Daylight and Sunlight Assessments in Kensington and Chelsea

In the Royal Borough most of our instructions involve the rear of a terrace: an extra storey on a rear closet wing in Chelsea, a loft and roof terrace on a stucco house in Earl's Court, or a basement with a lightwell in Notting Hill and Holland Park. The houses are tall, the gardens are narrow, and the windows opposite are close, so a modest-sounding extension can have a measurable effect on a neighbour's bedroom or kitchen. RBKC's officers know this and will ask for a daylight and sunlight assessment with the application rather than after it.

The borough also has some of the most engaged neighbours in London. A good share of our Kensington and Chelsea work is responding to comments made during consultation: re-checking window positions, testing an amended design, and giving the architect a clear written view on which points have technical merit under the BRE guidelines. Reports usually take 4–5 working days; amendments are turned round faster.

Recent daylight and sunlight assessments in Kensington and Chelsea

49 Radnor Walk, SW3 – first and second floor rear extension

A first and second floor rear extension to a terraced house in Chelsea, adding an en-suite and a bedroom. RBKC asked for a daylight and sunlight assessment, and during consultation neighbours raised concerns about loss of light. The design was amended with a 300 millimetre set-back and a railing in place of a solid parapet. On the amended design every tested window on Radnor Walk and Smith Terrace met the BRE guidelines; the nearest front-room window kept more than 90 per cent of its former daylight and sunlight.

RBKC granted planning permission on 29 April 2026 (PP/25/04860).

Flat A, 15 Kenway Road, SW5 – loft extension with front roof terrace

An architect instructed a neighbour impact report for a loft extension creating additional living space with a front roof terrace on a flat in Earl's Court. When the design changed after our first report, the application needed an assessment that matched it, so we re-tested the revised top floor against the neighbouring windows and reissued the report on the amended design.

RBKC granted planning permission on 28 January 2025 (PP/24/07929).

What Kensington and Chelsea planning officers look for

RBKC determines applications against its Local Plan 2024, adopted on 24 July 2024, read with the London Plan. The plan places weight on protecting the amenity of existing residents, including their access to natural light, which matters in a borough of tightly spaced terraces and mansion blocks. For the numbers, the council applies BRE BR 209, Site layout planning for daylight and sunlight (2022 edition). Much of the borough is within conservation areas, and extensions to listed or locally significant buildings are examined closely, so an officer will usually want the daylight evidence in the submission rather than requested later.

The Basements SPD (adopted 2016) is directly relevant where a lightwell or the removal of below-ground structures changes the light to a neighbour's lower ground floor, and the council's wider design guidance expects development to protect, and where possible improve, the amenity of neighbouring occupiers. RBKC's planning policy pages are at rbkc.gov.uk/planning-and-building-control/planning-policy, the Local Plan 2024 at rbkc.gov.uk/planning-and-building-control/planning-policy/local-plan and the SPDs at rbkc.gov.uk/planning-and-building-control/planning-policy/supplementary-planning-documents-and-guidance.

When you need an assessment in Kensington and Chelsea

• Raising a rear closet wing by one or two storeys on the terraces of Chelsea, Brompton and South Kensington, where the neighbour's half-landing and rear windows sit close to the new brickwork.
• A loft extension or roof terrace to a stucco terrace in Earl's Court, Kensington or Notting Hill, where a new parapet or dormer faces windows across the garden.
• A basement with a new lightwell in Holland Park, Notting Hill or Kensington, where RBKC's Basements SPD applies and the neighbour's lower ground floor windows may be affected.
• Any application on which neighbours have raised concerns about loss of light, where the officer wants independent evidence before deciding.
• Mews house roof alterations in the borough's conservation areas, where the opposite elevation is only a few metres away.
• Small flatted schemes in North Kensington, Golborne and Earl's Court where both neighbour impact and internal daylight to the new homes need to be shown.

How we work

We model the site and its neighbours from the drawings, photographs and survey data, run the BRE tests and send a report with results, marked-up plans and a plain conclusion. The fee is fixed and agreed up front, the report usually takes 4–5 working days, and if the design changes during consultation we update the same model rather than start from scratch. The four tests are:

• Vertical Sky Component (VSC) – the sky visible from a neighbouring window, before and after.
• No-Sky Line / daylight distribution (NSL) – how far daylight reaches into the neighbour's room.
• Annual Probable Sunlight Hours (APSH) – direct sunlight to windows within 90 degrees of south, over the year and in winter.
• Sun on ground – the share of a garden or terrace that receives two hours of sun on 21 March.

Our VSC, NSL and APSH page explains each test, our guide to the BRE guidelines covers the thresholds, and our daylight and sunlight assessment page describes the service.

Frequently asked questions in Kensington and Chelsea

Neighbours have commented on my RBKC application. What can you do?

We re-check the model against the points raised, test any amendment the architect proposes and give you a written technical note the agent can submit. At 49 Radnor Walk that meant verifying window positions from new photographs and testing a 300 millimetre set-back within three days.

Does RBKC ask for a daylight report with every rear extension?

Not every one, but for extensions at first floor and above on the borough's terraces it is common for the validation or pre-application response to ask for one, and it is quicker to include it than to have it requested mid-application.

Does a basement lightwell need a daylight and sunlight assessment?

If the lightwell changes the ground or walls facing a neighbour's lower ground floor window, yes. The Basements SPD expects the effect on neighbouring amenity to be shown, and a BRE assessment is the standard way to do it.

Across the border, our Westminster page covers similar terraces and mansion blocks.

Get a fixed-fee quote

Send the drawings and the address via our contact page or use the price calculator for an instant figure. Nick is on 01962 809155 and nick@sunlightassessments.co.uk.