Guidance

Warm Homes: Local Grant and Warm Homes: Social Housing Fund Statistics - methodology and background note

Published 27 August 2026

Applies to England

Introduction

This note explains how the Warm Homes: Local Grant (WH:LG) and Warm Homes: Social Housing Fund (WH:SHF) statistics are compiled, their limitations, and how they should be interpreted. It describes the data sources used, how records are processed and validated, and how published figures may be affected by reporting lags and revisions.

Status and standards

These statistics are produced by DESNZ as Official Statistics in accordance with the Code of Practice for Statistics and DESNZ standards for official statistics.

About the Warm Homes schemes

In January 2026, the government published its Warm Homes Plan to upgrade up to 5 million homes by 2030. WH:LG and WH:SHF are both part of this plan, supporting the installation of energy efficiency upgrades and low-carbon heating measures across England.

Warm Homes: Local Grant scheme

WH:LG provides funding to local authorities to deliver upgrades to eligible low-income households in owner-occupied and private rented homes. It is the successor scheme to the Home Upgrade Grant (HUG). Funding allocations were made to local authorities in early 2025. A total of 74 projects involving 271 Local Authorities — over 97% of eligible Local Authorities in England — were allocated funding.

WH:LG covers owner-occupied and private rented homes meeting the scheme’s eligibility criteria.

Warm Homes: Social Housing Fund scheme

WH:SHF provides funding to deliver upgrades to the social housing stock. It is the successor scheme to the Social Housing Decarbonisation Fund scheme. Grant Recipients (GRs) under WH:SHF are:

• local authorities
• combined authorities
• registered providers of social housing (including housing associations and arms-length management organisations (ALMOs) that are registered providers)
• registered charities that own social housing

WH:SHF is also known as WH:SHF Wave 3. A total of 138 projects were allocated funding.

WH:SHF covers social rented homes, with limited treatment of non-social homes in mixed-tenure blocks under the scheme’s infill rules.

The grant funding for both schemes ends in March 2028 but delivery of WH:SHF goes to March 2030, with the final two years using co-funding only. Further details are available in WH:LG scheme guidance and WH:SHF scheme guidance.

Coverage: what the statistics include

The published statistics cover activity delivered in England under WH:LG and WH:SHF from the start of the schemes to a data cut-off date set for each release, usually the tenth working day of the month, covering data up to the end of the previous month. For example, data up to the end of May 2026 were published on 25 June 2026 using records reported and linked by 12 June 2026. Grant Recipients are required to submit monthly returns by the tenth working day of each month. Activity reported or linked after the cut-off is included in subsequent releases.

What is measured

The two main units measured in the published statistics are:

1. individual measures reported by GRs and lodged on the TrustMark data warehouse
2. individual households in which one or more such measures have been installed

Data sources

The statistics are based on monthly returns submitted by Grant Recipients (GRs) through the Grant Reporting System (GRS) and linked to records of measures lodged on the TrustMark data warehouse. A Grant Recipient is an organisation awarded funding under a Warm Homes scheme and responsible for delivering upgrades and reporting scheme activity.

Under both schemes, GRs identify eligible households, confirm that households, properties and measures meet scheme requirements, and record details of the upgrades delivered. All installed measures must be lodged on the TrustMark data warehouse. TrustMark is the Government Endorsed Quality Scheme, and installers must be TrustMark registered and certified to install the relevant measures. The TrustMark data is a true reflection of what the supply chain has told TrustMark about installations. However, it may not be ultimately what gets accepted into the schemes.

A measure is typically reported through two routes. The retrofit coordinator lodges the measure on the TrustMark data warehouse as evidence that it complies with the PAS 2035 standard, while the GR submits a corresponding return through the GRS. The two records are then linked in the GRS, allowing information from the TrustMark lodgement to be used in statistical processing. Once a GRS return and TrustMark lodgement have been successfully linked, the measure becomes eligible for inclusion in the statistics, subject to the validation checks described below.

The difference between GR returns and TrustMark lodgements

There are three groups of records, which correspond to columns (A), (B) and (C) in Table 1:

• (A) TrustMark lodgements: all measures lodged on the TrustMark data warehouse.
• (B) Linked GR returns: GRS records successfully linked to a TrustMark lodgement.
• (C) Unlinked GR returns: GRS records that have not been linked to a TrustMark lodgement.

Column (D) shows the GRS records that proceed to the validation checks used to produce the official statistics.

TrustMark lodgements

The number of TrustMark lodgements is typically higher than the number of linked GR returns because measures may be lodged on TrustMark before the corresponding GR return has been submitted or linked. TrustMark lodgements are not used directly in the published statistics. They contribute only where they can be linked to a GR return and associated with scheme reporting information. However, they provide an indication of additional installation activity that may not yet be reflected in the published figures.

Linked and unlinked GR returns

Linked GR returns are the main source of the published statistics because they combine TrustMark evidence with scheme reporting information. Unlinked GR returns are included in processing for completeness, but most relate to administration or ancillary activity rather than individual installed measures and are therefore excluded during validation.

What Table 1 shows

Table 1 compares TrustMark lodgements and GRS records for both schemes. It shows that some TrustMark lodgements have not yet been linked to GR returns and therefore do not yet appear in the published headline statistics. For measures, columns B and C sum to column D. For households, they do not, because the same household may have both linked and unlinked records; column D therefore shows the distinct number of households entering validation.

