You are here: The Right To Light


The aim of this presentation is to give you a general understanding of daylighting/sunlighting and rights of light, provide you with the general terminology used and legislation that applies.
Both daylighting/sunlighting and rights of light fundamentally deal with natural lighting to buildings. They both achieve the same objectives in that they aim to maintain good daylighting and sunlighting levels within buildings.
However, there is a clear distinction between daylighting/sunlighting and rights of light in that daylighting/sunlighting is a planning issue whereas rights of light is common law. The planning authorities are normally only concerned with daylighting/sunlighting issues to residential properties, schools and sometimes student accommodation where the amenity for daylighting/sunlighting is essential. They are generally however not concerned with daylighting and sunlighting levels to commercial properties such as offices, as it is common practice to use artificial lighting throughout the day.
Rights of light on the other hand is completely different in that it identifies any window openings as potentially having a right to light and these issues can be raised whether a planning application has been granted or not. It is therefore essential to look at both these issues at the earliest stage possible so that the planning authorities do not raise any issue with regard to daylight/sunlighting and that you know what risks there might be with regard to rights of light.

Relevant documents for Daylight/Sunlight

With regard to daylighting and sunlighting there are two main documents that most planning authorities refer to. The primary document is the BRE Guidelines, which cover daylighting and sunlighting to new developments, to surrounding developments and to open spaces and amenity areas.
The other document, which is referred to within the BRE Guidelines, is the British Standards Lighting for Buildings Code of Practise for Daylighting.
The BRE Guidelines themselves were developed as guidelines and therefore are not statutory. However some local authorities have taken the BRE Guidelines and written them into their UDP in such a way that they almost become mandatory. Other local authorities however do not even ask for daylighting and sunlighting studies or state anything within their UDP. They might however raise objections with regard to bulk and massing which in our experience is the main factor within poor daylighting and sunlighting levels.
However, with the advent of the Human Rights Act it is becoming apparent that local authorities are having to ask for daylighting and sunlighting calculations to be performed to most developments as they have to protect their position and accountability.
As stated before, the British Standards are mentioned in the BRE Guidelines. In our experience the British Standards are normally used for assessing the internal daylighting levels to proposed residential rooms. These are not necessarily asked for, but we have found that with developments in tight inner city areas or where proposals have courtyards or internal spaces, internal daylighting calculations have been requested.


With regard to daylighting there are three terms that you might hear, these being the Vertical Sky Component which is abbreviated to VSC, the Average Daylight Factor which is referred to as ADF and No-Skyline Assessment (also known as the daylight distribution test).
The Vertical Sky Component is an externally assessed calculation and does not require room use or sizing. There are minimum standards set by the BRE guidelines, but if these are not met then you can compare between the existing and proposed situations, with an allowable reduction of up to 20% being permitted.
The Average Daylight Factor is an internally assessed calculation and requires room use and area of the floor, walls and ceiling. There are minimum standards set by the BRE guidelines which should be met.
The No-Skyline Assessment is an internally assessed calculation which requires room sizing and floor to sill height. This calculation compares the pools of light where direct daylight falls within a room at desk top height. There is no minimum recommendation, instead the existing and proposed situations are compared, with a 20% reduction being permitted.
The Vertical Sky Component calculation is generally used on surrounding residential properties as internal layout of surrounding residential properties are not always known and planners do not want to hear speculation about the possible layout. If information is known then you should apply all three test.


With regard to sunlighting, the terminology used here is the Annual Probable Sunlight Hours which is shortened to APSH. This measures the amount of actual sunlight penetration to a window and is of course dependent on the orientation to north. The sunlighting calculations only need to be calculated to faces that lie within 90o of due south. Any north facing elevations do not have an expectation of sunlight and therefore are not assessed.


