What is ECO4?
The Energy Company Obligation (ECO4) is a four-year UK government scheme running from 27 July 2022 until 31 March 2026. Under ECO4, energy suppliers are obligated to help improve energy efficiency and reduce heating costs in eligible domestic properties.
The scheme targets £224.3 million in annual bill savings by the end of March 2026, focusing on low-income households and properties with poor energy efficiency ratings (EPC bands D-G, particularly F and G).
Important deadline: ECO4 officially ends on 31 March 2026, though the government has consulted on extending it by 6-9 months to provide smoother transition and stronger consumer protections. All obligations must be fully met by the deadline.
What the Government Has Said About ECO4
The government's approach to ECO4 emphasises:
- Whole-house retrofit: ECO4 uses a whole-house approach guided by PAS 2035, looking at multiple retrofit measures together rather than piecemeal upgrades
- Fabric-first principle: Insulation, airtightness, and ventilation must be addressed before or alongside installing heat pumps or other renewable technologies
- Quality assurance: All installers must be TrustMark-registered, and projects must follow PAS 2035/2030 standards with proper evidence and documentation
- Renewable energy inclusion: ECO4 includes heat pumps, solar panels, and connections to district heating systems when they meet scheme requirements
- Minimum requirements: Properties must improve by at least one EPC band (F/G to D, D/E to C)
Recent concerns: A government review found extremely high failure rates for external wall insulation installations under ECO4 since 2022—98% require corrective work. This has led to 38 installers being suspended and proposals for market reforms with new restrictions and oversight to boost accountability.
What ECO4 Means for Installers
For installers working on ECO4 projects, the requirements are comprehensive and mandatory. Understanding these requirements is essential for successful project delivery and compliance.
Mandatory Standards and Accreditation
PAS 2035 / PAS 2030:
- PAS 2035 governs the overall retrofit process: assessment, design, coordination, quality assurance, sequencing, and monitoring
- PAS 2030 governs the actual installation work: workmanship, quality management systems, and measure delivery
- All energy efficiency measures installed under ECO4 must comply with both standards
TrustMark Registration:
- All installers must be TrustMark-registered (or equivalent) to deliver ECO4-funded works
- All projects must be lodged into TrustMark's Data Warehouse, enabling audits (desktop and onsite)
- Non-compliance can lead to voiding of certificates, remediation requirements, and possible sanctions
MCS Certification (for renewable technologies):
- For heat pumps, installers must hold MCS certification under MIS 3005 (design, sizing, installation)
- For solar PV and solar heating, installers must hold MCS certification under MIS 3001
- Recent updates clarify rules for hybrid systems and fabric-first requirements
Specialist Roles Required
PAS 2035 creates distinct roles, each with specific responsibilities. For ECO4 projects, these roles are mandatory:
- Retrofit Assessor: Carries out whole-dwelling assessments (energy performance, fabric condition, ventilation, heat loss modelling, identifying defects). Must be certified and approved by a Retrofit Assessment Scheme
- Retrofit Coordinator: Central role overseeing the project end-to-end. Ensures all assessments are done, designs meet standards, installs follow specifications, manages risk, and ensures post-installation evaluation. Must be appropriately qualified (e.g., Level 5 Diploma in Retrofit Coordination and Risk Management) and registered via TrustMark
- Retrofit Designer: Produces technical retrofit designs (sequence of interventions, ventilation strategy, drawings/specs) based on the whole-house assessment
- Retrofit Installer: Physically installs measures per PAS 2030; for renewable installations, also compliant with relevant MCS standard
- Retrofit Evaluator: Assesses whether intended outcomes (lower energy bills, comfort, carbon savings) have been met
Technical Requirements for Heat Pumps and Solar
Heat Pumps:
- Installed to MCS MIS 3005 standard (design, sizing, installation)
- Fabric-first principle: insulation, airtightness, ventilation must be addressed before (or alongside) installing a heat pump
- Whole-house assessment must show that the house is suitable (heat loss, space for low temperature heating, etc.)
