Regeneration of Pea-Pod-Like Cellulose Acetate Fibers as Aerogel-Derived Boards for Building Thermal Regulation and Carbon Reduction

Cellulose fibers play significant roles in building passive radiative cooling (PRC) and heating (PRH), benefiting from their porous structure and low thermal conductivity. However, the fixed structure and hydrophilic groups limit the regulation of optical and thermal properties. Herein, mechanically assisted solvent extraction strategy is proposed to regenerate cellulose acetate (CA) as pea-pod-like fibers. Different from natural fibers, photonic and thermal-storage particles are introduced into CA fibers to regulate optical selectivity and thermal properties. Further considering of building surface assembly, the biomimetic fibers are compressed into rigid bio-boards to achieve buildings thermal regulation. The results demonstrate that PRC bio-board can reflect ~ 94% of solar radiation and emit ~ 96% of thermal radiation and achieve ~ 11 ℃ (I_solar > 1500 W/m² and T_environment ~ 35 ℃ at daytime) and 6 ℃ (nighttime) of cooling effects. The phase-change PRH bio-board integrates solar absorption (A_solar ~ 96%), thermal insulation (T_shielding ~ 30 ℃) and storage functions, which can heat building ~ 12 ℃ under I_solar ~ 1000 W/m² and slowly releases heat for > 1200 s. According to evaluation, the bio-units can save over 45% of energy, 1.042 $/m² cost and 4.978 kg/(m² year) CO₂ emission in Nanjing annually. It is believed that the results have positive effects on clarifying the structure–effect relationship and promoting the commercialization of thermal management materials.