Experimental Evaluation of Nano-encapsulated PCM Dosage in Cementitious Composites for Energy-Efficient Building Envelopes using RSM

ABSTRACT

The present study evaluates nano-encapsulated phase change materials (nano-PCMs [PCM-N]) incorporated into cementitious composites for thermally efficient building envelopes. Paraffin was encapsulated within a silica shell by a sol–gel route and incorporated into cementitious mixes at different dosages. Response surface methodology (RSM) based on a central composite design was used to optimize PCM dosage and curing time with thermal conductivity, latent heat capacity, and compressive strength as the response variables. Compared with the control mix, the PCM-N composite reduced thermal conductivity from 1.61 to 1.24 W/m·K, corresponding to an approximately 23 % reduction, whereas latent heat capacity reached 70.6 J/g at the highest dosage investigated. Thermal cycling results showed that the PCM-N system retained about 80–85 % of its initial thermal efficiency after 100 cycles, indicating better durability than the micro-PCM system. Under simulated solar loading, the PCM-N wall panel reduced the rear-face temperature from 42.6°C to 34.2°C, and building-scale simulation predicted an energy saving of 12.3 kWh with a carbon dioxide offset of 5.7 kg. The RSM analysis identified an optimal PCM-N dosage of 6.2 wt.% within the high-desirability region. These results demonstrate that silica-shelled PCM-Ns can improve the thermal regulation capability of cementitious composites, thereby maintaining acceptable mechanical performance for energy-efficient building envelope applications.