Optimized lime-based renders with Phase Changing Materials (PCMs) for energy-efficient and climate resilient traditional and contemporary structures

Improving building energy efficiency is a top priority for the European Union. Member States take measures to encourage property owners to enhance thermal performance and reduce heating and cooling demands. Conventional thermal insulating materials, such as expanded or extruded polystyrene, remain widely used but present drawbacks, such as thermal bridging, imposition of additional loads on the structures and increased building envelope thickness. Hence, alternative solutions are continuously being sought. This experimental study focuses on developing innovative, smart, cementless renders, enhanced with Phase Changing Materials (PCMs), tailored for traditional and contemporary structures in southern Europe. Following a parametric analysis, a series of PCM-enhanced lime composites were designed and assessed for their thermal and physico-mechanical properties. Accelerated weathering tests were also carried out to investigate the durability of the new end-products against salt crystallization, which is critical for restoration and renovation projects. The addition of PCMs at 5% w/w of the binder and aggregates resulted in the optimum performance, considering the experimentally determined thermal, physico-mechanical and durability properties of the end-products. The results confirm that PCMs indeed have the potential to enhance the thermal efficiency of lime-based composites, while careful mix design may allow for tailored selection of end-products based on specific needs. Future market adoption of PCM-enhanced renders is expected to contribute to lower energy consumption, supporting the EU’s strategic goals for energy-efficient and climate-resilient structures.