Updated 20 September 2026
Glossary
These terms are the ones this site relies on. Definitions follow statute, the NPPF, Planning Practice Guidance and the brownfield data standard. Where a common campaign phrase is looser than the official term, the official term wins.
Brownfield land register
A statutory list each English local planning authority must keep of previously developed land that is suitable, available and achievable for housing. Part 1 is mandatory. Part 2, permission in principle, is optional.
Previously developed land
Land which is or was occupied by a permanent structure, including the curtilage, with listed exceptions such as agriculture, forestry and some minerals land. This is the NPPF definition the register uses.
Minimum net dwellings
The lowest estimate of additional homes a register site is assessed to support. CPRE and this site use it as the conservative capacity figure.
Standard method
The national formula in Planning Practice Guidance that produces an advisory local housing-need starting point. It is not by itself a plan target.
Flood Zone 3
Land with a high probability of flooding, split into Zone 3a and Zone 3b (functional floodplain). New dwellings are not appropriate in Zone 3b.
Nutrient neutrality
A legal requirement, following Natural England advice, that additional overnight accommodation in named catchments must not increase nutrient loads to protected sites, usually by buying or building mitigation.
Biodiversity net gain
A statutory condition that most major development must deliver at least 10% measurable gain in biodiversity units, secured for at least 30 years, preferably on site.
Residual land value
What is left for the land after subtracting build costs, abnormals, policy contributions and profit from the value of the completed scheme. If it falls below the price at which the owner will sell, the site does not come forward.
Abnormal costs
Site-specific extra costs, especially demolition, contamination, ground gas, flood works and unusual foundations. The HCA 2015 guidance is the usual official reference.
Workable capacity
This site's phrase for the register dwellings still standing after every published discount has been applied in turn: no permission, flood, nutrient catchment, ground to clean, unclear ownership, Green Belt, too tight for net gain, and still in employment use. Each site is counted out once, at the first reason that stops it.
It is an illustrative screen, not a five-year housing land supply figure, and it is still paper: a site survives the screen by not having a recorded reason to fail, which is not the same as somebody building it.
Questions people ask
- Is previously developed land the same as brownfield?
- In everyday use, yes. In policy, previously developed land is the NPPF term. The 2017 regulations use that definition for the register.
Where the numbers come from
- Town and Country Planning (Brownfield Land Register) Regulations 2017 — legislation.gov.uk, 16 April 2017
- Brownfield land registers data standard — GOV.UK, 31 October 2019
- Planning Practice Guidance: housing and economic needs assessment — Ministry of Housing, Communities and Local Government, 12 December 2024. Standard method as revised under the December 2024 NPPF. Figures here use a May 2026 compilation of that method.
- Planning Practice Guidance: biodiversity net gain — Department for Environment, Food and Rural Affairs / MHCLG, 12 February 2024. 10% biodiversity net gain became mandatory for major development in February 2024.
- Nutrient neutrality advice to competent authorities — Natural England, 16 March 2022. Covers the River Wensum SAC and Broads SAC/Ramsar catchments, affecting all seven Norfolk local planning authorities.
- Flood Map for Planning (Flood Zones 2 and 3) — Environment Agency, 1 January 2026. Open Government Licence. Used here as context, not as a site-by-site intersection in version 1.