Development of PLA/Pulp Biocomposites for Daytime Radiative Cooling in Building Exteriors

As the energy demand for indoor temperature regulation continues to rise, passive radiative cooling has emerged as a promising technology for building exteriors. This study investigates the daytime radiative cooling capabilities of biocomposites composed of polylactic acid (PLA) and manufactured pulp powder. The cooling performance of the material is governed by a dual mechanism: the engineered structural morphology of the composites enables significant broad-band solar reflectance, while the intrinsic chemical properties and functional groups of the components facilitate efficient mid-infrared thermal emission. Experimental testing of the optimized formulation, containing a high pulp fraction of 70 wt%, demonstrated a net cooling power of 110.17 W/m² and achieved a surface temperature reduction of 11.1 °C below ambient conditions. Furthermore, biodegradability assessments confirmed that the composite undergoes complete decomposition within 18 days. These combined thermal and environmental metrics suggest that the proposed biocomposites are highly suitable for scalable and sustainable exterior building cooling, offering a practical alternative to conventional active cooling systems.