- For hybrid systems: heat pump must provide minimum 55% of calculated heat load at design temperature, with flow temperature of 55°C
Solar Panels:
- MCS certification MIS 3001 applies (Solar Heating / Solar Thermal; PV under separate MIS standard)
- Projects must demonstrate that PV will reduce heating costs (eligibility often requires property heating powered by electricity or heat pump)
Compliance and Quality Assurance
Installers must:
- Lodge all projects (assessments, designs, install reports) into TrustMark's Data Warehouse and Ofgem's systems with sufficient photographic and documentary evidence
- Undergo site visits by Retrofit Coordinator during installation for certain measures (e.g., external/internal wall insulation, underfloor, flat roofs) depending on risk pathway
- Complete post-install testing and commissioning: Heat pumps must be commissioned; flow/return temperatures checked; controls configured. Ventilation, airtightness (where applicable) must meet spec, and test certificates furnished
- Prepare for audits: Desktop and/or onsite inspections by TrustMark / scheme providers
Challenges for Installers
The recent government review highlighting 98% failure rates for external wall insulation under ECO4 demonstrates the importance of:
- Proper assessment: Thorough retrofit assessments that identify risks and inform design decisions
- Quality installation: Following PAS 2030 standards rigorously, with proper oversight and documentation
- Risk management: Understanding property condition, ventilation requirements, and potential issues before installation
- Evidence capture: Comprehensive photographic and documentary evidence throughout the project
What ECO4 Means for Customers
For homeowners and tenants, ECO4 offers significant opportunities to improve energy efficiency and reduce heating costs, but understanding eligibility and requirements is essential.
Eligibility
You may qualify for ECO4 if:
- Your home has a low EPC rating (bands D-G, especially F or G)
- You're on a low income or receive certain benefits
- You're in social housing or the privately rented sector
- Your property is suitable for whole-house retrofit measures
What to Expect
Retrofit Assessment Required:
- You'll need a retrofit assessment under PAS 2035 to determine property condition, suitable measures, and ensure compliance
- The assessment will evaluate: energy performance, fabric condition, ventilation, heat loss, and identify defects
- An EPC will be generated (often via SAP or RdSAP) to establish the starting SAP band
Whole-House Approach:
- ECO4 uses a whole-house approach, looking at multiple retrofit measures together
- Measures might include: insulation (wall, roof, floor), heating upgrades, heat pumps, solar panels, ventilation improvements
- The retrofit must improve your property by at least one EPC band (F/G to D, D/E to C)
Quality Assurance:
- All work must be carried out by TrustMark-registered installers
- Projects must follow PAS 2035/2030 standards
- You should receive proper documentation, commissioning certificates, and evidence of compliance
Benefits for Customers
ECO4 can deliver:
- Lower energy bills: Improved insulation and efficient heating systems reduce running costs
- Better comfort: Warmer homes with better ventilation and temperature control
- Reduced carbon emissions: Lower energy use and renewable technologies support net zero goals
- Property value: Improved EPC ratings can increase property value
- Free or subsidised upgrades: For eligible households, measures may be fully funded
Acting Soon
With ECO4 ending on 31 March 2026 (with possible short extension), timing matters. If you're interested in ECO4-funded upgrades:
- Check your eligibility with your energy supplier or local authority
- Arrange a retrofit assessment to determine what measures are suitable for your property
- Work with TrustMark-registered installers who understand PAS 2035 requirements
- Ensure all work is properly documented and compliant
How Retrofit Assessments and Renewable Surveys Support ECO4
Retrofit assessments and renewable surveys are fundamental to successful ECO4 projects. They provide the evidence, analysis, and documentation needed for compliance, quality assurance, and effective project delivery.
