In the pursuit of climate-resilient infrastructure and lowcarbon development, bio-based thermal insulation materials have garnered significant interest as environmentally sustainable alternatives to conventional petroleum-derived insulators such as fiberglass, polystyrene, and polyurethane foam. Among various lignocellulosic resources, oil palm biomass, particularly oil palm trunk (OPT) and empty fruit bunches (EFB), has emerged as a highly promising and underutilised feedstock. These residues are abundantly available in Southeast Asia, especially in Malaysia and Indonesia, which together, account for over 80% of global palm oil production (Nabila et al., 2023).