Rights of light or a daylight and sunlight assessment
A right to light is a private property right measured by sky factor and enforceable by injunction. Planning amenity is a material consideration measured by BRE guidance. Both run on the same scheme.
A right to light is a private property right that can be enforced in court. A daylight and sunlight assessment is planning evidence that informs a public law decision. The rights of light vs daylight assessment distinction matters because a scheme can pass every planning test and still be stopped by a neighbour with an easement, and planning permission is no defence to that claim.
Developers who learn this late learn it expensively. The two workstreams start at the same time on any scheme that builds close to existing windows.
The confusion is understandable, because both exercises produce tables of numbers about light reaching a window, and both are carried out by surveyors. The tables mean different things and answer to different tribunals.
A property right against a planning consideration
An easement of light attaches to a particular window in a particular building. It is owned by whoever owns that building, it runs with the land, and it is enforced through the civil courts.
Planning amenity is different in every respect. The local planning authority weighs the effect of a proposal on the living conditions of neighbours as one material consideration among many, and it can grant permission despite a loss of light where the benefits justify it. The decision binds the authority and the applicant. It does not bind the neighbour, whose private rights survive untouched.
The clearest way to hold the distinction is that planning asks whether the effect is acceptable in the public interest, and the law of light asks whether an owner's legal entitlement has been infringed.
How a right to light is acquired and measured
Most rights arise by prescription. Section 3 of the Prescription Act 1832 provides for the acquisition of a right to light by 20 years of uninterrupted enjoyment through a defined aperture. Rights can also arise by express grant, by implied grant on a sale, or under the doctrine of lost modern grant.
The measurement is unfamiliar to anyone coming from the planning side. The test set by the courts is whether enough light remains for the ordinary use of the room according to the ordinary notions of mankind, and surveyors apply it using sky factor calculations at working plane height, identifying the area of the room that retains adequate light. A common convention treats a room as adequately lit where at least half its area remains above the threshold, with the injury measured by how much of that area is lost.
Two points follow. The analysis is room by room and window by window rather than facade by facade. And a room already poorly lit can be more vulnerable than a well lit one, because a small absolute loss can take a large share of what remains.
Interruption is a defence. The Rights of Light Act 1959 allows a notional obstruction to be registered as a local land charge, which stops the 20 year period running. Owners of development land use that mechanism to prevent rights maturing over a site they intend to build on.
The planning tests and where they come from
Planning uses the BRE site layout guidance. The familiar measures are vertical sky component at the centre of each window, the no sky line test for daylight distribution within a room, and annual probable sunlight hours for sunlight, together with the guidance on sunlight to amenity areas.
Those numbers are guidance, and the guidance says so. Local plans in dense urban areas often adopt alternative daylight targets, and inspectors accept departures where the context justifies them. A Daylight and Sunlight Assessment that treats the figures as thresholds to be passed rather than as a starting point for judgement misreads the document it relies on.
If you want the detail of the single most quoted figure, what 27 per cent actually measures is worth reading before the first design review.
Different professionals, different reports
The two pieces of work are usually done by different people. Rights of light is the province of specialist surveyors who understand the legal test, the conveyancing history and the negotiation, and their report is typically produced under legal privilege because it quantifies exposure.
The planning assessment is produced by a daylight consultant for submission and publication. It goes on the council's website, where the neighbours read it.
That difference in audience is the reason not to merge them. A public document that sets out the scale of a private law injury hands a negotiating position away, and the calculations are not interchangeable in any event, since one measures sky factor at working plane and the other measures sky visibility at the window.
Remedies on each side
Planning remedies are limited to the decision. Permission is refused, or granted with conditions, or granted with a design amendment negotiated during the application.
Civil remedies are sharper. A court may award damages, and it may grant an injunction requiring a completed building to be cut back. Injunctions are discretionary and the courts have set out the considerations that guide the choice between an injunction and damages, but the possibility is real enough that lenders and insurers ask about it.
That is why the planning permission that ignores a right to light is a live risk rather than a theoretical one.
Insurance, releases and statutory override
Three mechanisms manage the exposure.
- A negotiated release, where the affected owner is paid to release or vary the right, usually documented by deed.
- Rights of light insurance, which covers the cost of a claim and is priced on the strength of the exposure and on whether the neighbour has been approached. Approaching a neighbour first can make cover unavailable, so take advice before making contact.
- The statutory override in the Housing and Planning Act 2016, which allows interference with easements where land has been appropriated or acquired by a qualifying authority for planning purposes, converting the right into a claim for compensation.
The third route involves the local authority and takes time, and authorities apply their own policies to requests. It is a tool for larger schemes rather than a routine answer.
Running both workstreams on one scheme
Sequence them like this:
- At feasibility, commission a desk based rights of light appraisal on the massing, and a coarse daylight test on the same model.
- At design development, refine both and use the results together, because a massing change that fixes one usually helps the other.
- Before submission, finalise the planning assessment for publication and keep the rights of light analysis separate.
- In parallel, take advice on insurance before any approach to neighbours.
- After permission, resolve the private rights before starting work rather than after.
The costs of getting the order wrong are not symmetrical. A planning objection delays a scheme. An injunction removes floors from it.
Work out the full document list for the application at the same time: enter your postcode on PlanScope to see which reports the site is likely to need.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.
Frequently asked questions
Does planning permission override a right to light?
No. Permission is a public law consent that binds the authority and the applicant. A right to light is a private easement owned by a neighbour, and it survives the grant of permission. A neighbour can seek damages or an injunction against a scheme that has full permission and satisfies every planning test.
How is a right to light acquired?
Most commonly by prescription under section 3 of the Prescription Act 1832, through 20 years of uninterrupted enjoyment of light through a defined aperture. Rights can also arise by express grant or by implied grant on a sale. A notional obstruction registered under the Rights of Light Act 1959 stops the period running.
Are the calculations the same as a planning daylight assessment?
No. Rights of light analysis measures sky factor at working plane height and identifies the area of a room retaining adequate light, usually applying a convention about half the room area. Planning uses vertical sky component at the window, the no sky line and annual probable sunlight hours from the BRE guidance.
Can a court order a completed building to be cut back?
It can. Injunctions are discretionary and courts weigh a number of considerations before choosing between an injunction and damages, but orders requiring parts of a building to be removed have been made. That possibility is why lenders and insurers ask about rights of light exposure on schemes built close to existing windows.
When should I approach a neighbour about their rights?
Take advice on insurance first. Cover for rights of light exposure is priced partly on whether the affected owner has been approached, and an early conversation can make insurance unavailable or much more expensive. Sequence the appraisal, the insurance advice and any negotiation deliberately rather than starting with a letter.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.