Renewable Heat Incentive Statistics: Data From the Closed Scheme

The Renewable Heat Incentive was a government financial incentive to promote the use of renewable heat, intended to help reduce carbon emissions and meet the UK's renewable energy targets¹. It ran in two parts: a Non-Domestic RHI that opened in November 2011, and a Domestic RHI that opened in April 2014 and closed to new applicants at midnight on 31 March 2022. Participants who joined and followed the scheme rules received quarterly payments over seven years for the renewable heat their systems were estimated to produce¹.

The closed domestic scheme leaves a long and unusually complete statistical record. Ofgem's annual reporting puts the final position at 117,203 accredited installations, which have generated around 10,745 GWh of heat since the scheme began². Lifetime payments to domestic participants reached £1,163,514,406 by Scheme Year 11, split across air source heat pumps at £442,272,047 (38.0 per cent), biomass at £358,872,897 (30.8 per cent), ground source heat pumps at £342,592,524 (29.4 per cent) and solar thermal at £19,776,937 (1.7 per cent)³.

For a household today, the RHI matters in three ways. Existing participants are still inside a seven-year tariff lifetime and still bound by its ongoing obligations. Anyone buying a house with an accredited system inherits a transferable but time-limited entitlement. And for everyone else, the RHI record is the longest continuous dataset on who installed renewable heat in British homes, against which later schemes and the wider heat pump installation statistics are measured.

What the Renewable Heat Incentive was and why it existed

The plan to introduce the RHI was first announced on 15 July 2009⁶. It was described at the outset as a new government scheme to promote the uptake of renewable heat⁷, and was set up in 2011 to boost rates of renewable and low-carbon heating in Great Britain⁸. When the domestic arm launched, it was presented as the world's first long-term financial support programme for renewable heat, offering homeowners payments to offset the cost of installing low carbon systems⁹.

The design logic was straightforward. Heat is the hardest part of household energy to decarbonise, and the capital cost of a heat pump or biomass boiler is far higher than that of a replacement gas boiler. Rather than paying a lump sum at installation, the RHI paid a tariff over seven years against the renewable heat a system was expected to produce, so that the running subsidy gradually offset the upfront gap. The Climate Change Committee described the scheme in July 2014 as "very generous" while noting that take-up had not followed¹⁰.

The measured outcome is now settled. Ofgem's Scheme Year 11 reporting records 10.1 TWh of estimated heat generation in domestic properties since 2014³, while the latest annual report gives around 10,745 GWh from 117,203 accredited installations². The two figures cover different reporting cut-offs, which is why they differ; the Scheme Year 10 report recorded 811.4 GWh subsidised in that single year, bringing the total since 2014 to an estimated 8.84 TWh at that point¹¹. Read together, they show a scheme whose annual output flattened as accreditations stopped and early participants exhausted their tariff lifetimes.

The two schemes: domestic and non-domestic RHI

The RHI was never a single scheme. The guidance consultation distinguished a Domestic RHI from a Non-Domestic RHI from the start⁷, and the two had different opening dates, payment periods and statistical series.

The non-domestic scheme was by far the larger in energy terms, at 58.3 TWht of subsidised renewable heat¹⁴, and in cash terms it remained larger even late in life: a July 2024 transaction record shows £79,359,757 paid to Ofgem for non-domestic RHI payments against £9,312,975 for domestic payments in the same week¹⁵.

Uptake by technology was also uneven. In non-domestic settings, for the period between November 2011 and September 2014, there were five applications to the scheme for air source heat pumps across the whole of Great Britain¹⁶. The domestic scheme, by contrast, was dominated by air source heat pumps, which account for 4,829 GWh of lifetime generation (47.7 per cent), ahead of biomass at 3,498 GWh (34.6 per cent), ground source heat pumps at 1,692 GWh (16.7 per cent) and solar thermal at 103 GWh (1.0 per cent), from a total of approximately 10,121.7 GWh³.

The domestic scheme was extended by two years in 2020¹, which is why applications continued into the 2021 to 2022 period rather than stopping earlier.

Installations, heat generated and payments: the headline numbers

Three different official totals circulate for the domestic scheme, and they are not contradictory: they are snapshots at different dates.

The Scheme Year 10 report marked the point at which total payments passed one billion pounds for the first time, at £1.06 billion since the scheme began in 2014¹⁷. The Warm Homes Plan technical annex states that since 2014 the Renewable Heat Incentive has made £1.2bn of payments¹⁹, a rounder figure reflecting a later cut-off.

The fall from almost £113.9 million in Scheme Year 10 to almost £106.2 million in Scheme Year 11, a difference of about £7.7 million on those two figures, reflects the mechanical run-off of a closed scheme: the earliest 2014 cohorts have completed their seven years and left the payment roll, with no new accreditations replacing them. Deployment data shows the same pattern: 3,722 domestic RHI installations were recorded in 2021 Q3²⁰, and zero in 2024 Q3²¹ and 2025 Q1²².

