Understanding daylight requirements in East Dunbartonshire is essential for anyone planning a house extension, a loft conversion, a new dwelling or a flatted development across Bearsden, Milngavie, Kirkintilloch, Bishopbriggs, Torrance or Lenzie. East Dunbartonshire Council is the planning authority for the area, and it assesses how a proposal affects the daylight, sunlight and privacy of neighbouring homes using a clear set of tests set out in its adopted development plan and supporting guidance. This article explains how those requirements work in practice and how a professional daylight and sunlight report can support your application.
The planning framework in East Dunbartonshire
Planning decisions in East Dunbartonshire are made against the statutory development plan. This has two parts. The first is National Planning Framework 4 (NPF4), adopted by the Scottish Government in February 2023, which is now part of the statutory development plan for the whole of Scotland. The second is the council's own East Dunbartonshire Local Development Plan 2 (LDP2), which was adopted in 2022 and superseded the previous Local Development Plan of 2017.
Two policy strands are most relevant to daylight and amenity:
- NPF4 Policy 14 (Design, quality and place) and Policy 16 (Quality homes), which require development to create well-designed, sustainable places and to provide good-quality residential amenity, including adequate levels of daylight and sunlight.
- LDP2 Policy 10 (Design and Placemaking), which requires new development to be of a high standard of design and to protect the amenity of existing and future occupiers. LDP2 Policy 1 sets out the wider development strategy that this design policy supports.
Like most Scottish councils, East Dunbartonshire does not set its own bespoke numerical daylight metric in the LDP itself. Instead, the detailed daylight and sunlight methodology comes from nationally recognised best practice, applied to support the amenity and design aims of LDP2 and NPF4.
The Design and Placemaking Supplementary Guidance
The most important document for daylight in East Dunbartonshire is the council's Design and Placemaking Supplementary Guidance (2022). Supplementary guidance in Scotland is statutory: it forms part of the development plan and carries weight in decision making, in line with Scottish Government Circular 6/2013. The guidance supports LDP2 Policy 10 and provides the practical detail that planners apply when assessing an application.
Section 15.3 of the guidance, headed Daylight and Sunlight, sets out the council's tests directly. It explains that it is the responsibility of the council to protect the privacy and amenity of all residents, that a reasonable amount of daylight should reach the windows of residential properties, and that appropriate sunlight levels should be available in the principal living room of a home. Importantly, the guidance states explicitly that the conventional daylight and sunlight tests used in planning are those set out in the Building Research Establishment (BRE) guide, Digest 209, ‘Site Layout Planning for Daylight and Sunlight: A Guide to Good Practice’.
The 25 degree test
The first rule of thumb the council uses is the 25 degree test. If an obstructing building, such as a new extension or a neighbouring development, creates an angle of greater than 25 degrees from the horizontal when measured from the centre of the lowest affected window, then daylight may be at risk and a more detailed study is required. As the guidance notes, exceeding the 25 degree angle does not automatically mean daylight will fall below standard. Where it is exceeded, light levels are checked using the BRE's detailed tests, including:
- Daylight distribution
- Average daylight factor
- Annual probable sunlight hours
The 45 degree test
The second rule of thumb is the 45 degree test, used to check the impact of extensions built at 90 degrees to a neighbour's window. If the centre of the affected window lies on the extension side of both 45 degree lines, measured on plan and on elevation, then poor daylighting conditions are likely to exist. The guidance also warns about the so-called ‘tunnel effect’, where a proposal might technically meet the 45 degree test but still cause an unacceptable loss of light. This is a common issue for rear and side extensions in the closely spaced terraces and semis found across Kirkintilloch and Bishopbriggs.
Privacy and window-to-window distances
East Dunbartonshire also applies clear privacy standards, set out under section 17.2.7 (Privacy and Light) of the guidance. The headline figure is that windows of habitable rooms which directly face each other should be positioned at least 18 metres apart. The guidance also includes a table of minimum window-to-window distances that vary with the angle between the windows, with a minimum of around 9 metres where windows are set at a wide angle to one another rather than directly facing. These privacy distances sit alongside the daylight tests and are assessed together.
For garden and amenity space, the guidance looks for a minimum of 40 square metres of private garden ground for non-terraced properties and a usable rear garden depth that protects privacy. Rear extensions are also expected to respect limits on how far they project down a shared boundary, to avoid overshadowing and overbearing impacts on neighbours.
What this means for your project
Whether you are extending a villa in Bearsden, building a new home in Milngavie or developing flats in Kirkintilloch town centre, the council will want to see that your proposal respects both the daylight tests and the 18 metre privacy distance. A daylight and sunlight assessment is most often requested where:
- An extension or new building exceeds the 25 degree line from a neighbour's window;
- A new dwelling or flatted block sits close to existing homes;
- Windows of new and existing habitable rooms would face each other at less than 18 metres;
- A planning officer or objector raises overshadowing, overlooking or loss of light as a concern.
Producing a clear, BRE-based report at the application stage can help an officer reach a positive recommendation and can address neighbour objections with objective evidence rather than assertion.
How Fortress Associates can help
Fortress Associates provides a professional daylight and sunlight report service prepared to BRE BR 209 (2022) and BS EN 17037, the recognised best-practice methodology that East Dunbartonshire applies in support of its LDP2 and NPF4 design and amenity policies. We assess the 25 and 45 degree tests, run the detailed BRE daylight and sunlight calculations where needed, and check window-to-window privacy distances so your application is supported by clear evidence. We work UK-wide with a turnaround of 4 to 5 working days and no advance payment. We also prepare building warrant and Building (Scotland) Regulations drawings. To discuss your project in Bearsden, Milngavie or Kirkintilloch, please get in touch.
Sources & further reading
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