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BRE DAYLIGHT & SUNLIGHT TESTS - BUILDINGS & OUTSIDE AREAS

 

Local Authority Planning Departments are able to request a developer to provide an assessment of Daylight and Sunlight as part of the planning application.  This provides a definitive assessment of the impact of a proposed development upon neighbouring buildings and land in respect of sunlight and daylight.

At this stage, it should be noted that the BRE Daylight and Sunlight Tests are completely separate from the Legal Right to Light which uses different parameters to assess the acceptability of light implications on a neighbouring property.  Even though, in many circumstances, satisfactory results for the BRE tests will probably also mean satisfactory conclusions with regards to Legal Right to Light assessments, this is not always the case and both need to be considered separately.

The normal assessment method for Daylight and Sunlight tests in respect of applications for planning permission uses ‘BRE digest 209: Site Layout Planning for Daylight and Sunlight’.

Essentially, the tests described within this document have three main considerations with regards to assessing the acceptability of any effects of a development upon the daylight and sunlight to neighbouring buildings and certain external areas.  These are: Diffuse daylight to windows, direct sunlight to windows and direct sunlight to certain open areas and gardens.  The various aspects of these are discussed in more detail below.  Beneath that is BRE guidance as to when a Local Authority should request Daylight and Sunlight Tests.

DIFFUSE DAYLIGHT TO A WINDOW  

As for the Legal Right to Light, this takes no account of direct sunlight and assesses only the amount of diffuse light to an affected window. The principal measure is called the Vertical Sky Component which assesses the amount of sky visible at a wall containing a window. However, there is a more detailed assessment called Average Daylight Factor which also takes account of the room dimensions, internal finishes and the transmittance of the glazing in the window. 

DIRECT SUNLIGHT TO A WINDOW

 

This test considers the hours of sunlight a window will receive over a 12 month period.  Because the test relates only to sunlight, only windows facing within 90 degrees of due south are considered under the BRE 209 methodology.

The guidance is that main windows should receive at least 25% of the ‘total probable sunlight hours’ for a 12 month period.  This should include 5% of the total probable sunlight hours over the winter months between 21 September and 21 March.

SUNLIGHT TO EXTERNAL AREAS

The BRE guidance suggests that consideration of sunlight to external areas should normally include: 

  • Gardens, usually the main back garden of a house, and allotments;

  • Parks and playing fields;

  • Children’s playgrounds;

  • Outdoor swimming pools and paddling pools;

  • Sitting-out areas, such as those between non-domestic buildings and in public spaces;

  • Focal points for views, such as a group of monuments or fountains.

The BRE guide recommends that, at a maximum, no more than 40% of the external area should be prevented from receiving any sunlight at all on 21 March.  However, ideally, this figure should be not more than 25% of the area in permanent shadow.

SHADOW PATH ANALYSIS DRAWINGS

Although not part of the formal tests within BRE209, this document does contain reference to this analysis and it is sometimes requested by Planning Authorities. 

WHEN SHOULD A COUNCIL ASK FOR THE BRE DAYLIGHT & SUNLIGHT TESTS?

 

The BRE Sunlight and Daylight Tests can be applied to: 

  • Proposed new buildings to confirm whether the proposed building and external spaces would receive adequate daylight and sunlight;

  • Existing buildings and external spaces which would be affected by a proposed development, or

  • Existing potential development land which might be affected by a proposed development on a neighbouring site.

The BRE guidance contains various basic tests which use the application of angled lines onto a section drawing through the development to make an initial assessment to determine whether a further more detailed full assessment is necessary. Such further consideration would be by means of the BRE Daylight and Sunlight Tests using full 3D computer modelling to make an accurate assessment of the necessary tests.

For guidance regarding the possible need for Daylight and Sunlight assessments, please do not hesitate to speak to us.

SERVICES OFFERED BY SMITH MARSTON LLP:

At Smith Marston LLP, we use sophisticated computer software and 3D CAD modelling to undertake the tests recommended in BRE 209, including modelling techniques to track the path of the sun in order to be able to assess matters in relation to direct sunlight.

Such BRE Daylight and Sunlight assessments can be necessary to satisfy a request (or an anticipated request) from a planning authority. Alternatively, the BRE Daylight and Sunlight tests and our associated report can be useful in the following circumstances:

  • To support an objection to an application for planning permission even if the planning authority had not requested BRE Daylight and Sunlight tests from the developer.
  • To support an Appeal against refusal of planning permission if a reason for refusal was an unjustified subjective consideration that the development would adversely affect daylight and sunlight to other neighbouring properties.
  • To assist with amending a design proposal to satisfy the BRE Daylight and Sunlight tests for a re-application following a legitimate refusal of planning permission due to daylight and sunlight matters.

We can also advise a developer on daylight and sunlight assessment at an early design stage with regards to other related matters such as site planning. This can be helpful to maximise the use of a site whilst avoiding issues relating to the BRE Daylight and Sunlight tests plus minimising the risk of any legal rights to light claims from neighbours. We are also able to advise regarding site layouts in respect of optimising the use of sunlight to create comfortable and environmentally-friendly buildings, including making best use of 'solar gain' heating to reduce energy consumption.

CONTACT US

For an initial free consultation regarding any matters relating to Daylight and Sunlight Assessments, please contact Philip Smith or Adrian Marston of Smith Marston LLP.

Smith Marston LLP work in association with Rights of Light Consulting, another specialist consultancy in the field of rights of light who cover the South of England.  This allows us to provide national coverage, offering consistency of advice and reporting format for clients who have national requirements or portfolios.

      

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