What is a right of light survey?
A right of light survey is a technical analysis of the daylight and sunlight impact of a proposed development on neighbouring properties. It is used by developers, architects, and planning consultants to demonstrate that a new building does not unreasonably reduce the daylight to existing windows, and to identify any compensation or design changes that may be needed.
There are two related but legally distinct frameworks in 2026:
- The Rights of Light Act 1959 — a legal nuisance framework that gives adjoining owners a prescriptive easement to light through defined windows after 20 years of uninterrupted enjoyment. A reduction below the "sufficient light according to the ordinary notions of mankind" threshold can be an actionable nuisance. A right of light survey in this sense is a legal analysis prepared for negotiation, mediation, or court.
- BRE 209 ("Site layout planning for daylight and sunlight") — a planning guidance framework used by local planning authorities when assessing planning applications. The 2022 3rd edition of BRE 209 sets out the methodology for Vertical Sky Component (VSC), No-Sky Line (NSL), and average daylight factor (ADF) calculations.
A 2026 right of light survey typically addresses both frameworks — the legal nuisance analysis for the affected neighbours and the BRE 209 analysis for the planning application. The two use similar inputs (a 3D model of the site, the proposal, and the surrounding buildings) but different tests.
2026 cost bands
A 2026 right of light survey in the UK typically lands in the following bands (ex VAT):
| Project | Typical 2026 cost | Notes |
|---|---|---|
| Rapid feasibility / screening (small scheme) | £750–£1,800 | Indicative VSC test, 2–3 neighbours |
| Full right of light survey (small urban infill) | £1,800–£3,500+ | BRE 209 analysis, 3D model, written report |
| Typical multi-façade urban development | £3,500–£6,000+ | Multiple neighbours, multiple design options |
| Large multi-façade development with negotiation | £6,000–£10,000+ | Multiple iterations, expert input, neighbour negotiation |
A right of light survey is highly bespoke and the fee is driven by the number of affected windows, the number of neighbours, the quality of the input model, and the number of design options to be tested.
What's included in a 2026 right of light survey
A standard right of light survey includes:
- 3D model of the site, the proposal, and the surrounding buildings — usually derived from a measured building survey, an architect's BIM model, or both.
- Identification of windows enjoying potential rights — the windows of neighbouring properties that have had uninterrupted light for 20+ years and that may be affected by the proposal.
- Vertical Sky Component (VSC) calculation at each affected window, before and after the proposal, using Waldram diagrams.
- No-Sky Line (NSL) calculation for each affected room, before and after the proposal.
- Average Daylight Factor (ADF) calculation where the design requires it (typically for residential schemes under the planning daylight test).
- Comparison against the BRE 209 target values — VSC ≥ 27% (or a 20% relative reduction), NSL ≥ 0.8 of the room area, ADF ≥ 2% for kitchens, ≥ 1.5% for living rooms.
- Written report with the methodology, the inputs, the calculations, the results, and any recommendations for design changes or compensation.
- 3D visualisations (optional) — sky view renderings and daylight heat maps.
When to commission a right of light survey
A right of light survey is the right answer in four situations:
- Planning application for an urban infill or extension — most LPAs require a BRE 209 daylight and sunlight assessment for any development that may affect neighbours.
- Acquiring a development site — a right of light survey identifies the daylight constraints on the site before acquisition, allowing the developer to factor them into the offer price.
- Designing a scheme to minimise neighbour impact — the architect uses the VSC and NSL outputs to design massing, set-backs, and roof forms that minimise daylight loss to neighbours.
- Negotiating with a neighbour — if a neighbour has threatened a right of light injunction, a right of light survey quantifies the actual daylight loss and supports a negotiated settlement.
Methodology
A 2026 right of light survey typically uses a 3D model of the site and surrounding buildings (built in specialist software such as Autodesk Revit, SketchUp, or AutoCAD) and applies the BRE 209 tests in software such as IES VE, Sefaira, orco.tech's "Rights of Light" module, or Ecosurv's SkyCalc. The outputs are the VSC, NSL, and ADF values for each affected window, before and after the proposal, and a written report summarising the results.
A measured building survey of the affected neighbour's property is often the right starting point for a right of light analysis, because the 3D model of the surrounding buildings has to be accurate to ±20–50 mm for the VSC and NSL calculations to be defensible.
Turnaround time
A 2026 right of light survey typically delivers in 3–6 weeks, depending on the number of affected windows, the number of design options to be tested, and the speed of the input data. A rapid feasibility screening can be delivered in 1–2 weeks.
How to commission a right of light survey
- Send the project address and a brief. Outline the proposed development (extension, new build, change of use), the number of affected neighbours, the LPA's planning requirements, and the deliverable requirement (BRE 209 report, legal nuisance analysis, or both).
- Receive a bespoke fixed-fee quote based on the project scope. Most 2026 quotes are returned within 24–48 hours.
- Input data collection. The architect's BIM model, the LPA's planning portal CAD files, and (often) a measured building survey of the affected neighbours' properties.
- 3D model construction and VSC/NSL/ADF analysis. 1–3 weeks depending on the project scope.
- Report production. 1–2 weeks.
- Issue deliverables. Written report, 3D visualisations, raw VSC/NSL/ADF outputs.
A right of light survey is the right answer for any urban development that may affect neighbours' daylight. Without a defensible VSC and NSL analysis, the planning application is at risk of refusal on amenity grounds, and the neighbour has a credible right of light injunction claim. The cost of a £2,000 survey is dwarfed by the cost of a planning refusal or an injunction.
Frequently asked questions
Is right of light a planning test or a legal test? Both, but different tests. The planning test (BRE 209) is used by the local planning authority to assess the daylight impact of a new development on neighbours. The legal test (Rights of Light Act 1959) is a common-law nuisance that gives adjoining owners a prescriptive easement to light after 20 years. A right of light survey typically addresses both, with the BRE 209 analysis for the planning application and the legal analysis for any compensation or negotiation.
What is the difference between VSC and NSL? VSC (Vertical Sky Component) is a measure of the amount of skylight reaching the centre of a window, calculated using a Waldram diagram. NSL (No-Sky Line) is a measure of the area of a room that can see the sky from a working plane. VSC is the primary test for daylight impact; NSL is a secondary test that gives a more visual sense of the impact on the room.
What is the BRE 209 target for VSC? The BRE 209 target for VSC is 27% as a target value, with a 20% relative reduction as a "noticeable" impact. If the proposed development reduces the VSC below 27% or by more than 20% of the existing value, the impact is considered significant and may need to be mitigated (design change, compensation, or both). The actual LPA test depends on the local plan and the planning officer.
What is the typical compensation payment? A 2026 compensation payment for a right of light infringement depends on the loss in value of the affected property. A typical urban infill with a 20% VSC reduction might attract £20,000–£100,000 in compensation per affected neighbour, depending on the property value, the number of affected windows, and the level of the impact. Compensation is negotiable and is usually paid as a lump sum.
Can a right of light issue stop a planning application? Not directly — a right of light issue is a private legal matter, not a planning matter. But the planning application can be refused on daylight and sunlight amenity grounds (under BRE 209), and the LPA will typically require the developer to demonstrate that the daylight impact on neighbours is acceptable before approving. A right of light survey supports both the planning application and the private negotiation with neighbours.