Another sunlighting study that might be requested by a local authority is an overshadowing study. This is normally shown by a series of rendered images showing the shadow cast by the proposed development on an hour by hour basis at certain times of the year. We usually use June, March and December on the 21st of the month.
The overshadowing studies are generally a good visual aid for the man of the street to read so that they can actually see the sun shadow path moving around the site and how it might affect a property. However the overshadowing study does not have any quantifiable result in which to comment on so therefore it can only be used as a reference guide.

When the Subject Building Does Not Meet the BRE Criteria

The BRE Guidelines were designed to be used flexibly and therefore this allows some degree of argument for daylighting and sunlighting levels that do not achieve the minimum requirements. Some of the arguments that we use on a frequent basis are as follows.
That the Vertical Sky Component minimum value should not be strictly applied to inner city developments. Historically the daylighting levels are set from two terraced houses 12 m apart with ground and first floor levels with a pitched roof. This can not always be applied in a dense inner city area where a two storey development is really not possible.
Another argument that we might use is where a site is undeveloped and has been so for a long time. We argue that is it is an unfair comparison to compare the existing and proposed situations. In these cases we generally look around the surrounding area to find out what is an acceptable level of daylighting and try to prove that the surrounding areas do not achieve the minimum values for daylighting and sunlighting and therefore we can use these as a basis rather than the BRE Guidelines.
Another argument is that bedrooms should be viewed as less important as they are really fundamentally used for sleeping.
Where there has been consented schemes on a particular site, we have used the consented scheme as a guide to test against proposals rather than the existing situation. This is also applicable for master plans.
We regularly review the published planning appeal results, as, although they cannot be used as precedent, they can provide a good indication of what may and what may not be accepted.
If an adjoining owner has designed their building as shown in this photograph, you could argue that by creating a recessed balcony they have placed an excess burden on the adjoining site.

And lastly if all else fails we always like to go back to the fact that the BRE guidelines are just guidelines.


As previously stated, rights of light is common law rather than planning law and therefore there are certain criteria which have to be met in order for a window to receive a right of light. There are three ways generally in which an opening can obtain rights of light, these being by legal document, by prescription or by retained prescription. There are also ways to prevent a right of light being enjoyed such as by serving Light Obstruction Notices or by using powers of Section 237 of the Town & Country Planning Act.
Whenever we are asked to advise on rights of light we will always ask for the report on Title and Office Copy Entries in order to assess whether there are any restrictions. The picture below shows a building that was subject to a restrictive covenant which was only permitted to be redeveloped to a height of 80 ft and with a cut-back at an angle of around 60 degrees.

You may have seen signs like that shown below, which is simply a method used by building owners to tell the outside world that they enjoy a right of light.

Prescriptive Rights

Like other easements, a right of light can be acquired by prescription as defined in the Prescription Act 1832. In order to enjoy such rights a window, or, strictly speaking, a ‘defined aperture’ has to enjoy light for an uninterrupted period of 19 years and one day. In our experience, this is the most common way of obtaining rights of light and you can therefore assess the likelihood of any problems to a particular site by looking at the ages of the surrounding buildings with windows looking over the proposed site.
Where windows have been bricked up the owner is only deemed to have abandoned their rights of light if the brickwork is stitched into the main elevation.

This rule however is difficult to apply to the building below as it would not generally be practical to build the brickwork out from the recessed windows. It would therefore be a matter for a judge to decide whether or not the rights of light have been abandoned.

As well as reviewing the ages of the surrounding buildings to your site you must also be aware that buildings less than 20 years old could enjoy a retained prescriptive right. A retained prescriptive right can occur if the new windows to a development are in the same or similar positions to any old windows on plan and elevation.
In this scenario below it is generally accepted that a property has a retained prescriptive right of light.

Rights of Light can also be acquired by the application of the doctrine of lost modern grant.

Light Obstruction Notices

Where a building has not yet gained a right to light, allowing it to do so may hamper the redevelopment of adjacent buildings and this should always be kept in mind when advising a client on the future redevelopment of their property. The acquisition of prescriptive rights of light can be prevented by the service of a Light Obstruction Notice, which is a notional obstruction placed in front of a window. It is normally the role of a solicitor to serve a Light Obstruction Notice.

