Flame‐Resistant Phase Change Material‐Integrated Clay Bricks for Enhanced Thermal Energy Storage and Thermal Buffering

ABSTRACT The incorporation of phase change materials (PCMs) into building components has attracted considerable attention as a passive approach for improving thermal energy storage and reducing heat transfer through building envelopes. However, the practical application of organic PCMs is often limited by leakage during phase transition and inadequate fire resistance. In this study, a flame‐resistant PCM composite was developed using a polyethylene glycol (PEG 600/PEG 2000) blend supported by polyurethane (PU) foam and protected by a chloroprene rubber coating containing kaolin as a flame‐retardant additive. The PCM system was subsequently integrated into perforated clay bricks by filling selected cavities to enhance their thermal performance. Differential scanning calorimetry (DSC) revealed a dual‐stage phase‐transition behavior, providing thermal energy storage over a broad temperature range. Thermal performance tests demonstrated that PCM‐filled bricks reduced surface temperatures by approximately 3°C–5°C, at highest temperature, compared with unmodified bricks, with the highest thermal‐buffering effect achieved when the PCM was positioned closest to the heat source. The composite also exhibited suitable leakage resistance, showing no observable leakage after exposure to 80°C for 3 h. Furthermore, the incorporation of 20 wt.% kaolin significantly improved fire resistance, reducing burning time by approximately 90% compared with the kaolin‐free coating. The developed PCM‐integrated brick combines thermal energy storage, leakage prevention, and enhanced flame resistance within a single system, showing its potential for passive thermal regulation and improved energy efficiency in building‐envelope applications.