Comparison Guide · Updated June 2026

ECO4 vs Boiler Upgrade Scheme 2026: Green Home Grant Comparison

ECO4 provides free insulation and heating improvements for lower-income households with EPC D or below — fully funded by energy suppliers, no cost to you. The Boiler Upgrade Scheme (BUS) offers a £7,500 voucher toward an air source or ground source heat pump — open to all homeowners regardless of income. The Great British Insulation Scheme (GBIS) sits between these, providing single-measure insulation grants for homes with EPC D or below. This guide compares eligibility, what each scheme funds, typical savings and how to apply.

Last updated: 21 June 2026How we verify

Green Home Grants at a Glance

Scheme	Who qualifies	What it funds	Amount
ECO4	Benefits + EPC D or below	Insulation, heating, heat pumps	Fully free
Boiler Upgrade Scheme	All homeowners	Air/ground source heat pumps, biomass	£7,500 voucher
GBIS	EPC D or below + council tax A-D	Single insulation measure	Fully free

ECO4: Free Energy Efficiency for Eligible Households

ECO4 (Energy Company Obligation 4) is an Ofgem-regulated obligation on the six largest energy suppliers to fund energy improvements in the least energy-efficient homes occupied by low-income households. The obligation runs from April 2022 to March 2026 and is succeeded by the Warm Homes Plan.

Eligibility requires two things:

Benefits criterion: Someone in the household must receive a qualifying means-tested benefit — Universal Credit, Pension Credit, Child/Working Tax Credit, Income-based JSA/ESA, or Income Support.
Property criterion: The home must have an EPC rating of D, E, F or G (EPC A, B or C homes are generally excluded as already energy-efficient).

ECO4 can fund: cavity wall insulation, solid wall insulation, loft insulation, underfloor insulation, heat pump installation, first-time central heating, electric storage heaters, and in some cases solar panels. The entire cost is covered — there is nothing to pay for eligible households.

Boiler Upgrade Scheme (BUS): £7,500 for Heat Pumps

The Boiler Upgrade Scheme provides a capital grant that any owner-occupier in England or Wales can use toward the cost of a qualifying low-carbon heating system. No income means-test applies — the scheme is available to all homeowners.

Grant values from April 2024:

Air source heat pump: £7,500
Ground source heat pump (and water source): £7,500
Biomass boiler: £5,000 (restricted to rural areas off the gas grid)

The average air source heat pump installation costs £10,000-£18,000. With the £7,500 BUS voucher, the out-of-pocket cost is £2,500-£10,500. Larger properties requiring a more powerful unit may cost more.

Great British Insulation Scheme (GBIS)

GBIS sits alongside ECO4 and targets a broader group — any owner-occupier with an EPC D or below, not solely benefit recipients. The GBIS eligibility also includes a council tax banding condition (properties in council tax bands A-D in lower-deprivation areas, or any band in higher-deprivation areas). GBIS funds a single primary insulation measure per home, unlike ECO4 which can fund multiple measures. Check eligibility at the Simple Energy Advice website.

Typical Savings from Each Scheme

Cavity wall insulation (ECO4/GBIS): Typical saving £150-£300/year. One-off treatment, minimal maintenance. Payback: instant (fully funded).
Loft insulation to 270mm (ECO4/GBIS): Typical saving £150-£200/year. Can DIY for homes already partially insulated.
Air source heat pump replacing gas boiler (BUS): Saving varies: +/- £200/year (heat pumps cost more to run than gas at current prices but are more efficient; savings increase significantly if replacing oil/LPG).
Air source heat pump replacing oil heating (BUS): Saving £800-£1,500+/year depending on oil usage and electricity rate.

The combination of ECO4/GBIS insulation measures plus BUS heat pump is the gold standard for energy efficiency improvement — insulating first makes the heat pump more efficient and reduces running costs.

How to Apply for Each Scheme

ECO4: Check eligibility at simpleenergyadvice.org.uk. Contact your energy supplier or an ECO4-registered installer. They survey your property and arrange installation at no cost.
BUS: Get quotes from MCS-certified heat pump installers. The installer applies for the BUS voucher before starting work. You pay the net cost (installation price minus £7,500).
GBIS: Same as ECO4 — check eligibility online, then contact your supplier or a GBIS-registered installer. Available via simpleenergyadvice.org.uk.

Warning: be cautious of cold-callers claiming to offer free grants — ECO4 and GBIS are genuine government-backed schemes but they have attracted some fraudulent installers. Always verify that an installer is Trustmark registered (for ECO4/GBIS) or MCS certified (for BUS).

Frequently Asked Questions

What is ECO4 and who qualifies?

ECO4 (Energy Company Obligation 4) is an Ofgem-regulated scheme running from April 2022 to March 2026, requiring energy suppliers to fund home energy improvements for eligible households. Eligible households must meet two criteria: a means-tested benefits criteria (receiving certain benefits such as Universal Credit, Pension Credit, Child Tax Credit, JSA, ESA, or Income Support), AND a property condition criterion (typically EPC rating D or below). Owner-occupiers and private tenants (with landlord permission) can apply. ECO4 is being succeeded by ECO5/Warm Homes Plan from 2026.

What does ECO4 actually fund?

ECO4 funds a range of energy efficiency measures depending on property need: cavity wall insulation, solid wall insulation (internal or external), loft insulation, underfloor insulation, heat pump installation, electric storage heaters, solar panels (in some cases), first-time central heating installation (for homes without any central heating). Measures are assessed and recommended by the installer. There is no cost to the eligible household — all measures are fully funded.

