A network of microfibers are fabricated with a core-shell construction from sustainable materials, where the core includes a phase-change material, such as coconut oil, and the shell includes a biomass, such as cellulose. The microfibers are made via a wet-wet electrospinning process utilizing a coaxial spinneret with an inner conduit and an outer conduit. The biomass and the phase-change material are coaxially extruded into a coagulation bath including a mixture of ethanol and water. The collected microfibers exhibit a beaded structure of PCM aggregates and biomass connecting regions between the aggregates and are effective to aid in the thermoregulation of the immediate environment surrounding the network. The microfibers are suitable for use in a variety of sustainable products such as wearable thermoregulating textiles, wall/ceiling panels, insulation, packaging material, and more.