Derivation of appropriate temperature change for application of phase change materials in building walls for energy reduction in Korean climatic conditions

Studies are underway to apply phase change materials (PCMs) to buildings to reduce energy consumption. PCMs can be expected to achieve energy savings by exploiting their high latent heat capacity and time-lag phenomenon, slowing down the heat transfer within the structure, and accumulating and releasing latent heat. This study analyzed the appropriate melting point and energy-saving effects based on changes in external climate conditions, attachment location, and PCM properties (thickness and thermal conductivity) through building energy simulations. Climate data were quantitatively categorized into climate zones based on heating degree hours, cooling degree hours, and insolation, and a total of 14 climate zones were proposed. The appropriate melting point based on climate was evidently more effective for cooling than for heating, and external attachment was proved to be more advantageous. As the thickness increased, the appropriate melting point decreased, and the energy-saving effect remained effective. The thermal conductivity increased with the graphite content by 0.90–2.37%, and the appropriate melting point also changed by 0.72–0.91 °C. As the thermal conductivity increased, heat was rapidly transferred within the PCM, altering its energy-saving effect by 0.18–3.35%.