Bio-based materials for the energy-efficient retrofitting of buildings

Historic buildings are a fundamental part of the cultural, social and architectural identity of Italy and Europe. They include structures built in different eras, often predating the introduction of modern energy and seismic regulations, characterised by traditional construction techniques and the use of locally sourced natural materials. From an energy perspective, these buildings generally perform below current standards, with high heating and cooling requirements and limited capacity to control thermal and humidity flows. In recent decades, growing attention to environmental sustainability has led to a rethinking of strategies for intervening in existing buildings. This poses a complex problem: on the one hand, the need to improve the energy performance of buildings; on the other, the obligation to preserve their historical, artistic and material values. In this context, the traditional approach based on the use of industrial materials and standardised solutions is often inadequate or incompatible. Invasive or irreversible interventions can, in fact, alter the physical and hygrometric balance of historic structures, leading to degradation such as interstitial condensation, mould and deterioration of the original materials. Interest in the use of bio-based materials and natural techniques is therefore part of a broader theoretical debate concerning the relationship between conservation, sustainability and technological innovation. Thanks to their natural origin, their compatibility with traditional building techniques and their strong environmental performance, these materials represent a potential synthesis between conservation requirements and energy efficiency objectives.