Table 1. TrustMark lodgements and GRS records by scheme, up to the end of July 2026

Scheme	Indicator	(A) Total lodgements on the TM data warehouse (n1)	(B) GRS records linked to TM lodgements	(C) GRS records not linked to TM lodgements (n2)	(D) GRS records that undergo validation
WH:LG	Households upgraded	6,692	5,484	6,677	6,678
	Measures installed	14,660	12,485	6,687	19,172
WH:SHF	Households upgraded	17,502	12,900	2,537	12,927
	Measures installed	35,678	26,492	2,549	29,041

(n1: Irrespective of whether they are linked to a GR return in the GRS.)

(n2: These unlinked records are generally used by GRs to report administration or ancillary activity, rather than individual installed measures. They are included in the processing dataset but are not counted as valid reportable measures unless they can be resolved through subsequent validation.)

Timing and revisions

Some installations may not appear in the published statistics immediately because the associated GR return has not yet been submitted or linked to a TrustMark lodgement by the data cut-off date. Records processed after the cut-off are included in subsequent releases. The most recent month shown in the statistics is therefore likely to be underestimated. However, it is included to provide the most complete estimate available at the time of publication. Published figures are therefore provisional and may be revised in later releases

Processing and validation steps that affect measures and households

GR returns are not automatically included in the published statistics. They undergo a series of processing and validation checks, which may exclude some records and affect the measures, households and other information reported in each release.

Attribution to scheme and GR

Each TrustMark lodgement is matched to a scheme (WH:LG or WH:SHF) and to a GR using the identifiers in the lodgement. Lodgements that cannot be confidently matched are not published until the matching is resolved.

Checking completeness of the data

Certain fields must be populated for a measure to be included in the statistics, including:

• installation date
• measure type
• Unique Property Reference Number (UPRN)

From the August 2026 statistics onwards, where a linked GRS record is incomplete, information from the corresponding TrustMark lodgement may be used to complete the record where possible. For example, a TrustMark installation date may be used to allocate a measure to the correct reporting period.

Records are excluded only where the missing or invalid information cannot be resolved, or where the measure type is not recognised under the scheme. This includes administration and ancillary activity that is not associated with an individual installed measure.

The exclusion reasons are shown in Table 2. Where a measure is affected by more than one issue, it is assigned to the first applicable category to avoid double-counting. Records excluded at publication are retained and may be included in a later release if the issue is resolved.

Table 2 shows the number of measures affected by each processing and validation check for both schemes, for the reporting period up to the end of July 2026.

Table 2. Processing and validation outcomes for GRS records, August 2026 statistics

	WH:LG measures (% of total measures)	WH:SHF measures (% of total measures)
Total measures reported by Grant Recipients in GRS	19,172	29,041
Installation date missing (n1)	0 (0%)	0 (0%)
Record not pertaining to an eligible measure (e.g. ancillary or administrative records) (n2)	6,712 (35%)	2,654 (9%)
Property identifier (UPRN) missing	0 (0%)	0 (0%)
Duplicate record (n3)	1,185 (6%)	616 (2%)
Outside scheme delivery window or reporting month (n4)	28 (<1%)	2 (<1%)

(n1: For the July 2026 statistics, records with missing installation dates were excluded. From August 2026 onwards, valid installation dates from linked TrustMark lodgements may be used where available. The number/percentages here are after TrustMark data has been incorporated)

(n2: In the August 2026 statistics, 99% of these records related to ancillary or administrative activity rather than individual installed measures. The remainder were non-eligible measure types present in TrustMark data, such as Smart Airbrick, Hot Water System and Compensation (Pre-existing Heating Controls))

(n3: Duplicate records share the same UPRN, measure type and scheme.)

(n4: The scheme delivery window begins in April 2025. Statistics are published one month in arrears.)

Further information

Household and measure counting rules

A household is counted once per release, regardless of how many measures it has received. A measure is only counted once, regardless of how many components make up its installation (for example, a solar PV measure is only counted once, even thought it might consist of several individual solar panels).

Where a household receives measures in more than one reporting period, it is counted in the period in which the first measure was installed and in cumulative totals thereafter.

Suppression and disclosure control

Small-area or GR-level breakdowns that could disclose information about identifiable households are suppressed in line with DESNZ statistical disclosure control practices. This does not affect overall totals but may limit the availability of some breakdowns.

Average installation costs

Average installation costs are calculated using measure-level cost information reported by GRs in the GRS. They are based only on valid measures with usable cost data and therefore do not cover all measures installed under the schemes.

Average costs based on fewer than five measures are suppressed to avoid unstable or potentially disclosive estimates.

Data linkage to supplementary sources

The statistics are linked to supplementary datasets to provide additional analysis. For example, postcodes are linked to the Office for National Statistics National Statistics Postcode Lookup (NSPL) to assign properties to English regions.

How the two schemes compare for reporting purposes

Both schemes are reported on a consistent basis, using the same data sources, processing rules and validation checks.

Differences between the published statistics reflect differences in the schemes rather than the reporting methodology. The schemes cover different housing sectors, which affects the characteristics of participating households and delivery patterns.

Revisions policy

Figures are provisional and may be revised in later releases as additional information becomes available. Revisions are expected to be mainly upward in early releases because activity is often reported after the initial cut-off date. Each release replaces previously published figures for the periods covered.

The department’s statistical revisions policy applies to these statistics. Users should refer to the latest publication for the current best estimate.

Accessibility

These statistics are published in accordance with the Public Sector Bodies (Websites and Mobile Applications) (No. 2) Accessibility Regulations 2018.

Contact and feedback

Comments and feedback on these statistics can be sent to: EnergyEfficiency.Stats@energysecurity.gov.uk.