ECO4, HUG2, and GBIS Eligibility: How to Get Free Windows and Insulation
Upgrading your windows is an expensive capital expenditure, but for thousands of UK households, it can be effectively free. The current government landscape is dominated by three main schemes: ECO4, HUG2, and the Great British Insulation Scheme (GBIS).
Grant Stacking Table: Which One applies to You?
| Scheme | Primary Focus | Qualifying EPC | Funding Source | Target Group |
|---|---|---|---|---|
| ECO4 | Whole-House Retrofit | D $\rightarrow$ G | Energy Suppliers | Low-income / Fuel Poor |
| HUG2 | Fabric-First (Insulation) | D $\rightarrow$ G | Gov / Suppliers | Low-income / Vulnerable |
| GBIS | Single Insulation Measure | D $\rightarrow$ G | Gov / Suppliers | Inefficient Homes (EPC D-G) |
The “Whole-House” Logic of ECO4
Unlike previous schemes, ECO4 takes a “whole-house” approach. This means you can’t just apply for “new windows.” You must demonstrate that the windows are part of a broader strategy to lift the property’s energy efficiency.
If your home has an EPC rating of D, E, F, or G, you are the primary target for ECO4. The funding is provided by energy suppliers who are mandated by the government to hit carbon reduction targets. To qualify, you are usually required to be on certain benefits or meet low-income thresholds.
Great British Insulation Scheme (GBIS): The “Quick Win”
If you don’t meet the strict low-income criteria for ECO4, you might still qualify for GBIS. This scheme targets the “efficiency gap”—homes that are inefficient (EPC D-G) but not necessarily “fuel poor.”
GBIS Eligibility Quick-Check:
- EPC Rating: Must be D, E, F, or G.
- Council Tax Band:
- England: Bands A-D.
- Scotland & Wales: Bands A-E.
- Measure: Focuses on single insulation measures (e.g., loft or cavity wall), but this often creates the thermal baseline required to then justify window upgrades through other funding.
HUG2: The “Fabric First” Layer
The Home Upgrade Grant (HUG2) is designed to “top up” ECO4. It provides funding for those who have already had some improvements but still have “cold spots” in their home. It is specifically focused on the “fabric first” approach—insulating the shell of the building before upgrading the heating system.
What most guides miss: The “TrustMark” Gatekeeper
The most common reason grant applications fail isn’t the homeowner’s eligibility—it’s the installer.
To claim funding from ECO4 or GBIS, you must use a TrustMark-registered installer. If you hire a “local handyman” and then try to claim the cost back from the energy company, you will be rejected. The TrustMark registration ensures that the work meets the technical standards required for the government to count the carbon savings.
For those performing a deep retrofit, integrating grant-funded insulation with a high-performance glazing spec (see our Passivhaus windows spec) can practically eliminate your heating bill. If your home is currently Unmortgageable because of severe damp and inefficient glazing, these grants are the fastest way to restore the property’s value and mortgageability without spending your own capital.
Integration with Energy Autonomy
If you are combine grant-funded upgrades with a solar PV installation via IWantSolar, you are effectively moving your home toward a “Net Zero” operational cost. The grants handle the “leaks” (insulation and windows), and the solar handles the “gain.”
Summary: How to apply
- Check your EPC: If you’re C or above, you’re unlikely to qualify for these specific grants.
- Find a TrustMark Installer: Search the TrustMark directory for “Energy Efficiency” specialists.
- Apply for ECO4 first: If you meet the low-income criteria, this is the most comprehensive funding.
- Fall back to GBIS: If you are in an inefficient home but don’t meet the income thresholds.