As part of its mission to combat fuel poverty and cut carbon emissions, the UK government launched the Energy Company Obligation scheme—now in its fourth phase, known as ECO4. Running from April 2022 through March 2026 and backed by a £4 billion investment, ECO4 focuses on upgrading the UK’s least energy-efficient homes, particularly those rated EPC band D to G. The initiative prioritises low-income and vulnerable households, aiming to lower energy bills, support green jobs, and help the UK meet its net-zero goals.
What Is ECO4 Trying to Achieve?
ECO4 isn’t just about making homes warmer, it’s a holistic strategy to create healthier, more energy-efficient living spaces for those who need it most. The key goals include:
- Reducing fuel poverty by improving the energy performance of homes and lowering heating bills.
- Cutting carbon emissions, helping the UK stay on track with its environmental commitments.
- Creating jobs in the low-carbon economy, with an estimated 18,000 roles supported across the sector.
Eligibility is primarily based on household income and benefit status, but under the ECO4 Flex pathway, local councils can also nominate residents who are vulnerable but don’t meet standard criteria.
The Whole-House Retrofit Approach and the 'Fabric-First' Model
A major shift under ECO4 is the emphasis on whole-house retrofits. Instead of installing one-off energy measures, this approach looks at the home as a complete system. The idea is to make multiple improvements in one coordinated effort—maximising efficiency, comfort, and value for money.
Central to this strategy is the fabric-first principle. This means prioritising upgrades to the building envelope—such as loft, wall, and floor insulation—before turning to technology like new heating systems. However, sealing up a home to improve insulation also makes ventilation more important than ever. Without proper airflow, you risk trapping moisture and pollutants indoors.
Why Ventilation Matters in Energy-Efficient Homes
When you insulate and airtighten a home, you naturally reduce heat loss—but you also limit natural airflow. That’s where problems like damp, condensation, and mould can creep in, along with a build-up of harmful indoor pollutants.
To address this, ECO4 follows PAS 2035 standards, which require a full property assessment to ensure any energy upgrades include appropriate ventilation measures. Good ventilation is not optional, it’s essential.
That’s where mechanical ventilation comes in.
The Role of dMEV Fans in ECO4 Retrofits
Decentralised Mechanical Extract Ventilation (dMEV) fans are an ideal solution for many homes undergoing ECO4-funded improvements. These fans are specifically designed to provide continuous, low-level extraction in individual rooms—typically kitchens and bathrooms—where moisture and pollutants are most concentrated.
Benefits of dMEV Fans:
- Targeted extraction: dMEV units run continuously at a low trickle speed and increase airflow when needed, removing steam, odours, and pollutants directly from high-moisture areas.
- Energy efficient: Built to comply with SAP Appendix Q and Part F of Building Regulations, these fans use minimal electricity while delivering a consistent flow of clean air.
- Quiet operation: Advanced acoustic design means modern units operate almost silently, contributing to a more comfortable living environment.
- Simple retrofitting: Their compact size and straightforward installation make dMEV fans an easy addition to retrofit projects—fitting right in with the whole-house approach of ECO4.
- Cost-effective: Affordable to purchase and cheap to run, dMEV fans offer excellent value while maintaining indoor air quality.
Why dMVHR Units Also Deserve Attention
While dMEV fans handle extraction, decentralised Mechanical Ventilation with Heat Recovery (dMVHR) systems go a step further. These units not only remove stale air—they also capture the heat from it and use it to warm incoming fresh air. This process significantly reduces heat loss, helping households maintain a comfortable temperature while using less energy for heating.
Though slightly more expensive upfront, dMVHR units are a smart long-term investment, particularly for highly insulated homes where energy loss needs to be minimised without compromising on air quality.
Key Benefits of dMVHR Systems:
- Heat recovery for efficiency: Recycles heat from outgoing air to keep indoor spaces warm with less energy use.
- Dual-purpose ventilation: Combines air extraction with filtered fresh air intake, supporting health and comfort.
- Ideal for airtight homes: Helps maintain air quality without sacrificing the benefits of insulation.
Final Thoughts
While insulation and heating are often in the spotlight when discussing home energy improvements, ventilation is just as crucial, especially under the ECO4 framework. Installing effective mechanical ventilation solutions like dMEV or dMVHR systems ensures that air quality remains high, moisture is managed, and energy savings are protected.
For households benefiting from ECO4 retrofits, these ventilation systems provide a simple, regulation-compliant, and cost-effective way to stay warm, breathe easy, and reduce energy bills. As professionals working closely with government and local authorities, we strongly encourage homeowners and installers to treat ventilation as a vital part of the energy efficiency journey, not an afterthought.
Below are a selection of dMEV and dMVHR units that we recommend for you to explore:
dMEV
dMVHR