Post-war flats in London blocks, built 1950-1982

Latest lodged RdSAP/SAP certificate per London address where property type is Flat or Maisonette and the construction age band is '1950-1966', '1967-1975', '1976-1982' or a single year from 1950 to 1982, and where the GLA stock-model unit holds 6 or more addresses. The address count is a proxy for a purpose-built block: the register does not record whether a flat is purpose-built.

1. 37.4% of the 290,788 certified post-war flats in multi-address blocks are rated D or worse, the lowest share of the five domestic studies. 59.9% are band C.
2. 63.8% have cavity walls, and 29.7% of all these certificates (46.6% of the cavity-walled) record an unfilled cavity. Cavity wall insulation is the most frequent recommendation, on 38.8% of certificates (most common cost text '£500 - £1,500').
3. 19.7% are lodged as system-built, a construction type the register's standard wall measures fit less well.
4. 46.2% of these flats were lodged as social rented and 28.3% as privately rented (shares of those with a known tenure). 28,090 privately rented flats (39.4%) fall below the 2030 band C standard (confirmed policy, not yet law).
5. Only 72.5% of the below-C flats show a potential rating of C or better, the lowest of the five domestic studies.

Consents

Flats have no householder permitted development rights, so external changes that materially alter appearance (external wall insulation, different windows) generally need planning permission. That applies more strictly in the 13.2% of these flats that sit in conservation areas, and the 1.5% that are listed need listed building consent. Cavity fill and roof insulation are whole-block measures that usually need the freeholder or landlord to act, not the individual leaseholder. Wall measures for system-built blocks need specialist survey.

Sequencing

1. Establish who can act. Cavity fill and roof insulation are whole-block measures that usually need the freeholder or landlord, not the individual leaseholder.
2. Survey the walls: confirm which cavities are unfilled, and commission a specialist survey for the 19.7% lodged as system-built.
3. Programme planning applications for anything that changes the outside, such as external wall insulation or windows of a different appearance; listed building consent for the 1.5% that are listed.
4. In-flat measures such as lighting, heating controls and boiler replacement can go flat by flat while the block-level work is agreed.

Planning statements are general context for England, not legal advice. Article 4 directions vary by borough and were not checked for these figures.

• MHCLG Energy Performance of Buildings register, domestic certificates and recommendations, lodgements to 2026-09-09 (non-address fields OGL v3)
• GLA London Building Stock Model units and UPRN membership (address count per unit), OGL v3, imported 2026-09-12
• GLA London Datastore Conservation Areas, OGL v3, 2026-09-12
• Historic England NHLE listed-building polygons, OGL v3, 2026-09-12

Data month September 2026.

Building units (GLA London Building Stock Model): Contains public sector information licensed under the Open Government Licence v3.0 (Greater London Authority / UCL Bartlett Energy Institute and CASA). Contains OS data (c) Crown copyright and database right, published under the Ordnance Survey presumption to publish.

Energy performance certificates (MHCLG register): Energy Performance of Buildings Data England and Wales (c) Crown copyright.

Listed buildings (Historic England): © Historic England 2026. Contains Ordnance Survey data © Crown copyright and database right 2026. The Historic England GIS Data contained in this material was obtained on 12 September 2026. The most publicly available up to date Historic England GIS Data can be obtained from HistoricEngland.org.uk. Licensed under the Open Government Licence v.3.0.

Conservation areas (GLA London Datastore): Contains public sector information licensed under the Open Government Licence v3.0.

Every rating here is certified: the most recently lodged energy performance certificate for each address. Modelled ratings, the GLA’s 2017 estimates for buildings without a certificate, are never averaged in; where a population relies on them they are counted separately. Figures come from read-only queries run on 22 and 23 October 2026. Counts that could identify a building are merged or left out, and no addresses or owner names are published.

