Daylight and Sunlight Assessments in Westminster

Westminster is where the gap between buildings is smallest and the planning history is longest. The schemes we assess here are mostly mansard roof extensions on the stucco terraces of Pimlico, Bayswater and Maida Vale, alterations to mews houses in Mayfair, Marylebone and Belgravia where the facing building is a few metres away, and Class MA conversions of ground-floor shops in Notting Hill and Paddington into flats. Many of the neighbouring windows already receive well under the BRE's 27% VSC before anything is built, which changes how a report has to be written.

Westminster's case officers are precise about scope. On the Mayfair mews below the council named particular neighbouring rooms it wanted daylight distribution tested in, not just the windows; in Pimlico the officer asked for the report mid-application and listed seven neighbouring properties. Reading the officer's wording carefully, and modelling exactly what has been asked for, is most of the job in this borough.

Recent daylight and sunlight assessments in Westminster

5 Market Mews, Mayfair, W1: mansard extension and lift to a mews house

A third-floor mansard roof extension and a domestic lift to a mews house, with the council interested in the daylight to 30 Shepherd Street and to 4–6 and 8 Market Mews. In a mews the facing elevations are only metres apart, and the council asked for daylight distribution inside specific neighbouring rooms as well as the usual window tests. All tested windows met the VSC and APSH guidelines and the specified rooms met the daylight distribution test, with no design change needed. 3D-rendered window maps showed the officer which window each result referred to. Application 24/03443/FULL was permitted on 18 October 2024.

147 Cambridge Street, Pimlico, SW1V: mansard extension to a top-floor flat

A mansard roof extension to a flat on a Pimlico terrace, where the case officer asked for a daylight and sunlight report covering seven neighbouring properties while the application was under consideration. With little public planning data for the surrounding buildings, window positions were inferred from street and aerial imagery and confirmed with the architect before the report was finalised. Every neighbouring window tested met the BRE daylight and sunlight guidelines. The report was issued on 6 November 2024 and application 24/04120/FULL was permitted on 15 November 2024.

16 Needham Road, Notting Hill, W11: Class MA shop to flat

A Class MA prior approval to convert a ground-floor shop to a two-bedroom flat, combined with the existing basement flat. Only floor plans were available, with no elevations. Under Class MA elevations are often unnecessary and only the ground-floor habitable rooms needed testing, so we took the window sizes from street photography and built the surroundings from 3D mapping, with no survey needed. Application 26/07268/P3JPA was validated on 23 October 2026 and is currently with the council.

What Westminster planning officers look for

Westminster determines applications against the City Plan 2019 to 2040, adopted in April 2021 with a partial review adopted in January 2026. Its design and amenity policies require new homes to have sufficient daylight and sunlight for their context and development to protect the amenity of neighbouring occupiers. The council uses BRE 209, Site layout planning for daylight and sunlight (2022 edition), as its starting point, but it acknowledges that in the dense and historic parts of the city the BRE figures cannot always be met in full, and results are weighed in their local context. That is why a Westminster report has to say what a window receives today, not only how much it loses.

For extensions, roof alterations and loft conversions the council's supplementary planning documents and householder guidance explain how the policies apply, and officers will often name the neighbouring rooms or properties they want covered. Westminster's planning policies are at westminster.gov.uk/planning-building-control-and-environmental-regulations/planning-policy/westminsters-planning-policies and the SPDs and guidance at westminster.gov.uk/planning-building-control-and-environmental-regulations/planning-policy/supplementary-planning-documents-and-guidance.

When you need an assessment in Westminster

• Mansard roof extensions on the terraces of Pimlico, Bayswater, Maida Vale and Marylebone, where the rear windows of several neighbouring flats look onto the new roof
• Alterations to mews houses in Mayfair, Belgravia and Hyde Park Estate, where the facing elevation is a few metres away and the council may name specific rooms to test
• Class MA conversions of ground-floor shops to flats in Notting Hill, Paddington and Queensway, which turn on adequate natural light to the new rooms
• Rear extensions and infill at lower-ground level in Belgravia and St John's Wood, where lightwells and basement rooms are affected
• Any application where the case officer has written mid-application asking for a daylight and sunlight report

How we work

Send us the drawings and photographs and we build the 3D model of your building and its neighbours ourselves, with no survey needed in most cases. The fee is fixed and agreed before we begin and a report usually takes 4–5 working days. Where the officer has named particular properties or rooms, we scope the report to that wording. The service is described on our daylight and sunlight assessment page. Every neighbour report covers the four BRE tests:

• VSC for daylight at each facing window, reported before and after
• NSL for daylight distribution within named rooms
• APSH for annual and winter sunlight to windows within 90 degrees of south
• Sun on ground for gardens and courtyards on 21 March

For Class MA and other new homes we test natural light to each habitable room. See our VSC, NSL and APSH and BRE guidelines pages for the detail.

Frequently asked questions in Westminster

The windows opposite my mews house already get very little light. Does that mean my scheme cannot work?

No. BRE 209 looks at the change, so a window keeping 80% of a low starting value is within the guideline, and Westminster's own policy recognises that dense historic streets are judged in context. Our report states both the existing value and the retained proportion so the officer has the full picture.

I only have floor plans for a Class MA application. Is that enough?

Usually, yes. For a ground-floor shop conversion we can take window sizes from street photography and build the surroundings from 3D mapping, as at Needham Road, so elevations and a survey are rarely needed.

Westminster has asked for daylight distribution in specific rooms. What does that involve?

It is the no-sky line test applied inside the room the council has named, showing how much of the floor area can see sky before and after. We need the room layout, which we can usually take from the neighbour's own planning history.

Get a fixed-fee quote

Send your drawings through our contact page or get an instant figure from the price calculator. Call Nick on 01962 809155 or email nick@sunlightassessments.co.uk; for sites across the boundary in Bloomsbury or Camden Town, see our Camden page.