Glossary – Page 3
Substantive definitions of planning terms with their policy source and a worked example.
Glossary articles – page 3
479 articlesSource protection zone 1 and what it restricts
The inner source protection zone is a 50 day travel time to a drinking water abstraction. Inside it, infiltration drainage and several below-ground activities are resisted.
Veteran trees and their buffer zones
A veteran tree carries unusual value through its age, size or condition. Policy treats it as irreplaceable habitat, and the buffer is usually larger than a standard root protection area.
Rating level under BS 4142, explained for reviewers
The rating level is the specific sound level plus corrections for tonality, impulsivity and intermittency. How each part is derived, and what a reviewer should challenge in a plant noise assessment.
Volumetric run-off coefficient in drainage design
The coefficient converts rainfall depth into run-off volume, and volume is a different question from peak rate. Confusing the two produces a system that passes the discharge check and floods anyway.
The Whitley principle and unlawful implementation
Work carried out in breach of a true condition precedent is not carried out under the permission at all. The risk is not enforcement, it is a permission that was never lawfully begun and has since expired.
Pollutant linkage: what it means for contaminated land
Contaminated land decisions turn on whether a source, a pathway and a receptor are actually connected. Here is how that chain is tested, broken and verified in a planning application.
Upfront carbon in modules A1 to A5
Upfront carbon covers the product stage, transport to site and construction process, all emitted before occupation. What each module includes, which data counts, and why module D stays out of the total.
Fabric energy efficiency standard in an energy statement
The fabric energy efficiency standard measures space heating and cooling demand from the building shell alone. Here is how the Part L target is set, which design moves shift it, and what an energy statement should report.
Overheating criteria under CIBSE TM59
TM59 has two criteria and both must pass. The bedroom test of 26 degrees for no more than 32 hours is the one that usually fails, and the one that drives the design.
Internal noise guideline values in BS 8233
The BS 8233 internal ambient noise values are easy to quote and easy to misapply. The open window assumption underneath them is where most assessments are challenged.
Critical duration storm and attenuation volume
Attenuation storage is sized from the storm duration that needs the most volume, not from a single design event. How the critical duration is found and what a drainage strategy has to show.
Percolation test for a foul drainage field
The Vp value from a percolation test sets the drainage field area. A result below 15 or above 100 seconds per millimetre rules a field out whatever the layout.
Blockage scenario in a surface water drainage design
A blockage scenario asks where the water goes when the flow control silts up. It is a sensitivity test, not a design event, and it usually costs a weir level rather than a bigger basin.
Flood hazard rating and the depth velocity product
Flood hazard rating combines depth, velocity and a debris factor into one number with four bands. The debris factor step is what pushes a shallow urban route into the danger for most band.
Pepper-potting and cluster limits in affordable housing
Pepper-potting disperses affordable homes across a scheme so tenure is not legible from the street. Cluster limits are the compromise that keeps a registered provider at the table.
Nomination agreement with a registered provider
A nomination agreement decides who moves into affordable rented homes. It is a housing document, not a planning one, and it often sits on the critical path.
Curtilage of a listed building and how it is determined
Curtilage is a question of fact, not a line on a map. Here are the three factors the courts apply, the 1948 test for ancillary structures, and how to get certainty.
Searching the Historic Environment Record
An HER search is the archaeological baseline for most applications. Here is how to request one, what the records mean, and what the search cannot tell you.
Scheduled monument consent and who decides it
Works to a scheduled monument need consent from the Secretary of State, not the council. Here is what counts as works, where class consents help, and what the pack contains.
The Wheatcroft principle on amended plans
Amended plans can be accepted mid-determination only if the change would not deprive consultees of the chance to comment. Here is how that test is applied, and what to do when it is borderline.
Veteran tree features and the planning consequences
Veteran status comes from decay and habitat features rather than age. It makes a tree irreplaceable habitat, with a 15 times stem diameter buffer and a very narrow policy test.
Fallback position in planning and the real prospect test
A fallback position argues that refusing the application leads to something else lawful being built instead. The test is a real prospect of implementation, and the weight depends on the evidence.
Benchmark land value in a viability appraisal
Benchmark land value is the figure a viability appraisal is tested against. It starts from existing use value plus a reasoned premium, and the price paid for the site is not the starting point.
Irreplaceable habitat: what it means in planning
Irreplaceable habitat is a defined list, not a judgement. A scheme affecting it cannot be fixed by buying biodiversity units; it either avoids the habitat or fails.
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