The Mayor of London The London Assembly

Housing supply data sources

Last update: September 2023

This note sets out the two measures of housing supply used by the GLA, reflecting the different targets set out in the Mayor’s London Plan and London Housing Strategy.

London Plan

The housing provision targets set out in the London Plan are defined in terms of total net housing supply, comprising three components:

  • Conventional completions: self-contained homes from new build, conversions or changes of use
  • Non-conventional completions: non-self-contained housing such as bedrooms in hostels or halls of residence
  • Change in long-term empty homes (those empty for more than six months), where a decrease is an addition to supply and an increase is a subtraction.

Progress against these targets is monitored in the London Plan Annual Monitoring Report. The most recent Annual Monitoring Report was published in November 2022, covering the financial year 2019/20, but from Spring 2023 according to the new AMR framework.

The source for conventional and non-conventional completions is the Planning London Datahub, which incorporates data from its predecessor the London Development Database. The Datahub is a detailed database of housing developments created from data provided by London borough planning departments and checked by the GLA. The number of long-term empty homes is monitored using annual statistics reported by the Department for Levelling Up, Housing and Communities (DLUHC), based on local authority Council Tax data.

In 2020/21, the latest year for which data on all components is available, the Datahub reports that total net housing supply in London was 32,613, comprising 30,593 conventional completions, 4,290 non-conventional completions and an increase of 2,270 in the number of long-term empty homes.

The conventional component of total housing supply is reported by the GLA to DLUHC who publish it as part of their national statistics on the ‘Net supply of housing’. In the latest figures published in November 2022, they report a total of 37,204 net conventional completions in London in 2021/22.

DLUHC also publish quarterly ‘indicators of new supply‘ based on building control data. These statistics are not comparable to the conventional housing supply statistics published by GLA or DLUHC themselves, as they cover only new build developments and are reported on a gross rather than net basis. They are also known to undercount even new build completions.

A more useful indicator of new housing supply are the statistics on Energy Performance Certificates for new dwellings published by DLUHC. These track new supply as measured by the London Development Database quite closely (see part 3.3 of Housing in London 2019 for a comparison), but do not give a tenure breakdown.

London Housing Strategy

The affordable housing targets set out in the London Housing Strategy are monitored using DLUHC’s national statistics on affordable housing supply. These statistics cover not just new build but also acquisitions of existing private sector homes for affordable housing. They are released on an annual basis with a lag of several months, and combine data from a range of sources including GLA programme monitoring statistics.

GLA funding supports the majority of affordable housing supply in London, and publishes its own statistics on these homes on a quarterly basis, with a shorter time lag than DLUHC. The most recent GLA statistics show that in 2022/23 there were 25,658 affordable homes started in London with GLA support, and 13,954 completed.

DLUHC’s statistics, taking into account homes funded from other sources, show that there were 19,977 affordable homes started and 12,071 completed in London in 2021/22. DLUHC figures for 2022/23 are not yet available.