Daylight and sunlight reports for London planning applications
When a neighbour objects that your extension will block their light, or your council's validation list asks for an assessment, the answer is a daylight and sunlight report. It measures the effect on neighbouring windows and gardens against the published BRE guide. A specialist we coordinate prepares it from your drawings for a fixed £895.
Fixed fee from £895 · all prices
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What the assessment is based on
Councils commonly test daylight against one document: the Building Research Establishment's guide, Site layout planning for daylight and sunlight (BR 209), now in its third edition of 2022. It is guidance, not law: the guide describes itself as purely advisory, with numerical targets that may be varied. Planning officers still use it as the starting point.
That is why a report matters when a neighbour objects. An officer cannot weigh 'it will make my kitchen darker' against your drawings. They can weigh a calculation that says what the neighbouring window receives now, what it receives afterwards and how that compares with the guide.
Daylight and Sunlight Reports
from £895
Every price is the full fixed fee you pay. No VAT is charged. Council application fees are paid to the council separately.
What you get
- A 3D model of your scheme and the surrounding buildings built from the drawings
- Vertical sky component and no-sky-line tests on neighbouring windows
- Sunlight tests to windows and an overshadowing check on gardens
- A written report setting out the results against the BRE criteria
- Plain-English conclusions and, if a window fails, what could reduce the loss
- The report as a PDF to submit with your planning application
- Gather the facts
Your drawings, our survey and the neighbours' building heights and window positions.
- Build the model
Existing and proposed massing in 3D, with every neighbouring window that could be affected.
- Run the BRE tests
Skylight, daylight distribution, sunlight and garden overshadowing, before and after your scheme.
- Read the results
Which windows lose light, by how much, and whether the loss is likely to be noticeable.
- Report and options
A document for the planning officer, and a note of design changes if a result is poor.
The main test: vertical sky component
Vertical sky component, or VSC, measures how much sky can be seen from the middle of a window. The guide says that if the VSC is greater than 27% then enough skylight should still be reaching the window. If it is both less than 27% and less than 0.80 times its former value, occupants will notice the reduction in the amount of skylight.
Read that carefully, because it is the point most often misunderstood. A window below 27% is not a failure. It fails the test only if it also drops by more than a fifth against its present value. In a dense London street many windows start below 27%, so the question is the proportion of light lost, not the absolute figure. A companion test, the no-sky line, checks how much of the room still sees the sky.
Under section 3 of the Prescription Act 1832, once light to a building has been enjoyed for the full period of twenty years without interruption, the right to it becomes absolute, unless it was enjoyed by consent given in writing.
Sunlight and gardens
Sunlight is tested separately on windows facing within 90 degrees of due south, using annual probable sunlight hours. The guide says a room that can receive more than one quarter of annual probable sunlight hours, including at least 5% in the winter months, should still receive enough sunlight. Losses are only likely to be noticeable if the hours fall below that and below 0.80 times their former value.
Gardens have their own rule. The guide recommends that at least half of a garden or amenity area should receive at least two hours of sunlight on 21 March, and that a loss is likely to be noticeable if the area that does so falls below 0.80 times its former value. For a tall extension at the end of a short terraced garden, that overshadowing test is often the one that matters.
Do you need one?
Not every extension does. Not every extension needs a full report. A council may ask for one only on larger schemes or where a neighbour's window sits close to the new wall, so check your council's local validation list and any pre-application advice. Sometimes a simpler check on the plans is enough, and where it is, we say so instead of selling you the full report.
If you are in doubt, send us the drawings. We tell you whether a quick check is likely to satisfy the officer or whether the full assessment is the safer course, and if it is, we commission the specialist and coordinate the model with our drawings so both agree.
Daylight is not the same as a right to light
A planning daylight report does not deal with the private right to light, which is a separate legal matter between neighbours. Under section 3 of the Prescription Act 1832, once light to a building has been enjoyed for the full period of twenty years without interruption, the right to it becomes absolute, unless it was enjoyed by consent given in writing.
A scheme can pass the planning test and still infringe a neighbour's right to light. The two measures are different, and a right-to-light survey is a different piece of work. We tell you when your scheme sits close enough to a neighbour's windows to need a solicitor's view as well.
Who prepares it, and what it costs
The report is prepared by a specialist daylight consultant we coordinate. We do not do the calculations ourselves, and we make no claim to. What we do is give the specialist a clean drawing set and a survey, check that the model matches your scheme and put the result in the application.
The fixed fee is £895, the total you pay, with no VAT charged. It does not include the council's application fee, a right-to-light survey, or a redesign if the results show a problem. If the results suggest changes, our rear extension drawings service redraws the scheme and the report is rerun.
Sources
Every figure on this page, where it comes from and a link to the original.
| Figure | Source | Link |
|---|---|---|
| 2022 | BRE, Site layout planning for daylight and sunlight (BR 209), title page (source wording: "Third edition 2022") | www.bcpcouncil.gov.uk |
| 27% | BRE BR 209 (2022) para 2.2.7: (source wording: "If this VSC is greater than 27% then enough skylight should still be reaching the window of the existing building") | www.bcpcouncil.gov.uk |
| 0.80 times its former value | BRE BR 209 (2022) para 2.2.7: (source wording: "both less than 27% and less than 0.80 times its former value, occupants of the existing building will notice the reduction") | www.bcpcouncil.gov.uk |
| one quarter of annual probable sunlight hours | BRE BR 209 (2022) para 3.2.6: (source wording: "more than one quarter of annual probable sunlight hours (APSH), including at least 5% of APSH in the winter months between 21 September and 21 March") | www.bcpcouncil.gov.uk |
| two hours of sunlight on 21 March | BRE BR 209 (2022) para 3.3.17: (source wording: "at least half of a garden or amenity area should receive at least two hours of sunlight on 21 March") | www.bcpcouncil.gov.uk |
| twenty years | Prescription Act 1832 s.3: where light has been enjoyed (source wording: "for the full period of twenty years without interruption, the right thereto shall be deemed absolute and indefeasible") | www.legislation.gov.uk |