This study introduces a novel gypsum-to-gypsum concept that enables the seamless integration of thermal storage functionality into gypsum boards using cold-bonded gypsum aggregates (CBAs) as PCM carriers. Herein, the PCM selected, technical-grade paraffin, exhibited a melting point of similar to 28 degrees C, suitable for semi-arid building envelope applications. A reproducible water-controlled granulation method was developed to address the rapid setting behavior of gypsum, comparing intermittent water spraying and continuous linear feeding. The latter demonstrated superior granulation performance, achieving similar to 95 % yield with over 40 wt% of granules within the target 4-8 mm size range. Optimal granule formation occurred at water-to-binder ratios between 19.8 and 22.2 %. Sodium bicarbonate foaming was found to increase total porosity (46.5 to 52.1 %) and decrease loose density (821 to 699 kg/m(3)), but simultaneously reduced accessible porosity (35.4 to 28.8 %), thereby limiting PCM impregnation. Non-foamed CBAs achieved the highest PCM uptake (28.4 wt%) following vacuum impregnation at 120 degrees C for 30 min, yielding form-stable composites with a latent heat capacity of 71.4 J/g. Gypsum boards incorporating 40 vol% CBAs met the EN 13279-1 standard, identifying this substitution level as optimal. This formulation also showed improved acoustic performance, with a peak sound absorption coefficient of 0.6 at 1 kHz. Field testing conducted in a rooftop test cell under semi-arid climate conditions showed that PCM-enhanced boards reduced indoor surface temperatures by up to 10 degrees C and delayed peak heat transfer. Post-exposure DSC confirmed the PCM retained its phase change performance. Deployable on existing manufacturing workflows, the proposed process can offer a scalable pathway for producing phase-change gypsum boards.