A new technical report under the Clean Energy for EU Islands initiative explores practical insulation solutions for traditional stone-walled buildings, focusing on the specific challenges faced on Cape Clear Island, Ireland.
Stone buildings are a defining feature of many European islands, contributing to local heritage and identity. However, their solid construction, lack of insulation and exposure to harsh coastal conditions often result in poor energy performance and high heat losses.
The report highlights that improving energy efficiency in such buildings is not a straightforward upgrade. Instead, it requires a balanced approach that respects architectural heritage while addressing thermal performance and moisture behaviour. A key message is the need for “breathable” and compatible materials to ensure that walls retain their ability to absorb and release moisture, avoiding long-term damage.
To support decision-making, the study provides a structured framework that helps stakeholders assess whether external or internal insulation solutions are most appropriate, depending on constraints such as heritage protection, wall condition and environmental exposure.
The report also outlines a range of insulation options. External solutions—such as breathable render systems, insulation boards with lime-based finishes, and ventilated cladding—generally offer the most robust performance, particularly in exposed island environments. Internal solutions, including insulating plasters and board systems, can be effective where façade preservation limits external interventions but require careful design to manage moisture risks.
Importantly, the study underscores that retrofit success depends not only on the choice of materials but also on the quality of design and installation. Particular attention must be paid to junctions, ventilation and moisture management to prevent issues such as condensation, mould growth and thermal bridging.
Overall, the findings demonstrate that with a context-specific, moisture-aware approach, insulation retrofits can significantly improve comfort and reduce energy demand, while preserving the durability and character of traditional stone buildings on Europe’s islands.
You can read the report here Insulation Solutions for Stone Wall Buildings – Cape Clear Island | Clean energy for EU islands