Biodiversity Net Gain (statutory)

Overview

Biodiversity Net Gain is a statutory requirement in England under which most new development must deliver a measurable improvement in biodiversity of at least 10 percent compared with the pre development baseline. Biodiversity value is calculated using the statutory biodiversity metric, which scores habitats by type, condition, size, and strategic significance to produce biodiversity units. Eligible activities include on site habitat retention, enhancement, and creation, and off site habitat works, with the gains secured and maintained for at least 30 years. One biodiversity unit represents a standardised measure of habitat value derived from the metric.

Sources: methodology document · UK Biodiversity Net Gain

01 · Roles

The workflow as an explicit directed graph. In Graph each column is one role, so you can see who acts at each step; every node names the org.broadlistening.policy.block.* def it resolves to plus its input and output record. Data flow switches to a lineage view that makes explicit what data each node needs and makes, with dependency arcs tracing every record back to the node that produced it, including where the Darwin Core occurrence + measurement records feed in. Hover to trace, click to inspect; revise edges (dashed) send work back.

03 · Generated lexicon records

The records this methodology compiles to, ready to write to a PDS. The first tabs are the new policy engine records; the ★ claim.activity tab and those after it are reused ATProto Collective Funding Ecosystem records (org.hypercerts.*): the issued hypercert batch, its rights, an example verification attachment and a retirement receipt. The ◈ dwc.occurrence and ◈ dwc.measurement tabs are the Darwin Core field evidence the monitoring node writes; see the section below.

{
  "$type": "org.broadlistening.policy.methodology",
  "code": "UK BNG",
  "name": "Biodiversity Net Gain (statutory)",
  "registry": "UK Biodiversity Net Gain (BNG)",
  "sector": "Compliance (UK)",
  "creditType": "biodiversity",
  "status": "active",
  "version": "1.0",
  "scopes": [
    "Biodiversity",
    "Compliance",
    "Habitat units"
  ],
  "aligns": [
    "Defra metric",
    "Statute (Environment Act 2021)"
  ],
  "roles": [
    {
      "id": "registry",
      "name": "Standard Registry",
      "permission": "Owns the policy, approves participants, anchors each issuance to its evidence."
    },
    {
      "id": "proponent",
      "name": "Project Proponent",
      "permission": "Registers the project and submits monitoring reports."
    },
    {
      "id": "vvb",
      "name": "Validation & Verification Body",
      "permission": "Independently validates the design and verifies monitored data."
    }
  ],
  "schemas": [
    "at://did:plc:bl0adl1sten1ngp0l1cyreg/org.broadlistening.policy.schema/uk-bng-bio-baseline",
    "at://did:plc:bl0adl1sten1ngp0l1cyreg/org.broadlistening.policy.schema/uk-bng-bio-monitoring"
  ],
  "graph": "at://did:plc:bl0adl1sten1ngp0l1cyreg/org.broadlistening.policy.graph/uk-bng",
  "issuesAs": "org.hypercerts.claim.activity",
  "workScope": "at://did:plc:bl0adl1sten1ngp0l1cyreg/org.hypercerts.workscope.cel/uk-bng-scope",
  "rights": "at://did:plc:bl0adl1sten1ngp0l1cyreg/org.hypercerts.claim.rights/uk-bng-rights",
  "createdAt": "2025-01-01T00:00:00.000Z"
}

04 · Schemas