Section 237 of the Town and Country Planning Act 1990

Where rights of light have been established, a method of avoiding injunction for a breach of those rights is by utilising Section 237 of the Town & Country Planning Act. This legislation was brought in to enable local authorities to develop sites without being injuncted through the courts. The legislation states that under Section 237, the local authority has the right to override any easements enjoyed by the surrounding properties. More importantly Section 237 states that successors in Title can also utilise the powers. It is generally a rights of light surveyor or solicitor’s responsibility to identify the potential use of Section 237, but it is important to understand that protection can be gained.  Architects can sometimes give advice in this area. In fact Manchester City Council, The City of London and Southwark have been very proactive in supporting new development within their Borough in that they have discussed the possibility of taking a long term interest in a site in order to utilise Section 237. This can provide the protection to construct a proposal without fear of it being stopped by the neighbours.

Basic Theory of Rights of Light

The following principles only apply to England and Wales. It is important to note that a room does not have a right to total light and that it is entitled to an adequate level of lighting.
Where there are serious losses in light, injunctions can be served to stop a developer from building their proposal. This is of course something that every developer will want to avoid as it could be highly destructive and costly.
Case law dictates what constitutes a good level of natural lighting. It is generally accepted that residential lighting levels are of higher importance than commercial properties which is why most the case law refers to residential properties. It should also be noted that a residential property owner will be probably more passionate about the light losses to their building than a building owner to an office would be, who may let their building out to a tenant.
With regard to most rights of light problems compensation is normally an adequate remedy. The way in which this is calculated is to normally run a 3D analysis of the proposed development with the surrounding properties also modelled up in 3D.
A number of large surveying practices have bespoke software which runs this analysis and the output of which can provide the amount of square footage of light lost within an affected building. By applying some simple valuation principles they are able to provide the basic compensation figures in which to negotiate with the adjoining owners.
From land survey information they model the existing building and surrounding neighbouring properties. Using architectural plans and sections they model the proposed massing and overlay on top of the existing site.
They also model the rooms behind the neighbouring affected properties in order to calculate the minimum light level agreed, which is 1 lux at desk top height. It is important that to receive accurate information for the internal configurations as this can influence the advice given. Surveyors often try to obtain information by going to the local authority and checking the files for plans. Otherwise they sometimes pretend to express an interest if a property is up for sale or to let.
For example, our bespoke software gives an output of pools of light, the green being existing, the red the proposed and the hatched area being the light loss. We total all the light losses for a property, giving a final square foot of light loss. Using this figure we can provide a basic book value for the loss in light. See below.

Common Mistakes

Having discussed the general principles behind rights of light there are a few common mistakes. The first is that where a building is mostly glazed. Whilst it cannot be disputed that there will be some light travelling through the structure to an adjoining property, we have to count glass as an obstruction as you can not guarantee the cleanliness of the glass or indeed how much light will pass through it.
Another common mistake is that we assess the amount of light that is reflected off a property. Whilst it is a fact that there is a certain amount of light reflected from a surface, the calculations do not take in to account any reflective light and neither does it account for any artificial lighting sources.
Large overhangs and brise soleil are common place in architectural designs, however these do tend to become the leading edge of obstruction for proposed buildings. A brise soleil might well be constructed so that it allows light in at certain angles but we do have to count these as obstructions as light comes in from many angles and therefore it is likely that the brise soleil will be an obstruction to an adjoining window.
Finally, the most common problem that we have encountered is that you might think you have resolved all the lighting issues by obtaining a planning permission. However, rights of light will remain an issue as the planners are unconcerned with rights of light.

Case Studies

Case 1
The first of these is a proposed development which is marked B on the plan. This proposed development affected the daylighting to the property which is marked A on this plan.

