When it comes to improving the energy efficiency of solid wall homes in the UK, insulation is one of the most
impactful upgrades you can make. At Prima Energy Solutions, we help homeowners across Yorkshire choose
the right insulation method under ECO4 and GBIS grants. Two of the most popular options are **Internal Wall
Insulation (IWI)** and **External Wall Insulation (EWI)**—but which one is best for your home?

What Is Internal Wall Insulation?

Internal Wall Insulation involves fitting insulation boards or stud walls on the inside of your property’s external
walls.
**Best for:** Homeowners looking for a cost effective solution that can be installed room by room.
**Pros**- Lower installation cost compared to EWI- Minimal external changes—ideal for conservation areas- Can be installed selectively in cold rooms
**Cons**- Slight reduction in internal room space- Disruption while work is carried out inside- Potential for thermal bridging if not installed properly

What Is External Wall Insulation?

External Wall Insulation involves fixing insulation materials to the exterior walls, then covering them with a
protective render.
**Best for:** Homes needing full house insulation with no loss of indoor space.
**Pros**- No loss of internal living area- Improves external appearance and weather protection- Provides complete thermal coverage with fewer cold spots
**Cons**- Usually more expensive than IWI- Changes the look of the property (not ideal for listed buildings)- May require planning permission in some location

Which Option Should You Choose?

Which Option Should You Choose?
The right insulation method depends on your property type, budget, and renovation goals.

Choose Internal Wall Insulation if… 

 You want a budget friendly option.

 You only need to insulate certain rooms. 

 You live in a conservation area.

 You don’t mind a slight reduction in room size.

 Choose External Wall Insulation if…

 You want maximum energy savings.

 You want a whole house upgrade.

 You want to protect exterior walls from weather. 

 You want to keep all indoor space.

ECO4 & GBIS Grants – Make It Affordable

 Both IWI and EWI can be funded through government schemes like **ECO4** and **GBIS**, helping households
cut costs significantly—sometimes fully covering installation depending on eligibility.

Prima Energy Solutions handles the full process: 

Free survey
Eligibility check
Grant application
Professional installation

 Why Choose Prima Energy Solutions?
We are Yorkshire’s trusted ECO4 installers, helping homeowners reduce energy bills with high quality insulation
and heating upgrades.

Visit us at: www.primaenergysolutions.co.uk
Phone: 0330 133 2004
Email: info@primaenergysolutions.co.uk

Final Thoughts
Both IWI and EWI can dramatically improve warmth, comfort, and energy efficiency. If you’re unsure which suits
your home, our experts can assess your property and guide you toward the most cost effective
option—especially with grant support available