Thermal Performance Evaluation of Phase Change Material-Integrated Triple-Glazed Windows Under Korean Climatic Conditions

Passive design strategies incorporating phase change materials (PCM) provide effective thermal energy storage, improve indoor comfort, and reduce building energy demand. This study aimed to evaluate the effectiveness of partially filled PCM glazing systems in stabilizing indoor thermal comfort under Korean climate conditions, testing the hypothesis that partial integration can provide meaningful diurnal temperature regulation without compromising daylight access. Indoor air, interior and exterior glazing surfaces, and the PCM layer were monitored to evaluate heat transfer, while EnergyPlus simulations extended the analysis to seasonal conditions. The PCM model was developed using the Conduction Finite Difference (CondFD) algorithm and validated against experimental data, reliably reproducing dynamic phase change behavior. Field tests with a 28 °C PCM showed reductions in indoor peak temperatures of about 2.0 °C during daytime and increases of 1.5 °C at night. Under broader climatic simulations, the same PCM achieved up to 3.7 °C daytime reductions and 2.0 °C nighttime increases, depending on outdoor conditions. These findings highlight the potential of PCM-integrated glazing systems for adaptive thermal regulation in Korean climates and suggest broader applicability for passive cooling and heating strategies in buildings facing increasingly variable weather conditions.