Numerical investigation of phase change materials (PCM) optimal melting properties and position in building elements under diverse conditions

Abstract

The increasing popularity of phase change materials (PCM)-enhanced building products has initiated a scientific discussion concerning specific aspects of their applicability. This study aspires to provide justified answers to the research question of the optimal position of PCM into the building envelope, with emphasis on vernacular buildings, as well as to enlighten aspects of the appropriate melting behaviour of PCM materials. Parameters directly affecting the operation of the PCMs, namely their position within the building envelope, the external environmental conditions and the prevailing interior environmental conditions, have been investigated under diverse climatic conditions with the use of finite element method (FEM). The probability density function (PDF) of the temperature distribution at specific locations within the building envelope, at which realistically PCM layers can exist were derived, revealing the fact that in the case of non-conditioned indoor spaces, the PCM layer should actually be incorporated into the inner surface of the wall. The analysis was also conducted for different orientations and locations of the European continent, providing sufficient answers concerning the appropriate melting temperature of PCMs in the case of non-conditioned buildings. The environmental assessment of building envelopes incorporating PCM building products has also been examined, delivering the energy pay-back time of the PCM-enhanced building products.