Right to light against planning daylight: two tests

Right to light versus planning daylight is a comparison between a private property right and a planning judgement, and the two have almost nothing in common beyond the word light. A right to light is an easement enforceable in the courts, measured by a method developed in the early twentieth century, with an injunction as a possible remedy. Planning daylight is a material consideration assessed by the local planning authority against BRE guidance. A scheme can pass the planning assessment comfortably and still be stopped by a neighbour with an easement.

The civil easement and how it is acquired

A right to light is a negative easement benefiting a defined aperture in a building, not the building generally and not the land. It arises in three ways: express grant in a deed, implied grant on a sale of part, or prescription under the Prescription Act 1832 after 20 years of uninterrupted enjoyment.

Prescription is the common route and the one that catches developers. Twenty years of light through a window, without consent and without interruption, and the easement exists whether anyone has thought about it or not. A neighbouring owner can interrupt the period by registering a light obstruction notice under the Rights of Light Act 1959, which operates as a notional screen and stops the clock, and that is worth knowing if you own land next to a building approaching the twenty-year mark.

The right is to sufficient light for the ordinary use of the room, not to all the light currently enjoyed. That principle comes from Colls v Home and Colonial Stores [1904] and it means a reduction, even a substantial one, only gives rise to a claim if what remains falls below the standard of adequacy.

The planning assessment and who applies it

Planning daylight and sunlight is assessed by the local planning authority as part of the amenity judgement under section 70 of the Town and Country Planning Act 1990, usually against BRE 209 (2022) and whatever the local plan says about it.

The familiar tests are the vertical sky component, with a reference value of 27 per cent and a comparison against 0.8 of the former value, the no-sky line for daylight distribution, and annual probable sunlight hours for sunlight, with a comparison against 0.8 of the former value for both the annual and winter figures. BRE presents these as guidelines to be applied flexibly, and local plan policies vary in how tightly they hold the figures, which we look at in the note on local plan amenity policies and how they use BRE 209.

The decision maker weighs the result against everything else. A scheme causing losses beyond the guidelines can be approved where the planning benefits justify it. No court is involved and no property right is adjudicated.

Why a planning permission is no defence

Planning permission authorises development in public law. It does not transfer, extinguish or modify a private easement, so the holder of a right to light can sue whatever the council has approved.

The remedy is the part that focuses minds. The court has a discretion to award damages in lieu of an injunction, and the principles governing that discretion were restated by the Supreme Court in Coventry v Lawrence [2014] UKSC 13. But a mandatory injunction requiring part of a completed building to be cut back has been granted, as in HKRUK II (CHC) Ltd v Heaney [2010], and the possibility of that outcome is what drives settlement negotiations.

There is one statutory override worth knowing. Where land has been acquired or appropriated by a qualifying authority for planning purposes, section 203 of the Housing and Planning Act 2016 allows development to proceed notwithstanding interference with an easement, converting the neighbour's claim into one for compensation. It is not available to a private developer acting alone, and it depends on the authority's involvement and on the statutory conditions being met.

The measurement conventions each uses

Rights of light analysis works from sky factor at a working plane 850 millimetres above floor level, expressed as a percentage of the total sky dome. The conventional adequacy threshold is 0.2 per cent sky factor, and a room is treated as adequately lit where at least half its area receives that. The contour separating adequately lit from inadequately lit area is called the grumble line, and the analysis compares the before and after positions room by room.

The planning tests measure something different. Vertical sky component is taken at the centre of the window on its outside face, so it says nothing about the room behind. The no-sky line is plotted inside the room but against a different criterion. Annual probable sunlight hours is about sun rather than skylight altogether.

Two consequences follow. The numbers are not interchangeable, and a report that presents both without explaining which convention produced which figure is confusing rather than thorough. And the geometry that matters differs: rights of light is sensitive to room depth and window size, while vertical sky component is driven entirely by the obstruction angle outside.

When to commission each study

The sequencing is the practical heart of this. A rights of light appraisal belongs at acquisition or early design stage, before the massing is fixed, because the cost of a release or an insurance premium is a land cost and the design can still be adjusted at little expense.

The planning study belongs with the application, once the scheme is settled enough to model. By then the rights of light position should already be known.

Illustrative example: a five-storey infill scheme next to a Victorian terrace converted to offices. The planning study shows vertical sky component losses within the 0.8 guideline for all but two windows, and the authority accepts the scheme. A rights of light appraisal, commissioned late, shows two second-floor rooms dropping below the adequacy convention. The developer negotiates a release with a payment and a deed of easement, having lost the opportunity to set back the upper storey at no cost. The scenario is illustrative rather than drawn from a real case.

Insurance, releases and what a planning statement should say

Three routes deal with an identified infringement. A negotiated release by deed, priced on the loss and often on a share of developer profit. Rights of light indemnity insurance, which covers the financial consequence rather than removing the risk, and which insurers will usually only write where no neighbour has been approached. And design change, which costs nothing early and a great deal late.

The order matters. Approaching a neighbour can make insurance unavailable, so take advice on the sequence before any contact is made.

For the planning submission, keep the two subjects apart. A planning statement or a Daylight and Sunlight Assessment should deal with the BRE tests and the local plan policy, and should not assert that the scheme complies with rights of light, because that is a private law question the authority has no jurisdiction over. Equally, an objector's claim to hold an easement is not a reason for the council to refuse. Where the issue is construction-stage rather than permanent, that is a separate analysis again, set out in our piece on temporary loss of daylight during construction, and overshadowing of gardens and amenity space is dealt with by an Overshadowing Study rather than by either of these tests.

Enter your postcode on PlanScope to draft the amenity sections of a supporting statement and see which assessments your scheme is likely to need.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. Rights of light is a private law matter requiring specialist legal and surveying advice.