Innovative hybrid timber-mortar construction system: LCA analysis and comparison with a traditional dry CLT system

In recent decades, timber construction systems have experienced remarkable development in Europe due to their sustainability, thermal performance, in-door comfort, and aesthetic qualities. Various hybrid construction systems have also emerged, combining the properties of wood with other materials to further enhance specific performance aspects. This research investigates a timber-mortar construction system (NIDUS), which combines a lightweight wooden frame (balloon frame) with a lime-based infill (lime, perlite, and hemp) that provides thermal mass and wall continuity. The timber-mortar system is therefore compared with the Cross Laminated Timber (CLT) construction system. The study employs an inte-grated methodological approach combining design activities, digital mod-elling, and mock-up experimentation to compare the energy performance and environmental impact of the two construction systems. The initial phase involves the design of nodes and stratigraphies, along with thermo-hygrometric and energy analyses to assess the building enve-lope’s performance. Four design solutions were analysed: two for the NIDUS and two for the CLT system. Subsequently, 3D digital models were used as references for energy and environmental simulations. In parallel, aspects related to prefabrication, assembly times, construction sequencing, and connection quality were evaluated using two full-scale mock-ups, con-structed by the National Research Council - Institute for Bioeconomy (CNR-IBE) at its laboratories. The results highlight that the timber-mortar system achieves performance comparable to CLT, representing a viable solution. In particular, the sys-tem’s greater thermal mass contributes to improved summer performance, while life-cycle impacts in terms of Global Warming Potential (GWP) are approximately 6% lower, excluding biogenic carbon.