Daylight requirements in Mid Sussex are a key consideration for anyone proposing a new home, an extension or a larger residential scheme across this central West Sussex district. Mid Sussex covers the three main towns of Haywards Heath, Burgess Hill and East Grinstead, together with a network of villages set within attractive countryside, much of it falling within the High Weald National Landscape (formerly the High Weald Area of Outstanding Natural Beauty). With sustained housing growth and sensitive landscape and townscape settings, the protection of daylight and sunlight to existing and future homes is something the council takes seriously. This article explains how the local framework works.
The local planning framework in Mid Sussex
The local planning authority (LPA) is Mid Sussex District Council; West Sussex County Council is not the LPA for these decisions. The current development plan comprises the Mid Sussex District Plan 2014-2031, adopted on 28 March 2018, together with the Site Allocations Development Plan Document, adopted on 29 June 2022, which allocated additional housing and employment sites across the district.
For daylight and sunlight, the most directly relevant policy in the District Plan is:
- Policy DP26 (Character and Design), which requires development to be of high quality and to respond to its context, and which seeks to ensure that proposals do not cause significant harm to the amenities of existing nearby residents and adjoining occupiers, nor to the amenities of future occupants of new dwellings.
Policy DP26 works alongside the District Plan's wider design and housing policies, including its expectations for well-designed, healthy living environments. Daylight and sunlight are central to that amenity test: a scheme that materially reduces the light reaching a neighbour's windows or garden, or that fails to provide adequate daylight within new homes, risks conflict with DP26.
The Mid Sussex Design Guide SPD
Mid Sussex is better served than many districts by clear supplementary guidance. The council adopted the Mid Sussex Design Guide Supplementary Planning Document on 4 November 2020. The Design Guide expands on Policy DP26 and includes a dedicated Residential Amenity section that deals explicitly with daylight and sunlight, drawing on the established Building Research Establishment methodology — including the familiar angular rules of thumb such as the 25-degree obstruction angle used as an initial check on the daylight available to a window.
Because the Design Guide signposts the BRE approach rather than inventing its own numerical thresholds, daylight and sunlight assessments in Mid Sussex are prepared against the recognised national and international benchmarks:
- BRE BR 209 (2022) — the current Building Research Establishment guide Site Layout Planning for Daylight and Sunlight, providing the vertical sky component (VSC), no-sky-line (daylight distribution), annual probable sunlight hours (APSH) and overshadowing tests.
- BS EN 17037 — the standard Daylight in Buildings, used to show that new dwellings achieve adequate internal daylight.
- The National Planning Policy Framework (NPPF), which requires a high standard of amenity for existing and future users while supporting efficient use of land.
The council's validation requirements determine the supporting information needed to register an application, scaled to the size and sensitivity of the proposal. For schemes where massing or height could materially affect neighbouring light, a BRE BR 209 daylight and sunlight assessment is the natural way to demonstrate compliance with DP26 and the Design Guide.
What daylight requirements in Mid Sussex mean in practice
Several local characteristics shape how these assessments are read:
- Three growing towns. Haywards Heath, Burgess Hill and East Grinstead are all seeing infill, redevelopment and town-centre intensification, where taller buildings and tighter plots make daylight and sunlight impacts more likely to arise.
- Major strategic growth. Large allocations such as the development around Burgess Hill bring higher-density layouts where daylight within new homes, and overshadowing between blocks, need to be carefully designed and evidenced.
- High Weald National Landscape. Much of the district lies within or close to the High Weald, where the quality of design and the relationship of buildings to one another and to their setting attract particular scrutiny.
A well-prepared assessment measures the existing daylight and sunlight to neighbouring windows and amenity areas, models the proposed development, and compares the results with the BRE BR 209 guidelines. Where the proposal meets those targets it provides robust evidence of compliance with Policy DP26 and the Mid Sussex Design Guide. Where a target is not fully met, the report can explain the local context, the scale of any change and any mitigation, supporting a balanced and evidence-led decision rather than a precautionary refusal.
Common triggers for an assessment in Mid Sussex
- Two-storey or first-floor extensions close to a shared boundary.
- Infill and back-land dwellings within an established residential area.
- Apartment and mixed-use schemes in the three town centres.
- Higher-density development on strategic allocation sites.
How Fortress Associates can help
Fortress Associates provides our daylight and sunlight report service to BRE BR 209 (2022) and BS EN 17037, set within the policy framework of the Mid Sussex District Plan and the Mid Sussex Design Guide SPD. We work nationwide, typically turn reports around within four to five working days, and ask for no advance payment. See our services page or use our contact page to get started. For schemes in neighbouring areas, our guide to daylight requirements in Crawley may also be useful.
Sources & further reading
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