The case for ECO and against boom and bust funding cycles: A case study of solid wall insulation

Project: External Wall Insulation (EWI) Retrofit of a 1930s Semi-Detached Home

Location: Shepperton, Surrey

Partners: Pioneer Insulation (Installer) & Cotality (Retrofit Coordination)

Funding: ECO4 Flex Grant + customer contribution; ECO4 Flex Route 3 – NHS Referrals

The Challenge: living in a "fridge"

Like many UK homes built in the interwar period, Sian and Pete’s 1930s detached property was constructed with clinker blocks - a material known for poor thermal performance. Despite some more recent extensions and double glazing, the house remained difficult to heat.

Key Issues Identified by Residents:

• Thermal Performance: Sian and Pete described their home as a "fridge," with gas bills nearing £2,000 annually.‍
• Damp & Mould: Black mould grew behind furniture on external walls and inside wardrobes, damaging clothes and creating a persistent damp smell, meaning wardrobe doors were having to be left open.‍
• Health Impact: One resident suffered from asthma, waking up wheezy due to the cold, damp air.‍
• Acoustics: Proximity to Heathrow and a busy road meant noise pollution was a constant disturbance.

"It was a very difficult property to manage. Once we put a Christmas tree against the wall and when we took it down, to my horror, there was just a load of black mould. We had to be careful putting anything against an exterior wall." – Sian, Resident

The Solution: A Whole-House Approach

The residents secured funding through the ECO4 Flex grant (specifically the NHS referral for health/severe asthma condition) after researching options online. They chose Pioneer Insulation, a family-run business recommended to them by word of mouth for prioritizing quality over price, to deliver the project.

The retrofit measures:

The Retrofit Measures:

• External Wall Insulation (EWI): Installation of a Rockwool (mineral wool) system, chosen for its superior fire safety and acoustic properties and better environmental impact compared to polystyrene.
• Ventilation Strategy: Installation of trickle vents and door undercuts to ensure adequate airflow and prevent condensation in the newly airtight envelope.  Existing extract and purge ventilation was already compliant.
• Aesthetic Upgrade: Removal of dated mock-Tudor beams and application of a clean, off-white silicone render with matching black plinths and rainwater goods.

The role of Cotality

While Pioneer delivered the installation, Cotality provided the essential Retrofit Coordination. This involved:

1. Independent Scrutiny: Acting as a "second pair of eyes" to validate the technical quality of the work.
2. Compliance & Data: Managing the complex documentation required for TrustMark and grant funding.
3. Peace of Mind: Ensuring the retrofit plan was safe, appropriate for the building, and executed to the highest standard.

"Being scrutinised by Cotality helps us sleep at night when it comes to compliance requirements ... knowing that we've done a good job and there's a team of experts out there that have looked at and signed off our work." – Camelia Tartza, Pioneer Insulation

The Process: best practice in retrofit

Successful retrofit requires more than just sticking insulation to a wall. Pioneer’s approach illustrates best practice for the sector:

1. Detailed assessment

Before work began, a thorough survey was conducted to identify existing issues, such as roof overhangs and potential leaks. This is in addition to a retrofit assessment that considers the whole home’s energy performance and condition, such as damp and mould risk. Pioneer employs a 69-step pre-installation checklist to ensure the property is technically ready to receive insulation.

2. Managing the "performance gap"

Pioneer Insulation frequently delivers work where a homeowner contribution is essential in order to reach the required standards at a high level of quality.  The focus on quality is essential to the company’s sustainability, to attract paying homeowners and avoid reliance on the peaks and troughs of government funding. In addition to concerns about the sector’s race-to-the bottom on price, Pioneer Insulation owners Andrei and Camelia identified additional drivers of low quality across the industry:

• Subcontracting: Due to uncertain funding, solid wall insulation is often delivered by larger contractors who pass the jobs down to subcontractors, sometimes involving multiple layers of subcontracting. This means less accountability and more room for miscommunication and confusion. To avoid this, Pioneer Insulation manages and oversees projects  from the first customer contact through installation and handover, with all key parts of the job completed by full-time employees and the company owners involved in every single job. It means they can deliver consistent quality installations by highly trained teams who take pride in their work.
• Oversight: Larger installers have decided to employ their own Retrofit Coordinators, however Pioneer report the independence of Cotality’s retrofit coordination as a benefit – a fresh pair of eyes, deep technical knowledge, and advice they say is “priceless” as no house is the same and no job is straightforward.
• Weather Management: Government funding tends to be announced in April, procured through the summer, with delivery required by the following Spring. This means delivering through the coldest, wettest months.

It is obviously more difficult to do this work in winter. We spend half the time fighting the weather and doing our best to stay warm and keep morale high. And then we get to the best time of year to install, and there’s no funding available.  Andrei Tartza, Pioneer Insulation

3. Resident engagement

Speaking to Sian and Pete it is clear that good communication was vital. They were briefed on the timeframe, the space required, and the work required inside the house such as the necessity of ventilation changes (like trickle vents) to maintain a healthy indoor environment post-insulation.

The Results: "Money very much well spent"

Sian and Pete report that the impact of the retrofit was immediate and transformative.

1. Thermal comfort & energy savings

The heating requirement dropped dramatically. The heating now runs for just two hours in the evening, retaining warmth throughout the night (staying around 18°C until morning).

2. Health & wellbeing

The resident with asthma reported a significant reduction in symptoms, no longer waking up coughing or wheezing. The damp smell has vanished, and wardrobe doors can finally be kept closed without fear of mould.

3. Acoustic insulation

An unexpected but highly valued benefit was the soundproofing achieved by using the more Premium Rockwool insulation slabs, as opposed to the chemical-based materials used across the industry. The EWI system has blocked out street noise and significantly dampened the sound of overhead aircraft.

4. Aesthetics

The property has been modernized, increasing its kerb appeal and garnering praise from neighbours.

"It’s money very much well spent... Lower energy bills and I’m less wheezy than I was in the mornings... And the silence is amazing, I’m sleeping really well." – Sian, Resident

Lessons for the Sector

This project highlights critical lessons for scaling up UK retrofit:

1. Quality Over Quantity: The "race to the bottom" on pricing often leads to poor installations (e.g., bridging damp proof courses, cutting pipes and wires). This project proves that a quality-first approach, supported by resident contributions where possible, delivers lasting results.
2. The Importance of Independent Coordination: Independent oversight by retrofit coordinators like Cotality protects both the homeowner and the installer, ensuring compliance and building trust.
3. Grant Awareness: The residents only found the ECO4 Flex grant by chance, and found Pioneer by word of mouth. Better signposting of funding options is essential via public sector portals (e.g. central and local government, and health services) or one stop shops like Ecofurb who blend grants with homeowner’s contributions.
4. Whole-House Thinking: Treating insulation, ventilation, and heating as a connected system is the only way to prevent unintended consequences like mould.

Ready to transform your home?

Whether you are a homeowner or landlord looking to reduce bills or a local authority seeking reliable retrofit partners, quality coordination and an attention to detail is the key to success.