Case A: 4-home rural infill, 0.6 ha, lowland modified grassland
- PEA + UKHab baseline: £1,800
- Metric output: 2.88 baseline BU; delta 3.17 BU after 10% uplift assuming no on-site retention.
- On-site delivery via species-rich grassland creation: £28k incl 30-yr management.
- Off-site purchase at medium distinctiveness: £82k (3.17 BU x £26k mid-rate).
- Statutory credits (effective): £266k.
- S106 legal: £3,500.
- Chosen route: on-site. Total cost: £33,300.
Case B: 50-home greenfield, 2.4 ha, mixed habitat
- PEA + UKHab + Phase 2 bat survey: £5,200
- Metric output: 14.4 baseline BU; delta 15.84 BU after 10% uplift.
- On-site delivery infeasible at scale; SUDS pond integration delivers 3 BU.
- Off-site purchase: 12.84 BU at £32k mid-rate = £411k.
- S106 legal: £6,200; 30-yr management bundled into off-site price.
- Chosen route: hybrid on-site (3 BU) + off-site (12.84 BU). Total cost: £423k.
Case C: brownfield mixed-use, 1.1 ha, post-industrial habitat
- PEA + invertebrate survey: £3,800 (post-industrial habitats can carry priority status).
- Metric output: 6.6 baseline BU at medium distinctiveness; delta 7.26 BU.
- On-site delivery via brownfield-targeted habitat creation: £95k.
- Off-site purchase: £232k.
- S106 legal: £4,100.
- Chosen route: on-site. Total cost: £102,900. Brownfield exemption consultation may further reduce future cost.