest environmental impact.
But There Are Still Concerns
While the changes are welcomed across much of the construction industry, they have understandably attracted criticism from environmental organisations.
Although one small development may remove only a limited amount of habitat, hundreds of similar developments across the country can have a cumulative effect on wildlife, mature gardens, hedgerows and urban green spaces.
This remains one of the biggest debates surrounding the revised regulations.
The Government’s position is that larger developments continue to provide the overwhelming majority of biodiversity gains, making the exemptions a proportionate response that supports much-needed housing delivery while retaining environmental protection where it has the greatest impact.
Good Design Still Matters
At Peter Tesar Architectural Design Ltd, we believe good architecture goes beyond meeting planning regulations.
Even where Biodiversity Net Gain is no longer mandatory, thoughtful design can still improve the natural environment through:
- Sensitive landscaping
- Tree planting
- Native planting schemes
- Sustainable drainage solutions
- Wildlife-friendly gardens
- High-quality site planning
These features not only support biodiversity but also create more attractive, sustainable places to live and can strengthen planning applications.
Planning Advice from Local Architectural Experts
Every development site is different, and planning requirements vary depending on location, local planning policy and environmental constraints.
Whether you’re planning a home extension, a new build, or a small residential development in Andover, Hampshire, professional advice early in the design process can help avoid delays and identify planning issues before they become costly.
At Peter Tesar Architectural Design Ltd, we provide architectural design, planning drawings and planning consultancy for residential projects across Andover, Test Valley, Basingstoke, Winchester, Salisbury and the wider Hampshire area. Our aim is to create practical, well-designed homes while helping clients navigate an ever-changing planning system with confidence.
If you’re considering a project and would like expert guidance on planning permission or the latest Biodiversity Net Gain regulations, we’d be happy to discuss your ideas and explain how the new rules could affect your development.
