Frequently Asked Questions

The Green Space Index is Fields in Trust's annual barometer of publicly accessible local park and green space provision. When we launched the Green Space Index in 2019 it was the first such measure that had been created to take stock of the quantity of local park provision against the population of Great Britain. In May 2023 we released the fifth version of the Index, updated with the latest data.

• GSI Score: This is our own unique measure showing whether an area meets a minimum level of park and green space provision, where a score of 1 demonstrates a minimum standard of provision.
• Provision of green space (ha.): Total park and green space provision within the given area, reported in hectares.
• Provision of green space per person (sqm): The total green space provision per person within the given area, reported in square metres.
• Population not within ten-minute walking access of a park or green space: The number of people who do not live within ten-minute walking access of a park or green space.
• Green space legally protected with Fields in Trust (ha.): Total park and green space provision that is legally protected with Fields in Trust for current and future generations within the given area, reported in hectares.

Building on our Revaluing Parks and Green Spaces research findings in 2018 we developed the Green Space Index to analyse data and provide evidence-led research about the current situation for parks and green spaces and the implications on society We are calling for policy change to ensure parks and green spaces are revalued, not for what they cost to maintain but for the value they contribute to society. We believe that green spaces are good, do good and need to be protected for good.

We update the Green Space Index annually late May/early June.

The May 2019 release of the Green Space Index was the first time that publicly accessible local parks and green spaces had been mapped and analysed in this way. We have only been able to analyse data on park and green space provision since the production of a GB-wide Greenspace map by Ordnance Survey. Prior to that there was not a comprehensive dataset nor was there a way to track change over time.

Each new release of Ordnance Survey’s Green Space product undergoes several changes includes a number of revisions to improve accuracy of the base data, thus we are not able to draw firm conclusions that the changes represent loss or gain of green space due to development despite seeing some changes in our findings.

In order to give a more up to date and accurate picture we have used population projection data for each annual release, whereas the 2019 release used population data from the 2011 Census.

We know that parks are at crisis point and the lack of funding and statutory protection are compounding the issues facing our parks. We also know that populations in urban areas will grow and this will negatively impact on the quantity of green space available to communities. We will continue to explore the potential impact of population change on green space provision and access. We update our population data each year in line with the latest projections to ensure the Green Space Index keeps track not just with annual changes in green space but also in population.

Data from the Green Space Index is not yet available as open data but you are welcome to use the findings in your own research and reports with credit to Fields in Trust and a link to the Green Space Index web page. If you have used the Index's findings then we would love to hear how it has benefitted your project - please get in touch by emailing info@fieldsintrust.org. The full data for each LSOA is not currently available to download but can be viewed within the interactive online map.

We welcome the input of universities, researchers and others who could help us continue to develop and refine the Green Space Index. We would also love to hear from you if you are interested in a partnership to fund this area of our work. You can also make a donation to support our work more widely.

We have created a WebApp covering the whole of Great Britain. The data you see on each map is displayed as part of Lower Layer Super Output Areas (LSOAs) in England and Wales and Data Zones (DZs) in Scotland. These are geographical hierarchies designed to improve the reporting of small areas statistics.

We have produced a WebApp for the whole of Great Britain. The WebApp covers a large geographic area and includes a lot of data so we have tried to make it easy for you to explore and load in your browser.

To aid load times and provide as smooth a user experience as possible we have had to simplify some of the layers, which toggle based on the zoom extent of the map. A full discussion of the types of boundaries we use is available within the Technical Notes found below.

In the May 2023 release of the Green Space Index we have used the April 2023 release of Open Greenspace data from Ordnance Survey. If you find any inaccuracies whilst browsing the OS Greenspace product, you can report these using the contact form on the OS website, selecting "Map errors and omissions". We use population projection data provided by Geolytix. Further information on this is available in the Technical Notes found below.

The Index is predicated on our Guidance for Outdoor Sport and Play which is well-established and respected across the industry having been first released in the 1930s. Our survey found 75% of local authorities adopt this or an equivalent standard. The Guidance gives benchmark standards for parks, playing fields, equipped play and informal green space per 1,000 people.

Local parks and green spaces which are open to the public for recreational use including parks and gardens, informal recreation spaces, children's playgrounds, formal sports areas such as multi-use games areas (MUGA), tennis courts and playing fields. More detailed discussion on typologies of land included is available within the Technical Notes found below.

Before calculating the Green Space Index we make some changes to the data provided by Ordnance Survey, including removal of typologies which aren't included within the scope of our Index, such as national parks, common land, cemeteries and golf courses, as well as the elimination of any overlaps within the data to prevent any double-counting. Full detail on this is available within the Technical Notes found below.

Ordnance Survey's scope only extends to Great Britain. Northern Ireland is served by a separate mapping agency - Ordnance Survey of Northern Ireland - who have not as yet produced any mapping of publicly accessible parks and green spaces. If such data becomes available in the future then we will look to expand the Green Space Index to include Northern Ireland.

The GSI Score is our unique measure of green space provision. To compile the GSI Score we analyse provision of parks and play per 1,000 people and provision of outdoor sport facilities per 1,000 people against our benchmark guidelines to provide a score where 1 indicates a minimum level of provision is being met. This is just a minimum and of course we would always advocate for a GSI Score higher than 1 to ensure everyone within a community is well served by parks and green spaces.

