Daylight and Sunlight Assessments in Barnet

Barnet gives us a wider spread of work than almost any other London borough. In Hendon, Golders Green and Finchley it is usually a roof-top addition to an inter-war block of flats or a mansion-block conversion, where the question is sunlight to the gardens behind. In Totteridge, Mill Hill and Hadley it is more often a replacement house on a large plot, where the new building is bigger than the one it replaces and the neighbours on both sides want to know what that means for their windows. Along the Edgware Road, in Colindale and Burnt Oak, it is permitted-development conversions of offices and shops into flats, where the council cannot ask about the neighbours but must be satisfied that the new rooms get adequate natural light.

Barnet adopted a new Local Plan in March 2025, and it expects a daylight and sunlight assessment wherever there is a potential significant adverse effect on the light adjoining properties currently enjoy. Contested schemes go to committee, and that is where the three jobs below come in: one with a day to spare before a committee meeting, one fitted into a fast-track resubmission, and one where the only fix available was to change the room, not the window. If you are new to all this, our main daylight and sunlight assessment page explains what a report contains.

Recent daylight and sunlight assessments in Barnet

Whiteways, Hillview Gardens, Hendon, NW4: a sunlight study for a committee

Two new storeys on an existing block of flats in Hendon, creating nine flats, with a side extension for a new staircase. During consultation a resident raised loss of sunlight to a neighbouring garden on higher ground, and the application was heading to committee. We ran the BRE sun-on-ground test and a shadow study for that garden: the proposal kept it within the guidelines, with the change marginal against the existing roof and vegetation.

The application, 24/3025/FUL, went to committee on 1 April 2025 and was approved subject to conditions on 23 April 2025.

Barnet House, Barnet Lane, Totteridge, N20: re-testing a redesigned house

We had assessed an earlier version of this replacement house. When the architects redesigned it, the planning consultant assembling the pack needed the neighbour-impact report brought up to date with the new massing. Rather than start again, we placed the new design into the existing context model, re-tested the neighbouring windows and gardens, and updated the appendix when the west elevation material changed.

The application for demolition of the existing house and a new two-storey detached dwelling, 25/2045/FUL, was approved subject to conditions on 15 July 2025.

Edgware Road, Colindale: an internal daylight assessment for a permitted-development conversion

A repeat developer client needed internal daylight evidence for converting the upper floors of a building on the Edgware Road into three flats under permitted development. No new or enlarged windows were possible, which rules out the usual remedies. Two of the three flats met the daylight target; the third-floor living, kitchen and dining room fell well short. With the windows fixed, we advised reducing the area of that room so that the daylit proportion met the threshold. The report was issued on the amended layout for the client's prior approval submission.

What Barnet planning officers look for

Barnet's approach to daylight and sunlight is set by the Barnet Local Plan, adopted in March 2025. Its design and amenity policies require development to protect the amenity of neighbouring occupiers, including their access to daylight and sunlight, and daylight and sunlight assessments are expected for all applications where there is a potential significant adverse effect on the levels currently enjoyed by adjoining properties. Officers apply the BRE guidance BR 209: Site layout planning for daylight and sunlight (2022 edition).

For householder applications such as extensions, conversions and roof alterations, Barnet's Residential Design Guidance SPD sets out how those policies are applied. You can find the adopted Local Plan at barnet.gov.uk/planning-policies-and-local-plan and the residential design guidance at barnet.gov.uk/design-guidance. For conversions under Class MA and the other permitted-development routes, the prior approval test is adequate natural light in the new habitable rooms, so the evidence is an internal daylight assessment rather than a neighbour study.

When you need an assessment in Barnet

• Roof-top and upward extensions to blocks of flats in Hendon, Golders Green and Finchley, where the gardens behind are the usual concern
• Replacement or substantially enlarged detached houses in Totteridge, Mill Hill, Hadley Wood and Arkley, where the new building is wider and taller than the old one
• Side extensions to 1930s semis in Edgware, Burnt Oak and East Barnet that bring a two-storey flank wall closer to the neighbour's windows
• Permitted-development conversions of offices and shops along the Edgware Road, in Colindale and in North Finchley, which need an internal daylight assessment for prior approval
• Backland and garden-plot houses in Whetstone and Friern Barnet with neighbours on three sides
• Any application that has drawn a consultation response on loss of light, especially if it is heading to committee

How we work

We model your scheme and its neighbours in 3D from your drawings, mapping data and photographs, run the BRE tests and tell you the results before the report is written, so there is time to adjust the design if anything falls short. The fee is fixed and agreed up front; the report usually takes 4–5 working days from final drawings, and we can move faster for a committee deadline. The four tests are:

• Vertical Sky Component (VSC): the amount of sky a neighbouring window can see
• No-Sky Line (NSL), or daylight distribution: how far daylight reaches into the room
• Annual Probable Sunlight Hours (APSH): annual and winter sunlight to windows facing within 90 degrees of south
• Sun on ground: whether at least half of a garden still gets two hours of sun on 21 March

Each test is explained on our VSC, NSL and APSH page, and the thresholds on our BRE guidelines page.

Frequently asked questions in Barnet

A neighbour has objected about their garden. Does Barnet need a full windows study?

Not necessarily. If the concern is sunlight to a garden, a sun-on-ground test and a shadow study answer it directly, as they did at Hillview Gardens. We will tell you when a narrower report is enough and when the officer is likely to want the windows tested too.

Do permitted-development conversions in Colindale need daylight evidence?

Yes. Adequate natural light to habitable rooms is one of the prior approval matters for Class MA and similar conversions, and Barnet checks it. The assessment is internal only, and because you cannot add windows the fix is usually in the layout.

We have redesigned since the last report. Do we start again?

Usually not. If we built the original model, the new massing is dropped into it and only the affected results are re-run, which is why the Totteridge update took two days rather than a week.

Get a fixed-fee quote

Send drawings through our contact page or price the job yourself with the price calculator. Call Nick on 01962 809155 or email nick@sunlightassessments.co.uk. For sites across the border in Enfield, see our Enfield page.