What is the Boiler Upgrade Scheme (BUS) and how much is the voucher?

The Boiler Upgrade Scheme (BUS) provides a one-off capital grant to homeowners who install an air source heat pump, ground source heat pump or biomass boiler (where appropriate). The grant value from April 2024 is £7,500 for air source heat pumps, £7,500 for ground source heat pumps, and £5,000 for biomass boilers (in rural areas with no access to gas grid). The BUS is open to all owner-occupiers in England and Wales — there is no income means-test.

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Can I get ECO4 and the Boiler Upgrade Scheme?

Technically yes — a household could receive ECO4 funding for insulation measures and also use the BUS for a heat pump, but there are restrictions on combining public funding. Where ECO4 is funding the full cost of a heat pump, the BUS cannot also apply to the same installation. However, ECO4-funded insulation plus a separately BUS-funded heat pump could potentially be combined, but this must be confirmed with both the ECO4 installer and the BUS-registered installer.

What is the Great British Insulation Scheme (GBIS)?

The Great British Insulation Scheme (GBIS) runs alongside ECO4 and targets homes with an EPC rating of D or below. Unlike ECO4, GBIS has a broader eligibility including owner-occupiers who are not necessarily on means-tested benefits but live in a home with a D or below EPC rating and meet a council tax band condition (typically A-D for less deprived areas). GBIS typically funds a single insulation measure per household (cavity wall, loft or solid wall insulation). It is separate from ECO4 and the BUS.

How do I apply for ECO4?

You do not apply directly to ECO4 — you apply through an energy supplier or an approved ECO4 installer. Steps: (1) Check eligibility using an online eligibility checker (e.g. Simple Energy Advice at simpleenergyadvice.org.uk); (2) Contact your energy supplier or an approved installer who will assess your home; (3) The installer arranges the survey and, if your home qualifies, schedules installation — at no cost to you. ECO4 installers must be Trustmark or PAS 2035/2030 certified.

How do I apply for the Boiler Upgrade Scheme?

The BUS application is made by the installer, not the homeowner. Process: (1) Get quotes from MCS (Microgeneration Certification Scheme) certified heat pump installers; (2) The installer applies for a BUS voucher on your behalf before starting work; (3) A voucher is issued (valid for 3 months, can be extended); (4) The installer deducts the voucher value from your bill; (5) The installer redeems the voucher from Ofgem. You must check the installer is MCS certified and BUS-registered, and your property must have an EPC completed before the application.

What are the typical savings from a heat pump installed under BUS?

Savings depend heavily on what you are replacing, your home's insulation standard, and energy prices. Replacing a gas boiler with an air source heat pump in a well-insulated home: annual savings of £100-£400 are typical at current energy prices. Replacing oil heating or LPG with a heat pump: savings of £800-£1,500+ per year are possible given the higher cost of those fuels. Heat pumps are more efficient when the home is well-insulated — the combination of insulation (possibly via ECO4/GBIS) and a heat pump (via BUS) can significantly improve both comfort and running costs.

Is the £7,500 BUS voucher taxable?

No. The BUS voucher is a government capital grant applied to the cost of installation. It is not income and is not subject to income tax. It reduces the capital cost of the installation. If the property is rented out commercially, you would normally claim capital allowances on the installation — the BUS grant reduces the cost basis for capital allowance purposes.

What happens to ECO4 after March 2026?

ECO4 runs until March 2026 under its current framework. The government announced the Warm Homes Plan as a successor — a £6.6 billion programme of home insulation and heat pump grants planned to run from 2025 to 2029. The Warm Homes Plan includes both a Warm Homes: Local Grant (for low-income households, targeted at social housing and private rented sector) and a Warm Homes: Social Housing Fund. The BUS is expected to continue beyond ECO4, though with possible modifications to voucher values.

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About the author

Emma Clarke

UK Tax Writer

Emma Clarke has been writing about UK personal tax since 2018, with a particular focus on Self Assessment, PAYE coding and the practical mechanics of how HMRC actually applies the rules to ordinary salaries. Her work concentrates on translating the dense language of HMRC manuals and Finance Act schedules into worked examples that show, pound by pound, how income tax and National Insurance reduce a gross salary to the figure that lands in a UK bank account. Emma covers the full PAYE lifecycle: tax codes (1257L, BR, K codes, emergency codes), the Marriage Allowance, the High Income Child Benefit Charge, salary sacrifice arrangements and their effect on pensionable pay, the Apprenticeship Levy, and the differences between the rUK and Scottish income-tax regimes. She is particularly interested in the edge cases that catch PAYE employees out — the £100,000 personal-allowance taper, the 60% effective marginal rate it creates, and the interaction between student-loan plans and pension contributions. Every figure in Emma's articles is verified against the current HMRC rates pages and worked through a Self Assessment calculation by hand before publication. She writes to CalcHub's editorial standards: primary-source citations, plain English, no promotional language, and clear "this is general information, not financial advice" disclaimers where appropriate.

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UK tax specialism — PAYE, Self Assessment, National Insurance
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Disclaimer: ECO4 runs to March 2026 and is being succeeded by the Warm Homes Plan. BUS voucher values and eligibility are subject to change. Savings estimates are illustrative and depend on your property and energy usage. Always check current eligibility and grant values at gov.uk and simpleenergyadvice.org.uk before applying.