Thermohygro-Acoustic Performance and Lifecycle Implications of Plant- and Animal-Based Biocomposite Insulation Systems for Sustainable Buildings

Abstract

Background: The drive to reduce embodied carbon in the built environment has refocused attention on bio-based insulation materials derived from plant and animal agricultural residues and by-products. These materials—ranging from hemp and bagasse to sheep wool, poultry feather blends, and puffed rice composites—offer potential advantages in thermal resistance, hygrothermal buffering, acoustic absorption, lightweight construction, and circularity. However, their in-use performance is multifaceted and sensitive to manufacturing, binder chemistry, moisture history, ageing, and fire/flotation properties. Comprehensive assessment that integrates thermophysical characterization, hygrothermal ageing behavior, acoustic performance, mechanical compatibility with structural substrates, and lifecycle implications is required to credibly position these materials for mainstream adoption.

Objectives: This study synthesizes the contemporary literature to construct a cohesive, theory-rich analysis of bio-based insulation systems, interrogating mechanisms of thermal and acoustic insulation in plant- and animal-fibre aggregates, the influence of binders and cementitious matrices, hygrothermal ageing processes and their effects on composite performance, and the broader consequences for lifecycle carbon and regulatory compliance. The objective is not merely to summarize findings but to theorize material–environment interactions, show where empirical evidence converges or diverges, and recommend rigorous research protocols for future validation.

Methods: The approach combines critical synthesis and theoretical elaboration rooted in published experimental characterizations, finite element and micromechanical interpretations, and lifecycle assessment frameworks. Evidence is drawn from thermal and acoustic measurement studies, hygroscopic aging experiments, bond and fatigue behavior of composites in hygrothermal environments, and LCAs of hemp concrete and lime binders. Emphasis is placed on mechanistic explanations (pore architecture, fibre–matrix interfaces, capillary condensation, and sorption hysteresis) and on reconciling disparate measurement techniques (steady-state vs transient methods).

Results: Patterns emerge showing that aggregate geometry and porosity dominate thermal conductivity, while fibres with hollow or corrugated structure provide enhanced thermal resistance and acoustic absorption (Sáez-Pérez et al., 2020; Liao et al., 2022). Binders (lime, magnesium oxychloride, geopolymeric routes) critically influence moisture buffering, mechanical cohesion, and CO₂-related benefits (Forster et al., 2019; Zorica et al., 2022). Hygrothermal ageing reduces interfacial adhesion in composite systems and can increase thermal conductivity through moisture-driven heat transport and microstructural collapse (Wang et al., 2019; Liu et al., 2020; Al-Lami et al., 2020). Life cycle analysis indicates net benefits for hemp and similar bio-aggregates when production pathways minimize transport and energy-intensive processing (Prétot et al., 2014; Viel et al., 2018).

Conclusions: Bio-based insulation systems present a compelling pathway toward lower-carbon building envelopes, provided material selection, binder chemistry, moisture management, and fire safety are rigorously engineered. Future research should prioritize standardized hygrothermal ageing protocols, multi-scale modelling linking microstructure to thermal-acoustic performance, and integrated LCA coupled with durability modeling to quantify long-term carbon and service-life tradeoffs. Policy frameworks should evolve to recognize hygrothermal buffering, biogenic carbon storage, and repairability as legitimate credits in building performance standards.