Rights of light against planning daylight assessment
A favourable daylight and sunlight assessment gives a developer less protection than it appears to. Rights of light are private easements enforced in the civil courts, and they run in parallel.
A planning permission does not authorise an interference with a right of light. That single fact is the reason schemes with permission get injuncted, and the reason a favourable daylight and sunlight assessment gives a developer less comfort than it appears to.
Rights of light are private property rights, enforced by adjoining owners in the civil courts. Planning daylight and sunlight is a public interest matter, judged by the local planning authority against guidance. Different legal basis, different measurement method, different thresholds, different decision maker, different remedy. The two run in parallel and neither disposes of the other.
The two regimes side by side
| Aspect | Rights of light | Planning daylight and sunlight |
|---|---|---|
| Legal basis | Private easement, usually acquired by 20 years of uninterrupted enjoyment | Development plan policy and national guidance |
| Who decides | The civil courts | The local planning authority, and the Planning Inspectorate on appeal |
| Method | Traditionally the Waldram approach, measuring sky factor at a working plane | Vertical sky component, no-sky line, annual probable sunlight hours, garden sunlight |
| Threshold | Whether adequate light remains for the ordinary use of the room | Reference values in the BRE guidance, applied flexibly |
| Remedy | Injunction, including mandatory injunction, or damages | Refusal, conditions, or approval |
| Timing | Can be raised before, during or after construction | Determined within the application period |
The threshold difference matters most. A room can lose a great deal of light and still retain enough for ordinary use, so a scheme can breach the BRE reference values comfortably while causing no injury a court would act on. The reverse also happens: a scheme that satisfies the council can still injure a neighbour's easement.
How a right of light arises
The common route is long use. Where light has passed over a defined aperture to a building for 20 years without interruption, a right can be acquired by prescription. Rights can also be granted expressly in a deed, or arise by implication on a sale of part.
Three practical points follow.
The right attaches to the aperture and the building, not to the land or to open space. A garden has no right of light. A window in a wall does.
The right is to a quantity of light for the ordinary use of the room, judged by reference to what the room is used for. A warehouse and a drawing office are not treated identically.
And the right can be prevented from arising. A light obstruction notice, registered as a local land charge, creates a notional obstruction that interrupts the 20 year period without anyone building anything. On a long-term development site with a neighbour approaching 20 years of enjoyment, that is a tool worth knowing about.
The remedy risk
The remedy is what makes rights of light a commercial issue rather than a technical one.
The courts can grant an injunction requiring a completed building to be cut back, and have done so. The 2010 High Court decision in the Heaney case, where a mandatory injunction was granted against a building already constructed, changed how lenders and insurers approach the subject. The Supreme Court's 2014 decision in Coventry v Lawrence, dealing with nuisance more broadly, revisited the approach to when damages should be awarded instead of an injunction, and the position is now more finely balanced than the older presumption in favour of an injunction.
That balance is not comfort. The point of an injunction risk is that it cannot be priced with confidence, and a neighbour who knows it exists negotiates accordingly.
Where a local authority is involved in land assembly, section 203 of the Housing and Planning Act 2016 allows interference with easements including rights of light where land has been appropriated or acquired for planning purposes, with compensation payable. That route is available on some regeneration schemes and not on ordinary private development.
What to do, and when
The sequence matters more than the technique.
- At acquisition, identify adjoining buildings with windows facing the site and establish their age. Anything over 20 years old with unaltered apertures is a candidate.
- Commission a rights of light appraisal at the same time as the planning daylight work, from the same model, so the two use identical geometry.
- Identify which neighbours have losses capable of supporting a claim and rank them by severity.
- Consider insurance early. Rights of light policies exist, and the terms depend on what is disclosed and on whether a neighbour has already been approached.
- Decide on a negotiation strategy before anyone contacts a neighbour, because an approach that reveals the developer's concern changes the negotiation.
- Where releases are needed, allow for a deed of release and the time it takes to complete.
Point four and point five interact awkwardly, and this is where developers make expensive mistakes. Approaching a neighbour before an insurance policy is in place can affect availability of cover. Getting the order wrong is a real cost.
The planning side of the same building
The planning assessment runs on its own timetable and its own metrics. A Daylight and Sunlight Assessment prepared to the BRE guidance covers vertical sky component and the no-sky line for existing neighbouring rooms, annual probable sunlight hours for windows facing within 90 degrees of due south, and the internal daylight performance of the proposed units.
Where gardens and amenity space are affected, an Overshadowing Study deals with sunlit area on 21 March. Gardens have no rights of light, so this is purely a planning matter.
The BRE guidance is explicit that its numerical values are guidance to be applied flexibly, particularly in dense urban areas where meeting the suburban reference values is not realistic. That flexibility is a planning argument, made in the Planning Statement alongside the other material considerations. It carries no weight at all in a civil claim.
Method, and an honest disagreement
The traditional rights of light method assesses the proportion of a room receiving a defined sky factor at a working plane, with the conventional threshold set at half the room area. It is a nineteenth century construct, it takes no account of glazing transmittance, room reflectance or the direction of the sky, and practitioners have argued about it for decades.
Radiance-based and climate-based methods give a more realistic picture of how light actually reaches a room. They are also less predictable in litigation, because the courts have decades of familiarity with the older approach.
The Law Commission examined rights of light and reported in 2014 with recommendations for reform, including a statutory notice procedure. Those recommendations have not been implemented. Anyone advising on this should treat the law as it stands rather than as it might become.
Illustrative example. A four storey infill scheme passes the planning daylight tests for all but two neighbouring windows, and the council grants permission. A rights of light appraisal shows one first floor room in the adjoining building, in use as a bedroom for over 30 years, losing enough light to support a claim. The scheme is amended to set back the upper floor on that boundary, which costs one unit and removes the injunction risk. This example is illustrative only.
The practical summary for an investor
Treat the planning result and the rights of light position as two separate items on the risk register. Budget for both surveys. Assume that a permission does not protect you, and that a neighbour with an easement has bargaining power independent of the planning process.
And do the rights of light work before the funding is drawn rather than after the frame is up.
This is general guidance, not legal advice. Rights of light is a specialist area of property law, and a chartered surveyor experienced in the field and a solicitor should be instructed before any decision is taken.
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Frequently asked questions
Does planning permission override a right of light?
No. A right of light is a private easement enforced in the civil courts, and planning permission gives no defence to a claim. The only routes that override easements are express statutory powers, such as section 203 of the Housing and Planning Act 2016 where a local authority has appropriated or acquired the land for planning purposes.
How does a right of light arise?
Most commonly by prescription, where light has passed over a defined aperture to a building for 20 years without interruption. Rights can also be granted expressly by deed or arise by implication on a sale of part. The right attaches to the aperture and the building, so gardens and open land have no right of light.
Can a completed building be ordered to be cut back?
Yes. The courts can grant a mandatory injunction, and did so in the Heaney case in 2010, which changed how lenders and insurers view the risk. The Supreme Court's 2014 decision in Coventry v Lawrence revisited when damages should be awarded instead, so the position is more finely balanced than a presumption either way.
Is the measurement method the same as for planning daylight?
No. Rights of light traditionally use the Waldram approach, assessing the proportion of a room receiving a defined sky factor at a working plane. Planning uses vertical sky component, the no-sky line and annual probable sunlight hours from the BRE guidance. The thresholds and the questions they answer are different.
When should a rights of light appraisal be commissioned?
At acquisition or early design stage, from the same three dimensional model as the planning daylight work so the geometry is identical. Decide on the insurance and negotiation strategy before approaching any neighbour, because an approach can affect the availability of cover and changes the negotiation.
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.