Daylight and Sunlight Assessments in Kingston upon Thames

Protecting a neighbour's access to light is a common concern in the Royal Borough of Kingston upon Thames, and a well-prepared daylight and sunlight assessment can be central to obtaining planning permission. Whether you are extending a family home in Surbiton or New Malden, altering a property in Kingston town centre or Norbiton, or bringing forward a larger residential scheme in Tolworth, Chessington or Berrylands, the effect of your proposals on nearby homes is likely to be examined and demonstrating that any loss of light is reasonable falls to the applicant.

At Sunlight Assessments, we prepare BRE-compliant daylight and sunlight assessments for planning applications across the Royal Borough of Kingston upon Thames. Our reports are clear, technically robust, and written around the specific policy tests Kingston uses to determine applications.

When is an assessment needed in Kingston?

Not every application requires a formal study, but one is commonly expected where:

• 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
• Side and rear extensions or loft conversions in tightly built Victorian and Edwardian terraces, where neighbouring windows may be particularly close to the proposed works
• 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.

Kingston's planning policy in detail

Kingston determines applications against its adopted Core Strategy (adopted 2012) and the Kingston Town Centre Area Action Plan (2008), read together with the Mayor's London Plan. The council has been preparing a new borough-wide Local Plan to replace these documents, but until it is formally adopted the Core Strategy remains the statutory basis for decisions. Its design and amenity policies require development to protect the living conditions of neighbouring occupiers, including their access to daylight, sunlight and outlook, and to avoid an overbearing or overshadowing relationship with adjoining homes.

In practice, Kingston applies a '45 degree rule' as a working guide when judging the impact of a new building or extension on a neighbour's light. The test looks at whether the proposal breaches a 45-degree line taken in relation to a neighbour's habitable-room windows, and is used to help maintain satisfactory relationships between buildings, prevent an overbearing impact, and avoid excessive loss of daylight or overshadowing of habitable rooms and amenity spaces. Where a proposal fails or is marginal against this rule of thumb, the council will expect the light impact to be examined more fully - through a daylight and sunlight assessment. For more information on the 45 degree rule please read our blog.

The detailed householder guidance sits in Kingston's Residential Design SPD, which supplements the Core Strategy and sets out the council's expectations for both new residential development and extensions or alterations to existing homes. This SPD is the practical reference point for anyone extending or altering a property in the borough, and is read alongside the adopted development plan.

For the numerical assessment, Kingston relies on the Building Research Establishment's guidance, BR 209: Site layout planning for daylight and sunlight (2022 edition), the nationally recognised benchmark. An extension in Kingston is therefore often considered both against the borough's 45-degree rule and, where warranted, the BRE metrics of VSC, NSL and APSH.

You can review Kingston's Local Plan and Core Strategy at kingston.gov.uk/planning-and-building-control/planning-policy/local-plan and the Residential Design SPD at kingston.gov.uk/planning-and-building-control/planning-policy/supplementary-planning-documents/residential-design.

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 Kingston report includes

Our daylight and sunlight assessments for Kingston 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 Royal Borough of Kingston upon Thames.

Get in touch

If you are planning a development in Kingston 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 turn around a report within 5 working days of receiving the necessary information.