How the tariffs and payments worked

Payments were made every three months for up to seven years, the tariff lifetime, from the application date⁵. Tariff rates were set by the Department for Energy Security and Net Zero, with Ofgem responsible as scheme administrator for publishing the current rates⁵.

What made the domestic RHI distinctive was that most payments were not metered. In most circumstances payments are based on the annual heat demand of the property, which can be found on its EPC⁵. Ofgem's reporting sets out the exceptions: solar thermal payments are based on the MCS certificate, and metered installations are treated separately¹⁷. For metered installations, payments are based on the amount of renewable heat produced, up to the annual heat demand on the EPC or the relevant heat demand limit, whichever is lower²³.

This deemed-payment approach has a direct consequence for anyone reading the statistics: the "heat generated" totals are largely estimated rather than measured output. Ofgem's own language is careful, describing quarterly payments for the low carbon heat systems were estimated to produce¹¹. The point matters when comparing RHI generation figures with metered field trials, a distinction explored further in measured versus modelled home energy performance.

Accreditation also brought obligations that did not end at installation. Participants needed to comply with a number of ongoing obligations during the seven-year accreditation to continue to receive payments²⁴. Metering for performance for heat pumps was introduced from 22 May 2018¹.

Which technologies qualified, and the certification requirements

Four renewable technology types were eligible: biomass only boilers and biomass pellet stoves, air source heat pumps, ground source heat pumps, and flat plate and evacuated tube solar thermal panels²⁵. Ofgem's essential guide phrased the same list as air source heat pumps, ground and water source heat pumps, biomass boilers and stoves, and solar thermal in liquid-filled flat plates or evacuated tubes²⁶. The department's household energy efficiency reporting used the formulation of air-source heat pumps, ground and water-source heat pumps, biomass-only boilers and biomass pellet stoves with integrated boilers, and solar thermal panels²⁷.

Certification was the gatekeeper. Ofgem's rule was explicit:

The eligible renewable technology had to be installed and commissioned by an MCS certified installer who could provide an MCS certificate²⁴. The House of Commons Library notes that the Smart Export Guarantee and the previous Feed-in Tariff and Renewable Heat Incentive schemes all require the product and installer to be certified and to meet MCS standards²⁸. Government guidance on device registration makes the same point for installation contractors²⁹. Separately, for installing renewable technologies including heat pumps there are currently six registered competent person schemes: APHC, BESCA, Certsure, HETAS, NAPIT and OFTEC³⁰.

This is why RHI accreditation counts and MCS installation statistics track each other closely for the years the scheme was open, and why the RHI series says nothing about self-installed or uncertified systems.

How the scheme performed against its targets

The Public Accounts Committee's 2018 assessment is the clearest official verdict. The department had cut back its expectations of how much renewable heat will be produced by the scheme by almost two-thirds, and of the reductions in carbon emissions due to the scheme by almost half⁸. Written evidence to Parliament puts it in comparative terms, describing the RHI as marginally more successful than other interventions, although sale volumes of low carbon heating have remained stubbornly low³¹.

Compliance data supplies a second performance measure, and it is less flattering than the headline totals. Ofgem runs two audit programmes: statistical audits, randomly selected to provide a representative view at a 90 per cent confidence level, and targeted audits aimed at higher-risk cases³.

The drop in statistical site compliance from 85.75 per cent to 69.41 per cent across a single scheme year is the most striking movement in the series. The most common material non-compliance in Scheme Year 11 statistical audits was "evidence not provided" with 30 instances (15.2 per cent), followed by "ineligible metering performance" with 29 instances (14.7 per cent); "evidence not provided" also headed the non-material category with 28 instances (14.2 per cent)³.

Criticisms and design problems

Beyond missed targets, three design criticisms recur in the official record.

• Upfront cost barrier. The Public Accounts Committee found that the RHI simply does not work for households and businesses unable to pay the high upfront costs of renewable and low-carbon heating equipment⁸. A seven-year tariff cannot help a household that cannot finance the installation in the first place.
• Biomass and air quality. Government proposed that biomass combustion installations should no longer be eligible for RHI support if located in urban areas that are on the gas grid, a restriction that would apply to new domestic and non-domestic biomass installations of all sizes and to biomass combined heat and power, but not to biogas, which does not create the same level of particulate and other pollutant emissions as biomass combustion³². The restriction would apply only to new applications, and the consultation also asked whether larger biomass plants subject to planning and tighter emission controls should be included, and whether mandatory maintenance checks for existing and new installations should be introduced³². Separately, requirements were set for biomass used in renewable heat installations to meet a set of sustainability criteria³³.
• Metering rules. Ofgem consulted on changes to the independent report on metering arrangements criteria³⁴, reflecting the difficulty of verifying output under a scheme that mostly did not meter it.

