Nowadays, the energy efficiency of buildings is one of the biggest preoccupations, due to the high negative impacts in the environment, economy and society. The utilization of phase change materials (PCM) in construction industry was been developed by several authors around the world. In this study, the connections between the PCM, energy efficiency and energy poverty are presented. The main PCM characteristics and an exhaustive description of the PCM application in buildings, more specifically in walls, floors, ceilings and glazed areas, are also presented.