Glossary
BRE 209: the daylight and sunlight test London uses
The standard methodology for daylight and sunlight assessment in planning.
The standard methodology for daylight and sunlight assessment in planning.
BR 209 is the BRE report Site Layout Planning for Daylight and Sunlight: A Guide to Good Practice. It is the standard London planning officers use to judge whether a proposal harms a neighbour's light. Its main tests are the 25-degree rule, vertical sky component, no-sky line and annual probable sunlight hours.
Vertical sky component is the headline test: a neighbouring window retaining at least 27% VSC, or at least 0.8 times its former value, is normally considered adequately lit. The no-sky line test asks that no more than 20% of a room's working plane loses its view of the sky.
For sunlight, a window facing within 90 degrees of due south should retain at least 25% of annual probable sunlight hours, of which at least 5% falls in the winter months, or at least 0.8 times the former value.
For a single-storey rear extension it rarely is: the 45-degree and 25-degree rules in the borough's own design guidance usually settle it. A daylight and sunlight report becomes necessary for two-storey and multi-storey schemes, for anything close to a boundary with habitable windows, and whenever a neighbour objects on light grounds.
BR 209 is guidance, not law. Officers apply it flexibly in dense urban contexts, and the current edition is explicit that the numerical targets are not to be applied rigidly where existing density already suppresses them.
BR 209 is a planning matter, assessed by the council. A right to light is a private legal easement, usually acquired after 20 years of uninterrupted enjoyment, and enforced through the courts. Planning permission is no defence to an injunction.
BR 209 (daylight and sunlight guidance) in a Harrow context: London Borough of Harrow (Harrow Council) runs 29 conservation areas including the Harrow on the Hill Conservation Area and the Pinner Village Conservation Area, and there is no borough-wide Article 4 direction, so permitted development generally survives outside conservation areas. That decides how br 209 (daylight and sunlight guidance) is handled: £548 and 8 weeks for a Harrow householder application, or £274 for the Lawful Development Certificate that records br 209 (daylight and sunlight guidance) as lawful. The law behind br 209 (daylight and sunlight guidance) sits in the Town and Country Planning Act 1990, the GPDO 2015 and the Building Regulations 2010.
| Full title | BRE Site Layout Planning for Daylight and Sunlight |
|---|---|
| Vertical sky component target | 27%, or 0.8× former value |
| No-sky line test | No more than 20% of working plane loses sky view |
| Annual probable sunlight hours | 25% annual, 5% winter, or 0.8× former |
| Status | Guidance, not statute |
| Typical trigger | Two-storey or taller schemes near habitable windows |
No. It is best-practice guidance that planning authorities adopt through their local policies.
A daylight and sunlight consultant, using 3D modelling of the existing and proposed situation.
No. They are separate tests under separate law.
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