Daylight & Sunlight Matters for those Planning an Extension or New Build

No matter the size, any new project requires a lot of planning. Whether extending your home or starting a new build from scratch, it’s important to discuss your the massing of your scheme, and it’s potential impact on your neighbours with your designer.

Many Local Authorities have policies in place to ensure access to daylight and sunlight to neighbouring habitable room windows. They can also check sunlight to the neighbour’s principal garden is not adversely affected by a development.

Even in the absence of such a specific local policy, National Planning Policy stipulates that amenity should be considered in the planning of any development.

In cases where the local councils’ policies are not clear on the issues of Daylight and Sunlight, failure to assess can still lead to conflict. A neighbour may challenge a planning decision if proper consideration has not been given.

The most widely recognised and used document for assessing good Daylight and Sunlight design is “Site Layout Planning for Daylight and Sunlight – A Guide to Good Practice, 2nd Edition” by Paul Littlefair. It is a nationally recognised publication, formally known and still widely referred to as BRE 209. Whilst not mandatory, it has been adopted by many design practitioners, planning consultants and Local Authority Planning Departments throughout the UK.

Failure to meet the tests in BRE 209 can cause complications for any proposed extension or build. If you’re deemed to be causing an adverse impact on your neighbour’s home, planning permission can be refused. However, you may be asked to adapt your design to eradicate the harmful effect on your neighbour’s property.

You may be asked to demonstrate that your design will not adversely affect your neighbour(s) by providing a Daylight and Sunlight Assessment to accompany your planning application.

If this does happen, we can help.

Daylight and Sunlight – Things to remember when building an extension or new build

  • This is a Town and Country planning issue
  • Sunlight and daylight are both considered an amenity of adjacent occupiers, not a right.
  • Windows to bathrooms, stores and garages need not be analysed
  • The planning officer takes the impact on daylight and sunlight amenity into consideration. However, planning permission may still be granted even if the development affects adjoining occupiers’ amenities.

Rights To Light – Things to remember when building an extension or new build

  • Rights to light are an easement, similar to a right of way over a neighbour’s land or building.
  • Rights to light are not a planning consideration, and can be enforced even if planning permission is granted.
  • Right to light is normally obtained by enjoying the light uninterrupted and without permission for 20 years.
  • An ‘adequate’ amount of light is the equivalent of the amount of light one foot away from a candle.
  • If the amount of ‘adequate’ light in the room is reduced below 50-55% of the area because of the development, then the loss of light is considered actionable in court.
  •  Sunlight, artificial lighting, reflected light internally or externally are not considered in the analysis.

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“Following a rejection of our plans for the building of a new house, by the Planning Authority, due to the effect of the proposed development upon the living conditions of the neighbouring properties, with particular regard to outlook and daylight / sunlight, we decided to appeal the decision. As part of our appeal we commissioned a Daylight & Sunlight Assessment from Smith Marston which reached an entirely different conclusion to the planning authority. The report was crucial, with the Planning Inspector concurring with it’s conclusions, and the decision of the planning authority overturned. We found the work undertaken by Smith Marston excellent, objective and in accordance with Industry standards, and would have no hesitation in recommending them.”

Mr Brown
“Smith Marston helped us gain planning approval on our two-storey extension after a number of objections from neighbours. The advice they gave and the detailed letter to the council gave factual information to dismiss unfounded objections.”
Mr A, Warrington

“A Local Authority Planning Officer required confirmation that a proposed housing development would not cause any loss of sunlight to an adjacent property. On this basis Smith Marston completed a BRE garden sunlight test which on completion satisfied the planning officers concerns. This specialist report proved to be invaluable in securing the planning approval for our client.”

Keith Butler, KB Design

Frequently Asked Questions

From a planning perspective, these would not be considered by the local authority as the areas are classed as ‘non-habitable’. However, such areas CAN have a legal right to light, meaning even if you get planning permission, you could potentially cause a legal injury to your neighbour’s home. This type of extension causes the most common legal rights to light problems we come across, so the risk should not be ignored.
Of course. We can take your architect’s drawings and prepare a 3D computer model to calculate how much daylight and sunlight your neighbours will enjoy pre and post-development. We can also ascertain how many sunlight hours your neighbour’s garden will be able to receive. If the outcome will cause problems with your neighbours or hinder your chances of gaining planning approval, we can help. We will redesign the ‘mass’ of your proposal by calculating the amount of ‘cutback’ you would need to undertake.

