Heat storage performance of concrete brick walls with phase change materials enhanced with recycled industrial waste

A substantial portion of carbon emissions originates from the energy consumed by buildings, highlighting the need for efficient energy storage solutions that maintain indoor thermal comfort. This study develops a building-integrated thermal energy storage system using a composite PCM incorporated within concrete bricks. The composite consists of paraffin wax enhanced with locally sourced waste fly ash and metal slag particles to enhance thermal performance. The composite stores thermal energy during periods of high temperature and releases it during cooler conditions, thereby managing temperature fluctuations and shifting peak thermal loads. Characterization methods, such as FTIR, thermal conductivity, DSC, and thermal reliability analysis with 1 wt% of filler particles. FTIR analysis shows good compatibility among the constituents. DSC analysis shows a similar trend for the composites as for paraffin wax. DSC analysis and FESEM analysis after thermal cycles show good retention capacity. The developed composite is filled in a slotted concrete block to test its effectiveness as an insulating material by storing the excess heat in a developed building material testing setup. The results demonstrate a 20% reduction in peak temperature and a 42% decrease in the overall heat transfer coefficient, indicating effective thermal energy storage. The minimum heat flux value is recorded for the composite with metal slag particles, followed by the PCM with fly ash. The developed system acts as a passive thermal energy storage unit, enhancing energy efficiency, reducing cooling demand, and promoting the sustainable reuse of industrial waste materials.