With regard to rights of light, our advice was there was no issue as the site was compulsory purchased by the local authority as part of a road widening scheme. It was interesting to note that when the road widening had finished the site was earmarked as a future potential development site. The site was then sold on for redevelopment.
The developer therefore had protection with regard to Section 237 of the Town & Country Planning Act and would only have to pay compensation to those people who incurred light losses, rather than potentially having the development stopped with an injunction.
However this did not stop the residents of building A objecting on planning grounds. We produced a daylighting and sunlighting study which found that there were significant levels of daylighting and sunlighting loss to the properties. However the planning authority agreed with us when we argued that this site previously had buildings of similar height to the proposed development and that this site was always identified for redevelopment. Planning permission was granted in this case.

Case 2
This is interesting in that the redevelopment of this corner site conflicted between planning advice and rights of light advice. Planners are always keen to see that a corner site is developed with a strong presence. The planning authorities wanted to make this development even taller than it was designed, whereas we were advising that no further massing should be added as rights of light to the office development would be affected. This is the only case that we know of where a developer did not want to build any higher, which is very rare!

Case 3
This proposal was very interesting in that the hatched area on the plan below was protected by a restrictive covenant that allowed the owner of the site to develop a building as high as they like in that particular area.

Therefore when the developer for this site started designing they gave no regard to the light well that is marked A at the top of the plan. As you will see by the plan below the proposed development formed a reciprocal lightwell which you will see is not very big.

The problems that occurred with this site was that the building with the lightwell at the top of the plan had a change of use from a warehouse to residential flats. The owner of the development site did not object to this at the time and the windows that were within the lightwell were used to light habitable rooms.
Therefore when the proposal submitted for planning the local authority had several objections from people who had bought flats within the refurbished warehouse and planning permission was refused. Effectively this site has now been sterilised by the fact that the lightwell lights habitable rooms regardless of the rights of light deed.

Developable Envelopes

As you will see on this simplified three dimensional model we can project light lines from surrounding properties that can form an envelope in which you can design within. This does not however mean that you are totally restricted by this envelope and there are thousands of permutations in which you can lower and raise different areas around the site, just as long as they are localised. By producing such an envelope you can identify key areas around the site that have development potential and those which you really need to steer away from.


Therefore in summary, with regard to daylighting/sunlighting and rights of light issues there are three key points.
You should be wary of any neighbouring residential properties that you have around your site. You must consider daylighting and sunlighting issues with regard to planning as well as considering rights of light. Residential owners can be very passionate about light losses to their properties as normally they have invested a great deal of money in that particular property.
The second point to note is to ensure that you have considered daylighting and sunlighting issues for a planning application. Failure to show that you have made such considerations can cause the planning authority to be suspicious of the impact your development might have on surrounding buildings and therefore they might be more likely to ask for a full study to be undertaken.
Lastly and most importantly you must raise rights of light issues as early as possible as developments can be stopped with injunctions. There is little point going down the process of obtaining a planning permission only to have to resubmit a reduced scheme if rights of light were to be an issue.

Suggested reading material.

Building Research Establishment Report 1991 “Site Layout Planning for Daylight and Sunlight: A Guide to Good Practice”, by PJ Littlefair
British Standard document BS8206 Pt 2: 2008 ‘Lighting for buildings - Part 2 : Code of practice for daylighting’
Rights of Light: The Modern Law, Second Edition. S Bickford Smith, Andrew Francis with Elizabeth de Burgh Sidley and David Blundell. Published by Jordan Publishing Limited 2007
Case in Point – Rights to Light. Sarah Hannaford Jessica Stephens and Rachel O’Hagan. Published by RICS 2008
Rights of Light and How to Deal with Them. Fourth Edition. John Anstey updated by Lance Harris. Published by RICS 1998

Alastair Gill
Drivers Jonas Deloitte
Athene Place, 66 Shoe Lane, London EC4A 3BQ,
Tel/Direct: +44 (0)20 7303 3632 |
Alastair can be contacted at the above address.