Retrofit Assessments
Retrofit assessments under PAS 2035 are mandatory for ECO4 projects. They provide:
- Whole-house evaluation: Comprehensive assessment of property fabric, insulation status, heating, ventilation systems, and occupancy behaviour
- Energy performance analysis: EPC generation via SAP or RdSAP, establishing the starting SAP band and identifying improvement opportunities
- Risk identification: Identifying defects, ventilation issues, and potential problems that could affect retrofit measures
- Design foundation: Information needed for Retrofit Designer to create technical designs and intervention sequences
- Compliance evidence: Documentation required for TrustMark lodgement and Ofgem reporting
Renewable Surveys
For ECO4 projects involving heat pumps or solar panels, renewable surveys provide:
- Heat loss calculations: Essential for heat pump sizing under MCS MIS 3005, ensuring systems are correctly sized for the property
- Site suitability assessment: Evaluating whether the property is suitable for heat pumps (space, heating system compatibility, ventilation requirements)
- Solar assessments: Roof condition, orientation, shading, and structural suitability for solar PV installations
- Evidence capture: Photographic and documentary evidence of site conditions, measurements, and constraints
- MCS compliance support: Survey documentation that supports MCS certification and grant applications
Integration with ECO4 Process
Retrofit assessments and renewable surveys integrate with the ECO4 process as follows:
- Pre-retrofit assessment: Retrofit Assessor evaluates property condition and energy performance
- Design phase: Retrofit Designer uses assessment data to create technical designs; renewable surveys inform heat pump/solar specifications
- Installation: Retrofit Installer follows approved designs, with Retrofit Coordinator overseeing quality
- Post-installation: Retrofit Evaluator assesses outcomes; evidence is lodged with TrustMark and Ofgem
What Vertex Can Do for ECO4 Projects
Vertex provides retrofit assessments and renewable surveys that support ECO4 projects from start to finish.
Retrofit Assessments
We provide retrofit assessments that meet PAS 2035 requirements:
- Whole-house evaluation: Comprehensive assessment of property fabric, insulation, heating, ventilation, and occupancy
- Energy performance analysis: EPC generation and SAP/RdSAP assessments to establish starting bands and improvement targets
- Risk identification: Identifying defects, ventilation issues, and potential problems
- Evidence-led documentation: Photographic and documentary evidence that supports TrustMark lodgement and compliance
- Installer-ready reports: Structured documentation that Retrofit Designers and Coordinators can use immediately
Renewable Surveys
We provide renewable surveys for ECO4 projects involving heat pumps and solar panels:
- Heat pump surveys: Site assessments, heat loss calculations, and suitability evaluations that support MCS MIS 3005 compliance
- Solar PV surveys: Roof assessments, shading analysis, and structural evaluations for solar installations
- Heat loss calculations: Accurate thermal assessments for heat pump sizing and system design
- Evidence capture: Comprehensive photographic and documentary evidence of site conditions, measurements, and constraints
- MCS compliance support: Survey documentation that supports MCS certification and grant applications
Supporting ECO4 Installers
For installers working on ECO4 projects, we provide:
- Fast turnaround: Survey packs delivered quickly to keep projects moving
- Compliance-ready documentation: Evidence and reports that meet PAS 2035, MCS, and TrustMark requirements
- Reduced callbacks: Comprehensive site assessments that identify issues before installation
- Evidence for lodgement: Documentation that supports TrustMark Data Warehouse and Ofgem reporting
Conclusion
ECO4 represents a significant opportunity for installers and customers to improve energy efficiency and reduce heating costs. With the scheme ending on 31 March 2026 (with possible short extension), understanding requirements and acting soon is essential.
For installers, ECO4 requires comprehensive compliance with PAS 2035/2030, TrustMark registration, MCS certification (for renewable technologies), and proper evidence capture. Retrofit assessments and renewable surveys are fundamental to successful project delivery.
For customers, ECO4 offers free or subsidised upgrades for eligible households, but requires working with TrustMark-registered installers and understanding the whole-house retrofit approach.
Retrofit assessments and renewable surveys provide the evidence, analysis, and documentation needed for ECO4 compliance, quality assurance, and effective project delivery. Whether you're an installer preparing for ECO4 projects or a customer exploring eligibility, professional assessments and surveys are essential for success.