Which proposals may need assessment?
Westminster's 2026 validation list identifies external and floodlighting, illuminated building features and certain illuminated signs as relevant examples. National guidance also requires consideration where a new development would be sensitive to existing light, or where lighting could affect protected species or an intrinsically dark setting. [2] [1]
A small installation may need only proportionate information, while a larger or sensitive scheme can require a detailed assessment. Policy DM2 of the NPPF published on 17 August 2026 supports information that is relevant and necessary for the planning decision. [3]
What does the report need to explain?
National guidance organises the issue around where the light shines, when it operates, how much light is produced and its ecological effects. It distinguishes useful illumination from unwanted spill, glare and brightening of the night sky. [1]
Ask the designer to identify the intended purpose of each part of the scheme. Then request drawings and technical information that show how the proposed fittings, their positions and their controls achieve that purpose without unnecessary effects elsewhere. The final report should make it possible to identify the equipment and settings being assessed.
A practical submission checklist is:
- Locate the proposed lights and the places or features that could be affected.
- Explain the assessment criteria and the site's sensitivity.
- Demonstrate the proposed performance and identify mitigation.
- Record the operating controls and any installation assumptions.
This is a suggested way to organise the information, not a universal statutory form.
Who prepares it?
Use someone with relevant external-lighting design and assessment experience. Where ecology is involved, coordinate the lighting designer's work with an ecologist rather than assuming that a scheme acceptable for neighbours is automatically suitable for wildlife. Government guidance expressly identifies ecological effects as a separate consideration. [1]
Natural England's bat guidance explains that development affecting bats may need survey, mitigation and licensing consideration. The lighting assessment should use the relevant ecological findings, including important habitat features, rather than treating a generic product description as evidence that no effect is possible. [4]
Can controls reduce the impact?
National guidance identifies switching off, dimming and restricting lighting to times when it is needed as possible ways to reduce effects. It also emphasises careful positioning and selection of the lighting equipment. These are design options to assess for the particular site, not a fixed curfew that applies throughout England. [1]
Before installation, pass the agreed layout and control requirements to the installer. Ask the designer to review substitutions or altered aiming positions, and retain the information needed to maintain the assessed arrangement. A planning drawing showing only a symbol for “external light” may not record the commitments on which the assessment depended.