Bio-based insulation materials in sustainable constructions: A review of environmental, thermal and acoustic insulation, durability, and mechanical performances

Traditional building insulation often relies on synthetic materials such as fiberglass and foam. While effective, these materials pose environmental challenges due to their petrochemical origins and lack of biodegradability. In response, there is growing interest in developing natural alternatives to improve the sustainability of the construction industry. In this perspective, recent research has focused on bio-based materials, both engineered and natural, for use in the construction industry as building insulation. Within this framework, we perform one of the most extensive and comprehensive reviews to date (including a total of 395 studies) on carbon footprint (CF), thermal conductivity (λ), Noise Reduction Coefficient (NRC), durability, and mechanical properties of various bio-based building insulation materials, drawing on available experimental studies. Through this review, we gain a thorough understanding of the performance characteristics and environmental impacts of these materials, allowing us to identify key trends and correlations. Building on this knowledge, we establish practical, yet accurate, predictive equations that correlate λ with mass density (ρ), while NRC results a multi-function of ρ and thickness (t). By establishing predictive equations for thermal and acoustic performance, this work provides a solid foundation for optimizing the use of bio-based materials in sustainable construction practices. The study also highlights the environmental advantages of bio-based materials, including their ability to sequester carbon during growth and their potential for recycling, contributing to a circular economy. Overall, our findings support the transition to environmentally friendly, energy-efficient, and economically viable building practices, providing a solid foundation for the adoption of bio-based insulation materials.