Not really. There are genuine times when such studies are necessary, and these are when the ‘rules of thumb’ tests fail. In your case, the drawings show that your new extension does not cut through a line drawn at 25 – degrees from the horizontal plane from the centre of your neighbour’s window.

Therefore, the 25-degree rule of thumb test is not breached, and there would be no risk to your neighbour’s windows. In your case, the neighbour’s windows are ‘non-habitable’, which do not require consideration. In situations like this, we have written to the Local Authority to explain that a study should not be necessary to retract the request for such a report. Many Local Authorities will do this if we can demonstrate why there is no risk. Unfortunately, the request you have received may have stemmed from a ‘tick-list’ approach by somebody in the Validation team, without careful thought having been given as to whether such a report is necessary.

Unfortunately, this is quite common. Whilst more common to consider the impact of a new scheme on a neighbouring property, Planning officers can also view the availability of daylight and sunlight to a proposed scheme. We have had several projects where planning officers have ‘felt’ a new dwelling would be poorly lit and have been minded to refuse consent. Some have even refused consent and forced the applicant to go to Appeal. A ‘Within’ Daylight and Sunlight Assessment could be invaluable for you in these situations. If a planning committee (or Planning Inspectorate at Appeal) is faced with considering the ‘gut instinct’ of a planning officer versus a professional study, based upon computer modelling and adopting widely accepted, industry measured criteria; the latter puts you in a much stronger position.

Technical Information on Daylight & Sunlight

A neighbour to a proposed development may have grounds to object within the planning process based upon loss of daylight and sunlight.

In such circumstances, a neighbour wishing to object to a proposed development may wish to add some weight to this objection by arranging for a formal assessment to demonstrate whether the scheme would fail the tests described within the BRE document. Although there may be overriding factors which would still lead a Council’s planning department to grant planning permission despite the failure of the scheme in respect of the BRE guidance tests, this is a serious ‘material consideration’ matter which could give grounds for refusal of an application for planning permission.

More Details

When considering the impact on neighbours’ sunlight, there is a test that considers the hours of sunlight a window will receive over a 12 month period. Because the test relates only to sunlight, only windows facing within 90 degrees of due south are considered under the methodology contained with the BRE document Site Layout Planning for Daylight & Sunlight.

The guidance is that main windows should receive at least 25% of the ‘annual probable sunlight hours’ for a 12 month period. This should include 5% of the total probable sunlight hours over the winter months between 21 September and 21 March.

As for the Legal Right to Light, this takes no account of direct sunlight and assesses only the amount of diffuse light within a room related to an affected window.

The principal method of assessing this is a measure of the amount of sky visible from the window of an affected room. This assessment component is called the Vertical Sky Component (VSC). For a window of a room to be adversely affected under the BRE guidance, the window must have a view of less than 27% of the ‘dome of the sky’ (a VSC of less than 27%) and the VSC must be less than 0.8 times its previous value.

When assessing daylight inside proposed new buildings, prior to June 2022, there used to be a detailed assessment called the Average Daylight Factor. This was a measure of the actual likely natural diffuse daylight in a room taking account of various matters influencing this such as the reflectivity of surfaces and the glazing in the window. The no sky-line was a measure of those parts of the room which have no view at all of the sky at all. These former tests were laid out in the 2nd edition of the BRE Guide. In early June 2022, the 2nd Edition of the BRE Guide was updated to the 3rd Edition.

This includes new daylight factor tests for levels of daylight inside new developments. In domestic houses in the UK, the minimum levels of light requirements to bedrooms are 100 lux, 150 lux to living rooms and 200 lux to kitchens.

The BRE guidance suggests that consideration of sunlight to external areas should normally include:

  • Gardens, usually the main back garden of a house, and allotments;
  • Parks and playing fields;
  • Children’s playgrounds;
  • Outdoor swimming pools and paddling pools;
  • Sitting-out areas, such as those between non-domestic buildings and in public spaces;
  • Focal points for views, such as a group of monuments or fountains.

The BRE guide recommends that at least half of the garden/amenity area should receive at least two hours of direct sunlight on 21 March.