Open space and play space contribution formulas

An open space contribution formula multiplies three things: the number of people your scheme is expected to house, the area of open space the adopted standard allows each of them, and a cost per square metre for providing and maintaining it. Every argument about the figure is an argument about one of those three inputs. Get the population yield checked before you challenge the rate, because that is where most of the error sits.

Where the standards come from

Local standards sit in the adopted local plan, usually supported by an open space assessment carried out for the plan and an SPD that turns the policy into arithmetic. The national guidance expects authorities to base their standards on an assessment of local need rather than importing a national figure.

In practice most English authorities still anchor their quantity standards to the long-established benchmark of around 2.4 hectares of outdoor space per 1,000 population, split between outdoor sport and children's play and informal space. Some have moved away from it after their own assessment. Some have kept it and added accessibility and quality standards alongside.

Read three documents before you model anything. The policy itself, because it sets the trigger and the tenure of the obligation. The SPD, because it holds the formula. And the authority's most recent open space assessment, because it records which typologies are already in deficit in your ward, and a deficit changes the answer from a payment to on site provision.

An Open Space Assessment submitted with the application should engage with those three documents directly rather than describing open space in general terms.

Population yield and the assumptions inside it

Population yield converts dwellings into people. Authorities publish an occupancy figure per dwelling type and bedroom count, usually derived from census household size data for the district.

Two assumptions inside that conversion are worth testing.

The first is whether the authority applies bedroom-based yield or a flat rate per dwelling. A flat rate penalises schemes with a high proportion of one and two bedroom flats, sometimes heavily, and many SPDs allow bedroom-based calculation if you ask for it.

The second is whether the yield counts children separately. Play space standards are expressed per child, so the child yield is a distinct calculation and it varies sharply by dwelling mix. A scheme of 60 one-bedroom flats generates almost no child yield, and an authority applying an average household figure across the whole scheme will overstate it.

Ask for the calculation sheet. Authorities generally provide it, and the arithmetic is often carried forward from an older version of the SPD with the occupancy figures unchanged since the last census.

On site provision or a payment

The default position in most policies is on site provision where the scheme is large enough to deliver usable space, and a financial contribution where it is not. The threshold is local and it is usually expressed as a number of dwellings or a site area.

Small fragments of on site open space are worth avoiding. A 150 square metre grassed triangle satisfies an arithmetic test, serves nobody, and produces a maintenance liability that will sit on the management company for the life of the estate. Where the adopted standard would generate something of that size, argue for a payment instead and say why.

Play space age bands and the areas they need

Play space standards are age-banded, and the terminology is consistent enough across authorities to be worth learning.

• A local area for play serves the youngest children close to home, with an activity zone of around 100 square metres and a walking distance of about 100 metres.
• A local equipped area for play serves children who can travel a short distance alone, with an activity zone of around 400 square metres, equipment, and a walking distance of about 400 metres.
• A neighbourhood equipped area for play serves older children and young people, with an activity zone of around 1,000 square metres, a mix of equipment and hard surfacing, and a walking distance of about a kilometre.

Each carries a buffer zone between the activity zone and the nearest dwelling, which grows with the size of the facility. That buffer is the dimension that catches layouts, because it is measured to the habitable room window and it cannot be landscaped away.

In London the approach is different again. The London Plan sets a play provision standard expressed per child rather than per dwelling, and boroughs apply the Greater London Authority population yield calculator to establish the child yield. A Play Space Assessment for a London scheme has to work through that calculator rather than a local occupancy table.

Equipment specification follows BS EN 1176 and BS EN 1177, and the surfacing standard drives a surprising share of the cost. Budget for it separately rather than as a percentage uplift.

Maintenance commuted sums

Where the authority will adopt the space, it will ask for a commuted sum to maintain it. The sum is normally an annual maintenance cost multiplied by a period, and the period varies between authorities from around ten years to in perpetuity expressed as a capitalised figure.

Three points are negotiable and frequently un-negotiated. The maintenance specification, because a wildflower meadow cut twice a year costs a fraction of amenity grass cut sixteen times. The period, because an authority asking for 25 years should be able to say why. And the treatment of inflation, since a sum already capitalised at a discount rate should not then be indexed as well.

The same logic applies to estate roads and drainage, where the adoption route and its commuted sum follow a parallel process, covered in the note on section 38 adoption and the commuted sum negotiation.

Testing a formula against the statutory tests

Regulation 122 of the Community Infrastructure Levy Regulations 2010 requires every obligation to be necessary to make the development acceptable in planning terms, directly related to the development, and fairly and reasonably related in scale and kind. A formula does not satisfy those tests on its own. The authority still has to apply them to your scheme.

Four challenges work when the facts support them.

1. The contribution funds a facility your occupiers could not reach, so it is not directly related.
2. The ward already exceeds the adopted quantity standard for that typology, so the provision is not necessary.
3. The yield figure double counts, for example by charging for both amenity space and informal open space over the same population.
4. The levy already funds the same item, in which case the contribution duplicates it.

That last point needs care. The restriction on pooling more than five obligations towards a single infrastructure item was removed in September 2019, and authorities now report their receipts through an annual infrastructure funding statement instead. Read that statement. It tells you what has been collected for open space in your area and whether any of it has been spent, and an unspent balance is a reasonable question to ask.

Run the levy calculation alongside the obligations rather than after them, using the approach set out in calculating your CIL liability from the charging schedule.

Budgeting at appraisal stage

Model the contribution before the unit mix is fixed, because the mix drives the yield and the yield drives everything else.

As an illustrative example, a scheme of 45 dwellings in a district applying a bedroom-based occupancy table, with a mix weighted towards two and three bedroom houses, generates a higher child yield than the same floorspace delivered as one and two bedroom flats. Swapping ten houses for twenty flats changes the play space obligation materially, and it changes the sales value too. Model both.

Then put the contribution in the appraisal as a cash flow item tied to its trigger, rather than as a lump sum at commencement. A payment due on occupation of the twentieth dwelling behaves very differently from one due on implementation.

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This is general guidance, not legal advice, so check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.