A University " thesis " is studying how lime mortars can store heat to improve the energy efficiency of buildings

Andrea Rubio Aguinaga (Barañáin, age 28), who holds a bachelor’s degree in Chemistry and a Ph.D. in Chemistry from the University of Navarra, completed her thesis on lime mortars capable of storing and releasing heat to help regulate the temperature inside buildings. The research was supervised by Dr. José Ignacio Álvarez Galindo and Dr. Íñigo Navarro Blasco.

The idea stems from Europe’s architectural heritage, which includes traditional buildings that—having been constructed in an era when energy efficiency was not a priority—fall far short of current energy performance standards. Therefore, the “ challenge ” initiative aims to reduce these buildings’ energy consumption and environmental impact without losing sight of their heritage value and the materials used in their construction.

To achieve the mortars’ “ development ,” Rubio has incorporated phase-change materials (PCMs), substances capable of absorbing heat when the temperature rises and releasing it when the temperature drops again. Testing prototypes exposed to real-world weather conditions has allowed him to verify the material’s performance in a potential real-world “ status .”

In turn, throughout the “ thesis ” project, Rubio has worked with different types of PCM, quantities, and activation ranges. “We’ve also studied their environmental impact and cost because often a solution can yield excellent results in the ‘ laboratory ’ and yet be difficult to implement in practice due to its price, its impact, or application challenges,” he explains.

"The ultimate goal of the ' research ' ( goal ) would be to move toward renovations that are not only more energy-efficient, but also compatible, durable, and viable from both an environmental and economic standpoint," he adds.

The next step for Dr. Rubio will be to subject these materials to real-world conditions and monitor their performance over longer periods. “This would allow us to better understand how to adapt these coatings to each building and how to make the most of their ability to improve thermal performance,” she says. And, in this way, “we can provide clear guidelines to help architects and renovation professionals decide how and where to use them.” In other words, from the “ laboratory ” to the actual building—and from the actual building to a solution that can be routinely incorporated into heritage renovation projects.
 

References
· Rubio-Aguinaga, A.; Kyriakou, L.; Fernández, J.M.; Navarro-Blasco, I.; Álvarez, J.I.; (2026) Multi-PCM Lime Mortars Incorporating Polymer-Shell and Form-Stable Phase Change Materials for Energy-Efficient Building Envelopes. Polymers 18 (12), 1481. DOI: 10.3390/polym18121481.

· Rubio-Aguinaga, A.; Kyriakou, L.; Fernández, J.M.; Navarro-Blasco, I.; Pavía, S.; Álvarez, J.I.; (2025) Sustainability of PCM-lime mortars for heritage retrofitting: Carbon footprint and impact on energy demand across climates. Case Studies in Construction Materials 23, e05294. DOI: 10.1016/j.cscm.2025.e05294.