A distributional point also emerges from the data: Registered Social Landlords were one of the groups eligible to apply for the DRHI and account for 21.6 per cent of all scheme accreditations³⁵. More than a fifth of the domestic scheme, in other words, went to social housing providers rather than owner-occupiers.

Closure and what came after

The domestic scheme closed to new applicants, including metering and monitoring service package applications, at midnight on 31 March 2022³⁶. The non-domestic scheme closed in March 2021, though extensions ran to 31 March 2023 in some cases¹³. Both had been signalled well in advance: Scottish Government material in February 2021 recorded that the non-domestic RHI was due to close in March 2021 and the domestic RHI in March 2022³³.

Ofgem's account of the transition recorded over 110,281 accredited installations and £819.3m paid to consumers under the closing scheme¹⁸. The replacement model shifted from ongoing tariff to upfront capital grant, a change with consequences that were anticipated at the time. Scottish heat pump sector deal advisory work noted that support under the Clean Heat Grant would be worth less than under the RHI, making domestic heat pumps a less attractive option than at present³⁷. Current grant uptake is tracked separately in the Boiler Upgrade Scheme statistics.

Selling a home with an accredited system

Accreditation does not automatically die with a sale. A DRHI accreditation may be transferred to the new owner³⁸, but only within tight deadlines.

1. The departing participant must contact Ofgem at least 28 days before the sale goes through³⁶.
2. From the date of sale, new owners have 12 months to notify Ofgem of the change and confirm they wish to continue with the accreditation³⁹.
3. The new owner must apply for accreditation within 12 months from the date of sale³⁸.

Independent guidance sets out the same sequence and lists the paperwork: the original MCS certificate number for the heat pump, the installer commissioning certificate and the Energy Performance Certificate number, with payments then available to the new owner for the rest of the eligibility period⁴⁰.

Where the official statistics live, and how to read them

There are two distinct publication families, and confusing them is the commonest error in citing RHI numbers.

Ofgem scheme reporting. Quarterly and annual Domestic RHI reports present the latest statistics on accreditations on the scheme, payments made and feedback from the customer survey⁴¹; from the 2014-15 annual report onward the annual editions also covered renewable heat generated and carbon dioxide saved⁴², with the 2016-17 report carrying the same broader set⁴³ and the 2017-18 report covering accreditations, payments made and renewable heat generated⁴⁴.

Departmental deployment data. The monthly statistics for the RHI programme present the number of applications and accredited installations on the scheme so far, broken down by technology type, Great Britain region and application status, published by the Department for Energy Security and Net Zero⁴⁵. The Renewable Heat Premium Payments data detailed vouchers issued and redeemed by technology type and GB region⁴⁵. RHPP figures were no longer included in the release from January 2015; from March 2016 the release included quarterly data previously published separately; and quarterly reporting was introduced with effect from July 2022⁴⁵. The last update to that dataset was 18 April 2024⁴⁵. An earlier quarterly publication, running to March 2013, summarised deployment under the Non-Domestic RHI and the RHPP householder voucher schemes⁴⁶. The monthly series carries Official Statistics status⁴⁷.

Two practical cautions. The data for the heat pump deployment statistics that carry RHI rows is as of March 2024, in line with the RHI official statistics²², so RHI columns in more recent releases are frozen rather than updated. And the scheme's legal basis, the Domestic Renewable Heat Incentive Scheme Regulations 2014 as amended²⁶, was repeatedly changed, so definitions are not constant across the series. The general principles are set out in how to read UK energy statistics.

What the RHI record means for household energy independence

The RHI moved a meaningful number of homes off fossil heating: 117,203 accredited installations generating around 10,745 GWh². For those households, a heat pump or biomass boiler removed or reduced dependence on a gas or oil supplier and, in the heat pump case, shifted heating onto electricity that can be partly self-generated. Ofgem's Scheme Year 11 reporting notes that storage heaters accounted for 16.4 per cent of the systems replaced³, indicating that a sizeable share of the scheme served homes that were already off the gas grid.

The dependencies that remained are equally clear from the data. The subsidy itself was a seven-year dependence on a government scheme, administered by Ofgem with rates set by the department⁵, and it ends. Eligibility depended on the MCS certification chain, tying households to certified installers and certified products²⁵. Payments depended on an EPC assessment of the property rather than on what the system actually delivered⁵, so a household's income from the scheme was decoupled from its real performance. And the audit record, with statistical site compliance at 69.41 per cent in Scheme Year 11³, shows that continued payment depended on documentary compliance that a significant minority of participants did not sustain.

For households considering renewable heat now, the RHI's most durable legacy is evidential rather than financial. It produced eleven years of accreditation, payment and generation data on a defined, certified population of installations, which is why it remains a baseline in the wider UK home energy statistics and in comparisons with the closed Feed-in Tariff. The scheme also demonstrated the limit the Public Accounts Committee identified: an ongoing tariff does not reach households that cannot meet the capital cost, and no volume of subsidy per kilowatt hour changes that⁸.