Daylight and Sunlight Assessments in Lambeth

If you are planning a new development or extension in the London Borough of Lambeth, a daylight and sunlight assessment is often a key requirement for securing planning permission. Whether you are extending a period property in Balham or Streatham, adding storeys to a commercial building in Brixton, or proposing a new residential development near Clapham or Vauxhall, your proposals may affect the daylight and sunlight enjoyed by neighbouring properties — and Lambeth's planning officers will expect you to demonstrate that any impacts are acceptable.

At Sunlight Assessments, we prepare BRE-compliant daylight and sunlight assessments for planning applications across the London Borough of Lambeth. Our reports are clear, technically robust, and written to support a smooth planning process.

When does Lambeth require a daylight and Sunlight Assessment?

Not every application in Lambeth will require a formal assessment, but there are common scenarios where one is expected:

• Extensions that extend close to a boundary with a neighbouring property, particularly where habitable rooms face the affected elevation
• New residential developments where neighbouring properties may lose access to natural light
• Applications where the Local Planning Authority has identified daylight and sunlight as a material planning consideration
• Loft conversions or rear extensions in tightly built Victorian and Edwardian terraces, where the proximity of neighbouring windows can make impacts particularly sensitive
• Conversions and changes of use where new habitable rooms are proposed

If you are unsure whether your scheme requires an assessment, we are happy to advise on this at no cost.

Lambeth's local planning policy

Lambeth's approach to daylight and sunlight is set out in its Lambeth Local Plan 2021, which covers the period 2020 to 2035 and was adopted in September 2021. The Local Plan sets out the council's policies for all types of development across the borough and forms the basis on which planning applications are determined. In assessing the impact of development on natural light, Lambeth applies the methodology set out in the BRE guidance document BR 209: Site layout planning for daylight and sunlight (2022 edition), which provides the nationally recognised benchmark for daylight and sunlight assessments in the UK.

For detailed design guidance, Lambeth's Design Guide SPD (adopted August 2023) provides supplementary guidance across five parts. Part 4 — Building Alterations, Extensions and Retrofit — is directly relevant to householder applications such as loft conversions, rear extensions, and other alterations, and sets out Lambeth's expectations around the impact of built form on amenity, including natural light. Part 2 — Advice for All Developments — contains broader design principles that apply across all development types.

You can find the Lambeth Local Plan at lambeth.gov.uk/planning-building-control/planning-policy-guidance/lambeth-local-plan-2021 and the Design Guide SPD at lambeth.gov.uk/planning-building-control/planning-policy-guidance/supplementary-planning-documents-other-policy-guidance/supplementary-planning-documents-spds.

How the assessment works

We use the methodology set out in BRE BR 209 to assess the impact of proposed development on daylight and sunlight. The key tests we carry out include:

Vertical Sky Component (VSC): This measures the amount of sky visible from the centre of a window. BRE guidance recommends that a VSC of 27% or more is generally considered adequate. Where a development results in a VSC that is less than 0.8 times its former value, the reduction may be noticeable to occupants.

No-Sky Line (NSL): This assesses the distribution of daylight within a room by plotting the line beyond which no sky is visible. Where the area of a room that can receive direct skylight is reduced by more than 20%, occupants are likely to notice a deterioration in the quality of daylight.

Annual Probable Sunlight Hours (APSH): This test is used to assess access to sunlight for windows that face within 90° of due south. It considers both the winter and annual totals to determine whether sunlight losses are likely to be material.

Where appropriate, we also carry out sun-on-ground studies to assess the impact on garden or amenity spaces.

What our Lambeth report includes

Our daylight and sunlight assessments for Lambeth planning applications typically include:

• A clear description of the proposed development and the surrounding context
• Identification of all relevant neighbouring windows and amenity spaces
• VSC and NSL calculations for affected neighbouring properties
• APSH calculations where required
• A comparison of results against BRE BR 209 benchmarks
• A professional assessment of whether any identified impacts are likely to be considered material in planning terms
• Recommendations for design amendments where required, to help reduce impacts and support approval

All reports are produced by qualified consultants with experience of working across the London Borough of Lambeth.

Our local experience in Lambeth

We have extensive experience preparing daylight and sunlight assessments across London and understand the challenges of designing within a dense urban environment. A recent example of our work in Lambeth is a neighbours impact assessment we carried out for an approved application at 55 Cambray Road, SW12 0ER, a loft conversion involving an L-shape mansard roof extension and the installation of two front rooflights. Our assessment provided the clear evidence base the applicant needed to demonstrate that impacts on the neighbouring properties remained within acceptable limits under BRE BR 209. You can view the planning record here.

We are familiar with Lambeth's planning requirements and provide clear, practical advice to help identify potential issues early in the design process and support a smoother planning application.

Get in touch

If you are planning a development in Lambeth and would like to discuss whether you need a daylight and sunlight assessment, please get in touch. We offer a free initial consultation and can usually turn around a report within 5 working days of receiving the necessary information.