A ten-minute walking distance is a well-established measure of an acceptable distance for a resident to be from their nearest park or green space. Calculating where and how many people are not served by a park or green space within a ten-minute walk can offer a useful addition to judging provision levels with overall quantity alone not capturing distribution of green space across communities. Determining who's within a ten-minute walking distance from a green space can be difficult. Calculating this distance can be done in multiple ways, resulting in different values. Buffers around green spaces are used by most organisations, including Natural England, to identify people living within a ten-minute walking distance as the crow flies. In 2023 we have introduced a new approach which utilises the road network and calculates walking distance between postcodes and entrance points to green spaces thereby creating a service area for each green space to better reflect a real-life situation. While the second approach is more accurate, the buffer method is also widely used because it accounts for a greater surrounding area of the green space. We employ both methods to guarantee a more complete analysis.

We calculate the results in the Green Space Index using the latest GIS software. We are grateful for the support of Esri UK whose ArcGIS Pro and ArcGIS Online platforms we utilise through their non-profit programme.

Through the Green Space Index we analyse publicly accessible local park and green space provision within Great Britain. The Index follows on from our Revaluing Parks and Green Spaces research released in 2018 and supplements our wider policy work in the parks and green spaces sector. The May 2019 release of the Green Space Index was the first time such a measure had been published to take stock of the quantity of local park provision across Great Britain and the annual updates support our evidence-led approach calling for parks and green spaces to be revalued for the benefits they contribute to society.

The Green Space Index covers Great Britain and analyses publicly accessible local park and green space provision as mapped by Ordnance Survey, with a more detailed discussion below of how their data is used. Not within the scope of the Green Space Index is regional park and green space land, such as national parks and common land, or other aspects of green infrastructure such as canal towpaths and grass verges.

Northern Ireland is not included in the Index because park and green space data is not made available by Ordnance Survey of Northern Ireland. If such data becomes available in the future we will look to expand the Green Space Index to cover the province.

The Green Space Index is compiled using the OS Open Greenspace product, with the 2023 release of the Index using the April 2023 release of OS Open Greenspace.

Within the OS Open Greenspace product we use the site extent polygons in all cases. From the site extent layer we exclude four typologies which are not deemed to be within scope of the Green Space Index. The excluded typologies are: Allotments & Community Growing Spaces; Cemetery; Religious Grounds; and Golf Course.

Typologies which are within our scope and which have been retained for analysis are: Bowling Green; Other Sports Facility; Play Space; Playing Field; Public Park or Garden; and Tennis Court.

We have also removed two areas of land, detailed below, which appear within the dataset but we do not deem to be within scope. We are reliant for the Index on the dataset published by OS and have not performed a nationwide review of the accuracy of this data as it is not within our scope to do so, but do believe these examples to be indicative of errors which may currently exist within the data. These have been fed back to OS, who are accepting feedback on errors within the data as they continue their verification process. We will continue to work with them to support this process where we are able.

Land removed from in-scope typologies as not deemed to be within scope of Green Space Index:

• 9E891041-3B3D-2C71-E053-A03BA40A7146 - Whinlatter Forest Park
• 9E89103E-2B7F-2C71-E053-A03BA40A7146 - Rutland Water

Within the Ordnance Survey Open Greenspace data there are instances of spatial overlap which results in duplication of park and green space areas and has the potential to skew our Green Space Index calculations. These overlaps fall into two categories:

• Overlap where small features have been overlaid on larger features.
  • For example a polygon representing a play area sitting on top of a larger polygon representing a park. This leads to double-counting of the area of the play area. We have run analysis to identify areas of overlap and erase the area of the smaller feature from the larger feature, thus removing double-counting but retaining the mix of typologies that may exist on a space.
• Duplication of entire polygons where two or more identical polygons sit on top of one another.
  • Common examples of this are a polygon representing a tennis court layered on top of or below an identical polygon representing an other sports facility. We have controlled for this by analysing identical polygons and only retaining the first one listed within the dataset.

Therefore we have taken every effort to remove all instances of overlapping and duplication from the data as accurately as possible within our scope. As previously noted we are reliant on the dataset published by OS and will continue to work with them to support their verification process where we are able. We have noted accuracy-related revisions since the first release of the OS Greenspace data and it is for this reason we do not yet feel able to draw comparisons to the findings of the first two releases of the Green Space Index. If you find any inaccuracies whilst browsing the OS Greenspace product you can report these using the contact form on the OS website, selecting "Map errors and omissions". We are also committed to working closely with Ordnance Survey to improve green space data across the UK especially with regards to existing legally protected spaces.

Population projection data
Whilst the majority of the Green Space Index is compiled using the OS Open Greenspace product, some measures are calculated by combining analysis of this with population data.

For the 2023 release of the Green Space Index we have in all instances used data for the projected 2023 population, to provide a more accurate product.

For the population figures for 2023 and beyond, we used data provided by Geolytix, who specialise in data and demographics. The projections for years beyond 2023 are modelled from a household first perspective. They use OS address data and combine data on all large-scale planning developments with Census data on household compositions.

In analysing the impact of projected changes in population of green space per capita, we used the projections data calculated by Geolytix. For projections beyond 2025 they apply change at local authority level in 2016-based ONS projections to give precise projections at local authority and national/regional level.

Geographic and statistical boundaries
WWhen visualising data we have produced a single WebApp for Great Britain. Within the App we use 2021 Lower Layer Super Output Area (LSOA) boundaries for England and Wales and 2011 Data Zone (DZ) boundaries for Scotland. All analysis and calculations to compile the Index and data for display in the WebApp has been carried out using full resolution clipped boundaries. To aid load times and provide as smooth a user experience as possible, however, we have presented the data on the WebApp using generalised boundaries.

The Green Space Index is compiled using National Statistics data © Crown copyright and database rights (2023), NRS data © Crown copyright and database rights (2023), OS data © Crown copyright and database rights (2023) and Royal Mail data © Royal Mail copyright and database rights (2023).