Development of a sustainable and low-carbon thermal insulation material: performance optimization and exergy-based life cycle assessment

Improving the thermal and environmental performance of building envelopes requires insulation materials that are lightweight, moisture-resistant, and sustainable. In this study, a multifunctional composite insulation material was developed using expanded perlite, waste goose down fibers, and a water-based polymer binder, and its thermal, acoustic, and exergetic performances were evaluated. The novelty of the study lies in engineering the perlite–polymer interface to simultaneously control heat and moisture transfer. Surface modification using a water-based resin and hydrophobic treatment formed a thin polymer film on perlite particles, significantly reducing capillary transport and decreasing water absorption from 88 to 6% without compromising pore continuity or insulation performance. The composite composition was optimized using Response Surface Methodology (Box–Behnken Design). The optimized material exhibited a thermal conductivity of 0.052 W/m·K and a density of approximately 200 kg/m3, providing a lightweight structure and reducing structural load compared with cement-based perlite materials. Acoustic measurements showed sound absorption coefficients exceeding 0.9 at high frequencies, indicating effective thermo-acoustic insulation performance. An exergetic life cycle assessment revealed optimum insulation thicknesses ranging from 0.039 to 0.090 m depending on climatic conditions, with total environmental impact values between 580 and 1360 mPts/m2 year and CO2 emission reductions of 72–85%. The use of a water-based polymer binder together with the valorization of biological waste may provide a lower environmental impact than conventional cement-based systems, although a complete life cycle assessment of the binder itself was beyond the scope of this study. The results demonstrate that interface-engineered, lightweight bio-based composite insulation materials can significantly reduce heat transfer, exergy losses, and environmental impact in building applications.