Assessment of Thermal Performance of Modular Wall Panels with Salt Hydrate PCMS in Selected Classrooms of Gusaling Villegas in Pamantasan NG Lungsod NG Maynila

Classroom overheating is an increasing concern in tropical urban environments, particularly in educational buildings where elevated indoor temperatures may affect thermal comfort and learning conditions. This study evaluated the thermal performance of modular wall panels integrated with salt hydrate phase change materials (PCMs) as a passive cooling intervention in selected classrooms of Gusaling Villegas (GV) at Pamantasan ng Lungsod ng Maynila. A quasi-experimental research design was employed using one classroom equipped with PCM-integrated wall panels as the test room and another classroom without PCM panels as the control room. Indoor temperature and relative humidity were monitored over six testing days. The PCM system utilized sodium sulfate decahydrate as the salt hydrate PCM, with polyethylene terephthalate (PET) bottles serving as the protective encapsulation material. Differential scanning calorimetry testing was also conducted to examine the thermal characteristics and repeatability of the PET casing material. The results showed that the PCM-equipped classroom consistently recorded lower temperatures than the control classroom. Mean temperature differences across the six testing days ranged from 0.14°C to 0.67°C, while the maximum observed peak-temperature reduction was 0.85°C. The largest average temperature reduction occurred under the hotter conditions observed on Day 5. Relative time-lag effects were inconsistent, with measurable delays observed on some testing days but no consistent delay across the entire monitoring period. Relative humidity was only marginally affected, with an overall average difference of approximately 0.98%. Statistical analysis showed that the temperature data were non-normally distributed; therefore, a Mann–Whitney U test was employed. The test indicated a statistically significant difference between the temperature distributions of the test and control rooms (p