ECO4 vs GBIS: What's the Difference and Why It Matters

Introduction

If you've received a cold call offering "free government insulation," you've likely been targeted by contractors working under either ECO4 or the Great British Insulation Scheme (GBIS). While both are government-funded programs aimed at improving home energy efficiency, they have crucial differences—and both share alarmingly high failure rates.

What is ECO4?

ECO4 (Energy Company Obligation 4) is the fourth iteration of a scheme requiring energy companies to fund energy efficiency improvements in eligible homes.

ECO4 Key Features

• Duration: April 2022 to March 2026
• Budget: £4 billion over 4 years
• Focus: Low-income and vulnerable households
• Measures: External wall insulation, internal wall insulation, cavity wall insulation, loft insulation, underfloor insulation
• Funding: Paid for by energy companies (passed on to all customers via bills)

ECO4 Eligibility

You may qualify for ECO4 if you receive:

• Universal Credit
• Pension Credit
• Income-based JSA or ESA
• Child Tax Credit
• Working Tax Credit
• Or have an annual household income under £31,000

What is GBIS?

The Great British Insulation Scheme (previously ECO+) launched in September 2023 as a broader initiative to retrofit millions of homes.

GBIS Key Features

• Duration: September 2023 to March 2026
• Budget: £1 billion
• Focus: Wider eligibility—includes Council Tax Bands A-D
• Measures: Primarily loft and cavity wall insulation (not external wall)
• Funding: Also funded via energy company levies

GBIS Eligibility

Broader than ECO4—you may qualify if:

• Your property is in Council Tax Bands A-D (England) or A-E (Scotland/Wales)
• You receive any of the ECO4 qualifying benefits
• Your home has an EPC rating of D-G

Side-by-Side Comparison

The Problem: Both Schemes Share the Same Flaws

Despite their differences, ECO4 and GBIS suffer from identical systemic issues:

1. Rushed Installations

Installers are paid per job, not for quality. The NAO found contractors completing external wall insulation in as little as 2 days—work that should take 2-3 weeks.

2. Minimal Oversight

Trustmark inspects fewer than 5% of installations. Both schemes rely on self-certification by the very contractors doing the work.

3. Profit-Driven Targeting

Energy companies subcontract installation work to brokers, who subcontract to installers, who sometimes subcontract again. Each layer takes a cut, leaving minimal budget for quality materials and workmanship.

4. Vulnerable Homeowners

Both schemes specifically target low-income households—the people least equipped to afford remediation when installations fail.

Why ECO4 External Wall Insulation Has a 98% Failure Rate

The NAO report focused heavily on ECO4's external wall insulation (EWI) failures:

• Complexity underestimated: EWI requires specialist skills rarely found in general builders
• Unsuitable properties: Installed on homes with existing damp issues or poor foundations
• Cheap materials: Render systems costing £30/m² used instead of £60-80/m² systems
• Weather conditions ignored: Installations continuing in rain, frost, extreme heat
• No proper surveys: Pre-installation assessments skipped to save time and cost

GBIS Problems

While GBIS avoids the catastrophic EWI failures (by not offering EWI), it still has issues:

Cavity Wall Injection Problems

• Installed in properties with cavity widths below minimum standards
• Used in exposed locations where cavity walls should remain clear
• Incomplete fills leaving cold spots
• Water penetration through poor-quality injection points

Loft Insulation Issues

• Ventilation blocked leading to condensation in roof spaces
• Insufficient depth (250mm minimum rarely achieved)
• Electrical junction boxes buried (fire hazard)
• Insulation installed over damaged roofing felt

Which Scheme Is "Better"?

Neither. Both schemes prioritize speed and volume over quality. The key difference is that GBIS uses simpler measures less likely to cause catastrophic failure.

Red Flags for Both Schemes

Regardless of which scheme, watch for these warning signs:

• High-pressure sales tactics: "Offer ends today" or "Limited availability"
• No survey: Legitimate installers always survey first
• Vague company details: Can't provide company registration number or Trustmark ID
• Upfront payments: Government schemes are free—you shouldn't pay anything
• Rushed timeline: Starting work within days of initial contact
• Subcontractors on site: Company that sold you the work not doing the installation

What You Should Do

Before Installation

1. Verify the company is Trustmark registered (search the official Trustmark website)
2. Get at least 3 quotes—even for "free" work
3. Request an independent survey from a RICS surveyor
4. Ask for references from recent customers (within the last 6 months)
5. Check Companies House for how long the company has existed
6. Insist on seeing material specifications and manufacturer guarantees

After Installation

1. Get an independent completion survey within 30 days
2. Document everything with photos
3. Keep all paperwork including certificates and guarantees
4. Report any issues to Trustmark immediately
5. Monitor for warning signs: damp, condensation, cracking

Future of the Schemes

Following the NAO report, both schemes face uncertain futures:

• ECO4 external wall insulation: Effectively paused pending review
• GBIS: Continues but with enhanced inspection requirements
• New oversight: Trustmark under pressure to reform or be replaced
• Industry consolidation: Many small installers exiting the market

Get Expert Advice

If you're considering work under either ECO4 or GBIS, or if you've already had work completed and are concerned about quality, get independent advice before proceeding or before problems escalate.

Related Articles

• Complete Guide to ECO4 Scheme Problems
• External Wall Insulation Issues & Solutions
• NAO Report 2024: Complete Breakdown