In this study, fatty acid ester/building material composites as novel form-stable phase change materials (PCMs) were prepared by absorbing liquid fatty acid esters into porous network of conventional building materials. In the composite erythritol tetrapalmitate (ETP) and erythritol tetrastearate (ETS) esters were used as PCM for thermal energy storage, and cement and gypsum used as supporting material. The composite PCMs were characterized using scanning electron microscope (SEM) and Fourier transformation infrared (FT-IR) analysis technique. The SEM results showed that the esters were confined in the porous network of the cement and gypsum. Thermal properties and thermal stabilities of the composite PCMs were determined by using differential scanning calorimetry (DSC) and thermal gravimetric (TG) analysis techniques. DSC results showed that the melting temperatures and the latent heats of the prepared composite PCMs were in range of 21.6-32.3 degrees C and 35.9-43.3J/g, respectively. TG analysis indicated that the composite PCMs had good thermal stability. The thermal cycling test including 1000 heating and cooling process was conducted to determine the thermal reliability of the composite PCMs and the test results revealed that the composite PCMs have good thermal reliability and chemical stability. (C) 2011 Elsevier B.V. All rights reserved.