Development of Novel Cellulose-Based Aerogel Composites for Thermal Insulation in Nigerian Building Envelopes: Synthesis, Characterisation, and Performance Modelling

Thermal insulation of building envelopes is a critical energy efficiency strategy in Nigeria's hot tropical climate, yet conventional insulation materials are predominantly imported petroleum-based products with limited environmental sustainability. This research develops novel cellulose-based aerogel composite insulation materials from locally sourced agricultural cellulose, establishing a complete synthesis-characterisation-performance modelling framework for building envelope application in North West Nigerian climatic conditions. Cellulose aerogels were synthesised from rice straw cellulose from Kebbi State by dissolution in ionic liquid, gelation, and supercritical carbon dioxide drying. Composites were formed by incorporation of silica aerogel particles and polyvinyl alcohol cross-linking to improve mechanical robustness. Thermal conductivity, specific heat capacity, density, mechanical compressive resistance, and moisture sorption were comprehensively characterised. A coupled heat and moisture transfer simulation model was developed and calibrated against experimental data, then applied to model annual thermal performance of aerogel-insulated wall assemblies in the Sokoto climate zone. Life cycle environmental impact assessment compared the aerogel composite with conventional expanded polystyrene and glass wool insulation. Results demonstrate thermal conductivity of 0.021 W/m.K for optimised composite aerogels, significantly below both expanded polystyrene and glass wool comparators. Building energy simulation predicted 28 percent annual cooling energy savings for aerogel-insulated buildings relative to uninsulated construction in Sokoto climate. Compressive resistance exceeded minimum structural requirements for wall cavity insulation installation. Life cycle assessment indicated 62 percent lower global warming potential than expanded polystyrene on a per-unit-R-value basis, confirming superior environmental profile. The research establishes a complete scientific basis for cellulose aerogel composite commercialisation as a sustainable building insulation material domestically produced from Nigerian agricultural residues. Keywords: cellulose aerogel, thermal insulation, building envelope, rice straw, life cycle assessment