Daylight and Sunlight Assessments in Barnet

If you are planning a new development or extension in the London Borough of Barnet, a daylight and sunlight assessment is often a key requirement for securing planning permission. Whether you are extending a period property in Finchley or Hendon, adding a side or rear extension in Edgware or Mill Hill, or proposing a new residential development in Colindale, Cricklewood or Chipping Barnet, your proposals may affect the daylight and sunlight enjoyed by neighbouring properties so Barnet's planning officers may 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 Barnet. Our reports are clear, technically robust, and written to support a smooth planning process.

When does Barnet require a daylight and sunlight assessment?

Not every application in Barnet 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
• Side and rear extensions or loft conversions in closely spaced terraced, semi-detached and suburban streets, 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.

Barnet's local planning policy

Barnet's approach to daylight and sunlight is guided by its Barnet Local Plan, adopted in March 2025. The Local Plan sets out the council's long-term vision and policies for development across the borough and forms the basis on which planning applications are determined. Its design and amenity policies require development to protect the amenity of neighbouring occupiers, including their access to daylight and sunlight, and daylight and sunlight assessments are expected for all applications where there is a potential significant adverse impact on the levels currently enjoyed by adjoining properties. In assessing the impact of development on natural light, Barnet applies the methodology set out in the BRE guidance document BR 209: Site layout planning for daylight and sunlight (2022 edition), the nationally recognised benchmark for daylight and sunlight assessments in the UK.

For householder applications such as extensions, conversions, roof alterations and loft conversions, Barnet's Residential Design Guidance SPD provides detailed supplementary guidance on how the council's policies should be applied to residential alterations and extensions. This SPD is a key reference point for schemes where the impact on neighbouring amenity, including natural light, is a consideration.

You can find Barnet's adopted Local Plan at barnet.gov.uk/planning-and-building-control/planning-policies-and-local-planand the borough's residential design guidance at barnet.gov.uk/planning-and-building/planning-policies-and-local-plan/local-plan/design-guidance.

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 Barnet report includes

Our daylight and sunlight assessments for Barnet 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 Barnet.

Get in touch

If you are planning a development in Barnet 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.