Whether you are extending a house in Welwyn Garden City, building new homes in Hatfield, or bringing forward a larger scheme elsewhere in the borough, understanding the daylight requirements in Welwyn Hatfield at an early stage is the best way to avoid surprises during the planning process. Daylight, sunlight and overshadowing are standard considerations for the council when judging the effect of development on neighbours and the quality of the homes being created. This guide explains how the local planning authority approaches the issue and what evidence you may be asked to provide.
Welwyn Hatfield Borough Council is the local planning authority (LPA) for the borough. Although Hertfordshire County Council is the upper-tier authority, it is the borough council that decides planning applications and sets the relevant development plan policies, so its documents are the ones that govern daylight assessment.
Daylight requirements in Welwyn Hatfield: the adopted Local Plan
The development plan is the Welwyn Hatfield Local Plan 2016-2036, which was adopted by the Council on 12 October 2023 and now carries full weight in decision-making, replacing the long-standing Welwyn Hatfield District Plan (2005). The plan is notable for the strong emphasis it places on design quality and on the living conditions of both existing and future residents.
Two policies are central to daylight and sunlight:
- Policy SP9 (Place Making and High Quality Design) is the strategic design policy. It requires proposals to deliver high quality design that responds to character and context, including the height, scale and design of buildings and the relationship to surroundings, all of which influence daylight and overshadowing outcomes.
- Policy SADM11 (Amenity and Layout) is the detailed amenity policy. It requires all proposals to create and protect a good standard of amenity and, in particular, to ensure that “the levels of sunlight and daylight within buildings and open spaces, and garden areas in particular, are satisfactoryâ€. SADM11 also seeks dual-aspect dwellings wherever feasible, a satisfactory outlook, development that is “not overbearing upon existing buildings and open spacesâ€, and naturally lit shared circulation space in flatted schemes.
These are supported by Policy SADM12 and the council's design guidance, so daylight and sunlight sit within a clear, joined-up policy framework.
Local daylight and sunlight guidance in Welwyn Hatfield
Welwyn Hatfield sets out its expectations through its validation requirements. The council's validation checklist confirms that a Daylight and Sunlight Assessment is required for major applications where there is a potential adverse impact upon the current levels of sunlight or daylight enjoyed by adjoining properties or buildings, including associated gardens or amenity space. It states that a daylight, vertical sky component, sunlight availability and shadow study should be undertaken and assessed against the criteria in the relevant BRE document, and that the information must be sufficient to determine existing and expected daylight, sunlight and overshadowing levels on neighbouring properties along with any mitigation. The checklist ties this requirement to Policies SP9, SADM11 and SADM12 and to Section 9 of the National Planning Policy Framework.
The applicable technical benchmark is the national standard: BRE BR 209 (2022), Site Layout Planning for Daylight and Sunlight: A Guide to Good Practice — the current edition of the BRE guide referenced in the council's validation requirements — read together with BS EN 17037 on daylight in buildings. These are applied through the Local Plan and the National Planning Policy Framework (NPPF), which expects a high standard of amenity for existing and future occupants.
A BRE-based assessment usually considers:
- Vertical Sky Component (VSC) and daylight distribution for affected windows;
- Annual Probable Sunlight Hours (APSH) for habitable rooms with a significant southerly aspect;
- Overshadowing of gardens and amenity space, typically tested for sunlight on the ground on 21 March.
What makes Welwyn Hatfield distinctive
Welwyn Hatfield is home to Welwyn Garden City, one of the original garden cities, whose spacious, tree-lined layout and generous spacing between buildings are part of its defining character. The Local Plan gives this special recognition through Policy SP15 (The Historic Environment of Welwyn Garden City), and much of the town centre and surrounding neighbourhoods lie within conservation areas. This garden-city grain, with its emphasis on openness, verges and landscaping, means that the scale, massing and spacing of new development, and therefore its daylight and overshadowing impacts, are scrutinised especially closely.
The borough's other main town, Hatfield, has a different character, with significant regeneration and higher-density opportunities, including around the town centre and the University of Hertfordshire. In these locations, where development is encouraged at higher densities in accessible places, robust daylight and sunlight evidence is often what determines whether a scheme is acceptable. Across both towns, common situations such as backland infill, rear and roof extensions, and flatted redevelopment regularly raise neighbour daylight and overshadowing questions.
How Fortress Associates can help
Fortress Associates prepares clear, robust daylight and sunlight assessments to BRE BR 209 (2022), BS EN 17037 and the NPPF, interpreted through the Welwyn Hatfield Local Plan. From a single extension in Welwyn Garden City to a larger development in Hatfield, our daylight and sunlight report service can test your proposal against the relevant benchmarks, identify neighbour impacts early, and support your planning submission. We work UK-wide, with a typical turnaround of four to five working days and no advance payment required. See our services page for more detail, or contact us to discuss your project. You might also like our companion guides on daylight requirements in Watford and daylight requirements in Hertsmere.
Sources & further reading
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