GLA population projection service

Created a month ago, updated a month ago

The GLA Demography Team offers a bespoke population projection service to London local authorities. Boroughs can request population projections based on their own choice of assumptions about future housing delivery. These assumptions are submitted to the team via a standard template. The resulting projections are referred to as the Borough Preferred Option (or BPO) and are commonly used to help support local planning and service delivery.

The GLA does not make the BPO projections and submitted housing trajectories publicly available or share them with anyone other than the commissioning borough. Boroughs wishing to publish BPO projections themselves are free to do so.

This service is offered as an optional, free of charge service to London authorities, and is intended to provide users with an alternative to the standard projections that the GLA publishes on the London Datastore.

Access to outputs

The BPO projections are shared with users via private pages on the London Datastore. These pages include all outputs produced under the service since 2019.

To access outputs, users must have a current Datastore account linked to their local government email address and contact the Demography Team to request permissions be granted for the individual pages relating to their local authority.

Notes on completing the development data template

What periods do the year labels in the template refer to?

The year labels in the template nominally refer to periods ending in the middle of that year (i.e. `2025` refers to the 12 month period ending June 30th 2025). However, development data is often readily available only for financial years and it is common to submit data on this basis, with financial year 2024/25 aligning with `2025` in the template.

Development trajectory

The cells in the template represent annual net changes in the number of dwellings.

The current template covers the period 2012-2041 and are pre-populated with estimated annual net dwelling changes for the period 2012-2019, based on modelling of data from the London Development Database.

For the 2022-based and subsequent projections, dwelling stock estimates are anchored to the results of the 2021 Census and it is not essential to include data for dwelling stock changes that occured prior to this point (i.e. up to and including '2021').

Past development data from 2022 up to the base year of the projections, affects the projected population in all future years as dwelling stock in the base year is used in the estimation of relationships between housing and population in the model.

We are not yet able to pre-populate templates with estimated dwelling changes for years after 2019. In future rounds of projections we intend to incorporate data from the Planning Data Hub.

Blank cells are treated as missing rather than no change, and data based on the 2017 Strategic Housing Land Availability Assessment (SHLAA) will be substituted in its place. To indicate no net change in dwellings in a ward in a particular year, users must explicitly enter a zero in the relevant cell.

Self-contained and Non-self-contained development

Self-contained development should be used for standard residential development (e.g. new build/conversion).

Non-self-contained development should be used for development such as student accommodation. This should be added to the template as the equivalent of self-contained units (i.e. a ratio of non-self-contained to self-contained should be applied). The London Plan ratios are:

· 2.5:1 for student housing

· 1:1 for housing for older people (C2)

· 1.8:1 for all other non-self-contained housing

Requesting projections based on multiple different housing scenarios

While we are willing to try and accommodate requests for multiple sets of projections, capacity in the team is limited and there is no guarantee that we will be able to do so in a timely manner.

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