Summary
Daylight and sunlight checks help assess whether a proposed development could unacceptably reduce natural light to neighbouring homes, gardens or proposed new rooms. Buyers should look for these issues where a nearby scheme adds height, depth or mass close to boundaries, especially where it could affect main living rooms, bedrooms, kitchens or amenity space.
BRE 209 is widely used as a daylight and sunlight guide in planning assessments. It is guidance rather than a rigid legal pass or fail rule, so local planning authorities still apply judgement based on site context, urban density, policy and design quality. A buyer should not treat the presence of a BRE report as automatic proof that there is no impact. They should read what windows, rooms and gardens were tested, what assumptions were used and whether any reductions are described as acceptable in context.
Definition
Daylight and sunlight assessment is the planning review of how a development affects access to natural light within buildings and open spaces. BRE 209 is a recognised good practice guide used to assess daylight and sunlight effects, but it is applied with planning judgement rather than as a simple automatic threshold.