Sunlight to allotments, playgrounds and open space

Sunlight to open space planning assessments use the same guidance that protects back gardens, and the test is more generous to developers than most objectors expect. BRE 209, Site Layout Planning for Daylight and Sunlight, suggests that at least half of an amenity area should receive at least two hours of sunlight on 21 March, and that a loss becomes noticeable where the sunlit area falls below about 0.8 times what it was before. Those two numbers decide most arguments about a new building overshadowing a park, a playground or a row of allotments.

Knowing them changes what an objection should say. A letter claiming that a scheme will put a play area in shadow carries little weight. A letter pointing out that the submitted sun on ground study shows the two hour area dropping from 70 per cent of the space to 40 per cent is a material point the officer has to address.

Which open spaces get assessed

BRE 209 applies its amenity sunlight advice to gardens and to a range of other outdoor spaces, including parks and playing fields, children's playgrounds, sitting out areas, allotments and outdoor swimming pools. The common thread is that people use the space in a way that depends on sun reaching the ground.

But not every green space qualifies. A verge, a landscaped buffer, a drainage basin or an area with no public access is unlikely to be assessed, because there is no amenity use to protect. Where a space has mixed character, the assessment should look at the part that is actually used, which is a point worth raising if a study averages a sunlit picnic lawn with a shaded shrub bed to produce a comfortable overall figure.

If the space is formally designated, say so in any representation. Local Green Space designation, protection as open space in the adopted local plan, or statutory allotment status all give the area a policy footing that an overshadowing argument can attach to.

The standard applied, and the date it is tested on

The assessment is normally reported as an area based figure for 21 March, the spring equinox, which sits midway between the extremes and is the date BRE 209 uses for amenity sunlight.

Two hours of direct sun on at least half the area is the suggested criterion, and the 0.8 ratio is the test for whether a reduction is noticeable. A study should present both the absolute position after development and the proportional change from the existing situation, because a space that was already poorly sunlit can pass the proportional test while failing the absolute one, or the reverse.

Many assessments also show 21 June and 21 December for context. Those are useful illustrations rather than tests, and an assessment that leads with midsummer figures is presenting its best case.

Allotments and growing space

Allotments deserve more care than general amenity space, because the use is productive rather than recreational. Vegetables need sun through the growing season, not at the equinox, so a study that reports only 21 March tells you less than it should.

Ask for the growing season position, typically April to September, and for the effect on the plots nearest the new building rather than the site average. Shading of the northernmost plots at the far end of a site is one thing. Shading the whole southern boundary is another.

Statutory allotments carry their own protection. Disposal or appropriation of land held as statutory allotments requires the consent of the Secretary of State under section 8 of the Allotments Act 1925, which is a separate hurdle from planning permission and is sometimes overlooked when a council promotes development on its own land.

Playgrounds and children's play space

Play space is assessed for sunlight on the same basis, and in practice two issues come up.

The first is which part of the space is counted. Equipped play areas are often small, and a study that assesses the whole park rather than the equipped area can mask a result where the swings sit in shadow all morning. The second is that overshadowing often accompanies a reduction in the amount of play space, particularly where a scheme proposes to build on part of an existing area.

Quantity and quality are both policy matters. A Play Space Assessment deals with provision against the standards that apply locally, while an Open Space Assessment covers the wider open space position. Where the issue is sunlight specifically, the relevant document is an Overshadowing Study.

Overshadowing by taller buildings

Tall buildings produce long shadows that move quickly, and that is both the problem and the defence. A twenty minute sweep of shadow across a park in late afternoon is a different effect from a permanent shaded strip along the southern edge, and the assessment should show which it is.

Transient shadow diagrams at hourly intervals are the usual output. Read them with the sun path in mind: shadows fall north of a building at midday in the northern hemisphere, so a building on the southern boundary of a space does the most harm and a building on its northern boundary usually does none.

Where several schemes are coming forward in the same area, the cumulative picture matters more than any one building. Ask whether consented but unbuilt schemes were included in the model, because a study against the existing context alone can understate the eventual position. The note on what to include in daylight modelling outputs sets out the minimum a reader needs to check that for themselves.

Replacement provision where sunlight is lost

Planning rarely treats sunlight loss to open space as a standalone reason for refusal. It is weighed with everything else, which means the realistic objective for an objector is usually mitigation rather than refusal.

Mitigation that councils have accepted includes reshaping or stepping the building down towards the space, relocating the most sun dependent uses within the open space, enlarging the area to compensate for a shaded strip, improving the quality of the remaining space, and planting or layout changes that make the sunlit part more usable. None of those is guaranteed, and all of them are easier to secure before the application is determined than afterwards.

How to use the evidence as an objector

Work from the submitted documents rather than from impression.

1. Find the sunlight or overshadowing study in the application documents and read its stated method and assumptions.
2. Check the boundary of the area assessed against the part of the space people actually use.
3. Note the 21 March two hour figures before and after, and work out the ratio.
4. Check whether existing trees, boundary structures and consented schemes were modelled.
5. If the space is designated, cite the policy that protects it alongside the sunlight figures.
6. Put the point in writing within the consultation period, in one page, with the numbers at the top.

An objection built that way gets a reasoned response in the officer's report. A general complaint about loss of light usually gets a single sentence.

If you are on the other side of the counter and preparing the submission, browse the report types to see which open space and sunlight documents a council is likely to expect.