If you are planning a house extension, a loft or dormer conversion, or a new residential development in Giffnock, Newton Mearns, Barrhead, Clarkston or Busby, understanding the daylight requirements in East Renfrewshire will help your application run smoothly. East Renfrewshire Council is the planning authority for the area, and a key part of its assessment is how a proposal affects the daylight, sunlight and privacy of neighbouring homes. Helpfully, East Renfrewshire is one of the few Scottish councils to publish its own dedicated daylight and sunlight guidance, which sets out the tests it uses in plain terms.
The planning framework in East Renfrewshire
Planning applications in East Renfrewshire are decided against the statutory development plan, which is made up of two parts. The first is National Planning Framework 4 (NPF4), adopted by the Scottish Government in February 2023 and now part of the statutory development plan throughout Scotland. The second is the East Renfrewshire Local Development Plan 2 (LDP2), which was adopted on 31 March 2022 and guides development across the area to 2031.
The policies most relevant to daylight and amenity are:
- NPF4 Policy 14 (Design, quality and place) and Policy 16 (Quality homes), which require new development to be well designed and to deliver good residential amenity, including adequate daylight and sunlight.
- LDP2 Policy D1 (Placemaking and Design), which states that development should not result in a significant loss of character or amenity, and that the amenity of neighbouring residents must be protected, including by not unreasonably restricting their sunlight or privacy.
- LDP2 Policy D1.1 (Extensions and alterations to existing buildings for residential purposes), which applies specifically to householder proposals such as extensions, dormers and garages.
Both Policy D1 and Policy D1.1 expressly direct applicants to the council's supporting guidance on daylight and sunlight, which is where the practical tests are found.
The council's Daylight and Sunlight Design Guide
East Renfrewshire's Daylight and Sunlight Design Guide Supplementary Guidance exists to help assess applications and to give general advice on daylight and sunlight in new development. It is based on the empirical guidelines and methods of the Building Research Establishment (BRE) guide, ‘Site Layout Planning for Daylight and Sunlight: A Guide to Good Practice’. The guide is clear that all buildings should have adequate levels of daylight, that this should be a priority for new development, and that some sunlight to main inhabited rooms is also important. It sets out two practical tests.
The 45 degree approach
The first test the council uses to judge the impact on a neighbour is the 45 degree approach. Its purpose is to make sure that a development does not take away too much daylight from a neighbouring window. A line is drawn at a 45 degree angle from the centre of the affected window, on both plan and elevation. The guide notes that a loss of daylight may occur where a development lies within 12 metres of the neighbouring window and falls inside the 45 degree lines. This test is especially relevant to the rear and side extensions that are common across the suburban streets of Giffnock, Clarkston and Newton Mearns.
The 25 degree approach
The second test is the 25 degree approach, used where a building faces an affected window. Suitable daylight for habitable rooms is achieved when a 25 degree angle, taken from the centre of the lowest affected window, is kept clear and unobstructed by the new building. The guide explains that where the property opposite has a high ridge, the loss of daylight will be more notable than where the building has a lower ridge height. If a proposed extension fails the test, the council expects further investigation and supporting evidence.
Householder rules that interact with daylight
East Renfrewshire's Householder Design Guide sits alongside the daylight guidance and contains several dimensional rules that directly affect overshadowing and overlooking. Notable points include:
- Direct overlooking and excessive overshadowing of neighbouring properties should be avoided.
- Single-storey rear extensions, including conservatories, should not generally extend more than 4 metres down a common rear boundary.
- No more than 50% of the rear garden should be occupied by the extension, so that useable private garden ground is retained.
- Two-storey rear extensions should normally be set back a minimum of 2 metres from a common boundary.
- Porches should not project more than 1.5 metres from the front elevation.
These limits work together with the 25 and 45 degree daylight tests, and a proposal that respects the dimensional rules will usually find it easier to demonstrate acceptable daylight and privacy.
What this means for your project
A formal daylight and sunlight assessment is most often needed in East Renfrewshire where:
- An extension or new building lies within 12 metres of, and inside the 45 degree lines of, a neighbour's window;
- A new building breaches the 25 degree angle to an existing habitable room;
- A new house or flatted development sits close to existing homes;
- A planning officer or neighbour raises overshadowing or loss of light.
For new homes, BS EN 17037 provides target daylight levels for habitable rooms and recommendations on sunlight, which is increasingly relevant to the higher-density and flatted schemes coming forward in Barrhead and Newton Mearns. Submitting a clear, BRE-based report with your application gives the case officer objective evidence and helps resolve neighbour concerns with measurements 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 underpins East Renfrewshire's own Daylight and Sunlight Design Guide and supports LDP2 Policy D1 and NPF4. We assess the council's 25 and 45 degree approaches, run the detailed BRE daylight and sunlight calculations where required, and check privacy and overlooking so your submission is backed by clear evidence. We work UK-wide with a turnaround of 4 to 5 working days and no advance payment, and we also prepare building warrant and Building (Scotland) Regulations drawings. To discuss a project in Giffnock, Newton Mearns or Barrhead, please get in touch.
Sources & further reading
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