• The register's age bands are 1900-1929 and 1930-1949, so a 'pre-1919' archetype and a '1945-1980' archetype could not be isolated. Studies use pre-1930 and 1950-1982 instead, and the 1930-1949 semi study includes wartime and early post-war builds.
• Domestic archetype membership uses facts lodged on each address's latest certificate (property type, built form, age band), so domestic archetype counts are certified addresses by construction and unit-level certified coverage cannot be computed for them. Unit-level coverage is given for heritage-defined populations (conservation-area and listed domestic units) and for non-domestic units.
• 'Purpose-built', 'converted' and 'mansion block' are not recorded in the register or the stock model. The post-war flats and pre-1930 flats studies use the number of addresses in the GLA stock-model unit (2-5 vs 6 or more, from 2023 AddressBase UPRNs) as a proxy and label it as one.
• Certified means a lodged register certificate (RdSAP/SAP or CEPC). GLA 2017 aggregate rows and modelled (rvEPC) ratings are excluded from every distribution. Modelled ratings appear only as separate counts of units that rely on them.
• The unit of analysis for ratings is the address (UPRN): its most recently lodged certificate, with ties broken as the product does (lodged date, then record order). A stock-model 'unit' can be a whole block, so unit counts and address counts differ. 29.5% of London's latest domestic certificates are past 10 years from lodgement and may predate works since done.
• Numeric domestic recommendation codes are labelled with the register's own summary text, taken from certificates BuildGrade holds with both code and text. This assumes a code means the same across register versions. Code 7's current register text reads '50 mm internal or external wall insulation', and older certificates phrase it differently. Hot-water-cylinder codes 2 and 3 were left out of the top-measure lists.
• Recommendation rows are loaded for 79-97% of the latest domestic certificates and 97-99% of the latest non-domestic certificates, depending on lodgement year (some certificates carry no recommendations), so recommendation shares are lower bounds.
• Cost text is reported exactly as lodged and varies with register version (PV, for example, carries '£3,500 - £5,500', '£5,000 - £8,000' and '£9,000 - £14,000'), so the most common text and its share of rows is given. The texts are not current prices. Lighting cost text varies per certificate (most common share under 15%). Non-domestic recommendations carry a payback category (SHORT, MEDIUM, LONG, OTHER), not a £ cost.
• Heritage flags are spatial matches applied to the whole stock-model unit: listed means the centroid is within 5 m of an NHLE polygon or the footprint overlaps one by at least half; conservation area means the centroid is inside a GLA polygon. Every flat in a flagged block inherits the flag, so listed counts can be over or under. Listed matches: 10,294 domestic units by centroid and 5,551 by footprint.
• Tenure is as recorded at lodgement and may have changed since. Certificates with unknown or blank tenure are excluded from tenure shares (tenure-known share given per study). The MEES counts are screening counts, not compliance findings, and exemptions are not modelled.
• MEES status. Domestic: the E floor is law for private lets (since April 2020); band C by 2030 is confirmed policy, not yet law (government response 21 January 2026; needs legislation, and compliance is to be judged on reformed EPC metrics). Non-domestic: the E floor is law (since April 2023); the 2027 C milestone is not being taken forward, and B by 2030 was revised on 18 June 2026 to B from 2031 for buildings over 1,000 m², where cost-effective, which is not yet law. These are BuildGrade's recorded policy positions; check the current government position before relying on them.
• Wall descriptions marked 'as built ... (assumed)' are RdSAP defaults where the assessor could not verify the construction (for example 79.4% of 1930-1949 semis lodged as solid brick). Treat them as lodged descriptions, not survey findings.
• The potential rating on a certificate assumes every recommended measure is installed, including measures that may need planning permission or listed building consent, so 'potential C or better' is an upper bound on what is consentable.
• Consent statements (permitted development, conservation-area cladding, listed building consent, flats lacking householder rights) are general planning context for England, not legal advice, and are not computed from the database. Article 4 directions vary by borough and were not queried.
• London only: units outside the 33 London local authorities were not used. Other UK cities are in preparation; the Bristol and Cardiff pilots are not yet live.

All six studies: method and caveats