News & Insights

Rights of Light

A right of light is a legal right (a type of easement) which benefits one property (“A”) and burdens its neighbouring property (“B”) by preventing the construction on “B” of a building which would reduce, to a material degree, the light enjoyed by “A”’s windows.

Whilst a right of light may be expressly granted by deed or transfer, or arise by way of an implied grant, it is more frequently acquired by prescription once it has been continuously enjoyed (i.e. not interrupted) for a period of 20 years.

Rights of light are enjoyed by freeholders and, depending on the precise terms of a lease, may also be claimed by leaseholders.

Calculating the extent of an infringement

What constitutes an actionable interference with a right of light is a matter of detailed scientific analysis.  A sufficient amount of light to enable “visual discrimination” (generally, clerical-type tasks) is the light given out by a 1-foot candle over 1 square foot (a “lumen”).  An average overcast sky provides 500 lumens per square foot, and so 0.2% of the sky factor affords adequate light.  The 0.2% sky factor is measured at the “working plane”, which is 850mm above floor level.  A rights of light consultant plots on a floor plan a contour where 0.2% of the sky factor currently exists at the working plane within a room, and a new contour were the proposed building to be constructed (and so less sky observed).  This produces the area over which light is reduced to 1 lumen.  The area of the loss of light is then zoned according to the importance of the light to the room in question.  The room is divided into four equal zones, and the area of loss is multiplied by factors ranging from 0.25 to 1.5, the sum of which gives rise to what is known as the effective first zone (or “EFZ”).  Though not a hard-and-fast rule, the courts normally take the view that if 0.2% sky visibility is available over half the area of a room then there is sufficient light (the “50/50 rule”).

The availability of artificial light within a property does not mean that a reduction in the light entering windows is not an actionable nuisance, although it may affect the owner of “A”’s ability to obtain an injunction – an injunction is a primary entitlement, but a court has a discretion to award damages instead.

Assessing damages

Where a court awards damages in lieu of an injunction it will assess what might reasonably have been demanded as a “release fee” in a hypothetical negotiation (also known as Wrotham Park damages).  The developer of “B” will favour a calculation of release fee damages on the basis of book value.  Book value is arrived at my multiplying together the “light rent” (a hypothetical proportion of the rental value attributable to light; usually £5 per square foot), the EFZ area (the area of light lost), and the year’s purchase for the building (the inverse of its yield x 100).  Once calculated, the book value is then subject to an uplift to take account of “A”’s bargaining position (often 3 to 5 times the book value).  “A” will argue against an assessment of damages on the basis of book value and an uplift, and will contend that they should be a percentage of the profit that “B” will make on its development.  A specialist rights of light surveyor will create a CAD model showing a “cutback” – a reduction in the proposed scheme so that what remains would not cause an actionable nuisance to “A”’s building.  Development appraisals are produced for each of the two schemes, and a court then considers what a fair proportion of the additional profit (for the “unrestrained” scheme) would be.  An alternative, and simpler, assessment is to calculate the average profit per square foot for the proposed development, and apply this to the area of lost development identified in the cutback.

How can an intending developer defeat a right of light?

The owner of “A” can be prevented from acquiring a prescriptive right of light by interrupting their enjoyment of the light for a period of 1 year.  Erecting a sufficiently large hoarding (what used to be known as a “spite screen”) might be impractical and/or in breach of planning control, and so statute has intervened.  Under the Rights of Light Act 1959 “B” may apply for the registration of a light obstruction notice (a “LON”) against “A”’s property.  That notice (registered as a local land charge) operates as a notional obstruction of the light crossing “B”’s property to the windows in “A”’s property.  “A” has 1 year in which to object to a LON by demonstrating that a right of light (by prescription or otherwise) already exists.  However, if “A” fails to object in time their right of light is deemed to have been interrupted, and the presumption clock is reset to zero.  LONs are useful tools for developers, as they will flush out or defeat neighbours who assert entitlement to rights of light.

The insurance alternative

Insurance can safeguard a developer’s risk should rights of light be asserted.  Cover should be explored before a right of light is claimed and the proposed development is objected to, as otherwise it is unlikely to be available and “B” will be left to negotiate with “A”.  There are various insurance products available in the market, some of which may prohibit the developer from engaging with their neighbours (and merely dealing with a claim only once it is made), and others which  may permit the developer to adopt a more proactive approach by engaging with the owners of neighbouring risk properties.

Statutory powers

In some circumstances Section 203 of the Housing and Planning Act 2016 permits a developer to override rights of light, with the resulting interference being compensated on the same basis as a  compulsory purchase.  The measure of compensation is normally the diminution in value of the affected property.  The land on which development is proposed must have been vested in or acquired by a specified or qualifying local authority.  It is open to a local authority to acquire land for planning purposes and then to dispose of that land to an intending developer.  So, if the assertion of rights of light is likely to frustrate a development of which a local authority is in favour, then that local authority might be persuaded to acquire the land from the developer and then sell it back, the purpose of Section 203 being to facilitate developments which are in the public interest.  However, the criteria to be applied by a local authority are many and complex, and it would need to be convinced that there was a compelling case in the public interest for the powers conferred by Section 203 to be exercised.  If “B” seeks to avail itself of the benefits of Section 203 it will need to show that reasonable efforts have been made to try and agree a settlement with “A”.

If you require particular advice on any rights of light issues, then please contact our Property Litigation team.