Evaluating the durability and cyclic thermal performance of lime mortars with microencapsulated PCMs for sustainable energy solutions
Phase change materials (PCMs) have emerged as promising additives for lime renders aimed at moderating indoor temperatures and reducing heating and cooling demand in retrofit applications, including Built Heritage. However, existing studies largely report durability as a macroscopic pass-fail outcom...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2026 |
| País: | España |
| Institución: | Universidad de Navarra |
| Repositorio: | Dadun. Depósito Académico Digital de la Universidad de Navarra |
| Idioma: | inglés |
| OAI Identifier: | oai:dnet:dadun_______::6d01de58464dcacc6f97d99190b2cf75 |
| Acceso en línea: | https://hdl.handle.net/10171/124510 |
| Access Level: | acceso abierto |
| Palabra clave: | Phase Change Materials (PCMs) Lime mortar Durability Cyclability Thermal efficiency |
| Sumario: | Phase change materials (PCMs) have emerged as promising additives for lime renders aimed at moderating indoor temperatures and reducing heating and cooling demand in retrofit applications, including Built Heritage. However, existing studies largely report durability as a macroscopic pass-fail outcome and emphasise initial thermal benefits, with limited evidence on whether thermal functionality is retained after severe environmental ageing. This study addresses this gap by combining durability assessment with an integrated evaluation of postexposure changes in microstructure, mechanical performance, and, critically, the conservation of thermal behaviour and thermal cyclability. Fourteen lime render formulations incorporating microencapsulated paraffin PCMs with melting temperatures of 18 and 24 °C at 5, 10 and 20 % by weight of lime, with and without 20 % metakaolin, were investigated. Specimens were subjected to natural weathering, freeze-thaw cycling and salt attack, followed by post-durability characterisation. Functional thermal stability after ageing was assessed through a thermal agreement metric that directly links durability exposure with the preservation of functional thermal behaviour, enabling evaluation of whether thermal performance is merely present initially or effectively retained over time. In parallel, the retention and cyclic stability of latent heat storage and release were evaluated at both material and laboratory envelope scales. Formulations without metakaolin failed prematurely under freeze-thaw and salt attack, whereas PCM-metakaolin mortars withstood the full ageing programme with limited damage, a refined pore network, and preserved or improved mechanical performance (up to 460%). Importantly, these optimised mortars maintained thermal behaviour closely matching that of the intact reference (generally exceeding 90% and reaching 100% thermal agreement in several formulations) and exhibited stable heat storage and release under repeated cycling. Overall, the results demonstrate that, when appropriately formulated, PCM-lime renders can combine durability with persistent and cyclable thermal performance, supporting their feasibility as longlasting solutions for energy-efficient rehabilitation. |
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