Built Up Areas (2022) FAQ

Who created the 2022 version of Built Up Areas?

Ordnance Survey created OS Open Built Up Areas with the first version being published in December 2022 under Open Government Licensing (OGL). The Office for National Statistics and Scottish Government made significant contributions in the design of the dataset to ensure it is fit for purpose and focussed on the needs of the wider public sector.

What is the difference between ‘OS Open Built Up Areas’ and ‘Built Up Areas (2022)’?

Built Up Areas (2022) is the name ONS are using for this product. This is to retain consistency with the naming of previous products like this that have been produced roughly every decade since the 1980s. The geometry and associated GSS codes of the two versions are identical. However, the format of the naming is different with ‘Built Up Areas (2022)’ providing three name columns: BUA22NM, BUA22NMW and BUA22NMG. BUA22NM either contains the English name or the Welsh/Gaelic name where no alternative English name exists. BUA22NMW contains the Welsh name where an alternative English name exists. BUA22NMG contains the Gaelic name where an alternative English name exists. 2022 Built Up Areas also contains a centroid location for each area, provided in British National Grid Eastings and Northings and Latitude and Longitude.

Where can I find more information about Built Up Areas (2022)?

Ordnance Survey’s product information page for OS Open Built Up Areas contains further information and their product support page contains links to PDFs providing an overview and technical specification of the product

Are the 2022 Built Up Areas the same geography as the 2011 Built-Up Areas?

The 2022 Built Up Areas were created using a methodology based on the 2011 version. However, there are some notable improvements and changes that mean the 2022 Built Up Areas should be considered a new geography and not a continuation of the 2011 Built-Up Areas or 2011 Built-Up Area Subdivisions. This means statistics produced for areas with the same name are not directly comparable. Differences include:

Will a ‘merged’ version of 2022 Built Up Areas that joins nearby areas together, like the 2011 Built-Up Areas did, be produced?

Yes. This will be called Built Up Conglomerations.

Why do only some 2022 Built Up Areas have Welsh or Gaelic names?

We have only used the data contained in OS Open Built Up Areas to populate our name fields. If Ordnance Survey do not currently hold a Welsh or Gaelic name in their data used to assign names to areas then we cannot currently include them.

How are Built Up Areas (2022) in Scotland different to NRS Scottish Settlements and Localities?

Built Up Areas in Scotland are not designed to replace NRS Settlements or Localities. The methodologies used to create these products are different so are not comparable. NRS have also published short paper that explains the key differences between the two products and suggestions on which product to use in Scotland in certain circumstances.

How were centroids for Built Up Areas (2022) calculated?

Due to some Built Up Areas having odd shapes, centroid locations calculated in R using the st_centroid and st_point_on_surfance functions in the sf package were deemed inappropriate. This was because centroids either didn’t fall within the area they were meant to represent or because they were placed in locations that could not be considered near the centre of features. As such, a custom method was used. 100,000 random points were generated inside each area. A convex hull was then produced around each area. Whichever of the 100,000 points in an area was furthest away from its convex hull was selected as that areas centroid. For a limited number of areas a further adjustment was done to ensure all centroids would intersect with clipped to the coastline 2022 Local Authority District boundaries.

How have the GSS codes been assigned to Built Up Areas (2022)?

Entity codes beginning E63 (England), W45 (Wales) and K08 (Wales/England cross-border) have been assigned unique instance codes based on each areas centroid location. Codes for each entity have been allocated based on their British National Grid Nothing coordinates from North to South. Entity codes beginning S45 (Scotland) have been assigned in ascending alphabetical order.

Do any Built Up Areas (2022) intersect with the English/Scottish border?

No. If they did they would have also been assigned the K08 entity code.

Does ONS intend to publish their own version of the Built Up Extents and Non Built Up Extents layers available in OS Open Built Up Areas?

OS Open Built Up Areas actually consists of three layers:

The ‘Built Up Areas’ layer is the most similar to previous geographies and is what we consider to the ‘primary’ layer, hence why it has been assigned GSS codes. The other layers do not have separate GSS Codes, instead they have been given ‘Related to GSS Codes’ identifiers in the OS dataset.

We will not be producing our own versions of the ‘Built Up Extents’ and ‘Non Built Up Extents’ layers. However, should you require these layers then they can be downloaded via the OS Data Hub and these can be joined to ONS’ Built Up Area product using the GSS codes.

How are the 2021 Output Area, 2021 Lower Layer Super Output Area and 2021 Middle Layer Super Output Area to Built Up Areas (2022) lookups created?

These lookups are for England and Wales only (as Scotland have not released their updated statistical geographies yet). They have been produced by using the 2021 version of population weighted centroids calculated for Output Areas (OAs), Lower Layer Super Output Areas (LSOAs) and Middle Layer Super Output Areas (MSOAs) and intersecting them with each 2022 Built Up Area. This ‘best-fit’ lookup is consistent with how similar types of lookups are produced and adheres to the GSS Geography Policy. It does however mean the same statistical output aggregated to Built Up Areas (2022) using OAs, LSOAs or MSOAs will generate different totals. As such, we recommend using the smallest area geography possible when using the best-fit lookups provided.