A sustainability statement is a planning document that sets out how a development responds to environmental priorities — biodiversity, water, energy and materials — and meets the relevant local and national policy. If your council's validation checklist lists one, or your scheme is a major application, you will almost certainly need one. This guide explains what a sustainability statement covers, when planning requires it, and the important biodiversity net gain changes arriving in 2026.
What is a sustainability statement?
Where an energy statement focuses on carbon and Part L, a sustainability statement is broader. It pulls together the environmental credentials of a scheme into one document — typically covering biodiversity net gain, water efficiency, urban greening, sustainable materials and, where required, a BREEAM assessment. It shows the local planning authority that the development is designed to be genuinely sustainable across its lifetime, not just energy-efficient.
When do you need a sustainability statement?
As with energy statements, the trigger is set locally. You typically need one when the local plan or a supplementary planning document requires it, when the scheme is a major development, when the site is in London (where the London Plan applies specific sustainability policies), or when a validation checklist lists it. Householder and minor applications often need only a short statement, if anything — but always check the local list.
What a sustainability statement covers
Biodiversity net gain (BNG)
Under the Environment Act 2021, most developments in England must deliver a 10% biodiversity net gain — leaving habitat measurably better than before, secured for at least 30 years. The statement summarises how the 10% is achieved on-site, off-site or (as a last resort) through statutory credits, drawing on a biodiversity metric calculation.
Water efficiency
New homes are expected to meet the optional tighter water standard of 110 litres per person per day under Part G, demonstrated with a water calculator based on the specified fittings — low-flow taps, showers and efficient WCs and appliances.
Urban greening and BREEAM
For London sites, the Urban Greening Factor (London Plan Policy G5) scores the greening of a scheme — green roofs, living walls, planting and rain gardens. For larger non-residential schemes, councils often require a BREEAM rating (commonly Very Good or Excellent) as evidence of environmental performance.
The 2026 BNG changes for small sites
Biodiversity net gain is changing in 2026. The government is introducing a new 0.2-hectare area-based exemption, expected to take effect around the end of July 2026, which its own analysis estimates will remove the mandatory 10% BNG requirement from roughly half of residential planning permissions that previously needed it. Exempt sites remain subject to environmental protections through the NPPF, but will no longer have to demonstrate net gain on or off site. Other adjustments include changes to the small self-build exemption and to the biodiversity gain hierarchy for minor development. If your scheme is small, it is worth checking whether the exemption applies before commissioning a full metric.
Sustainability statement vs energy statement
The two documents are often confused, and some councils ask for a combined report. The distinction is simple: the energy statement owns carbon — the Part L baseline, the Be Lean, Be Clean, Be Green hierarchy and the London Plan carbon target — while the sustainability statement owns everything else, from biodiversity and water to greening and materials. On a major scheme you may need both. They should tell a consistent story, and a good sustainability statement cross-references the energy work rather than duplicating it.
Sustainable materials and the circular economy
Beyond the headline metrics, planners increasingly look for evidence on materials and waste. That can mean prioritising low-embodied-carbon materials such as responsibly sourced timber, designing for durability and adaptability, specifying recycled content, and setting out how construction and demolition waste will be minimised and diverted from landfill. In London, a Circular Economy Statement is required for referable schemes and sits neatly alongside the sustainability statement. Even where it is not mandatory, a short section on responsible materials strengthens the overall case and pre-empts common officer queries.
How Fortress Associates can help
Fortress Associates prepares automated, site-specific sustainability statements for planning applications across every UK local authority, and the report is free. We cover biodiversity net gain, water efficiency to the 110 l/p/d standard, urban greening and BREEAM where required, so your application arrives with its environmental case set out clearly. Start on our sustainability statement page, reach us through the contact page, or see our full range of services.
Sources & further reading
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