Numerical study of thermal and energetic contribution of phase change materials integrated into external building walls

Abstract

The use of phase change materials (PCM) in the building sector has been the subject of several studies in recent years. Two main methods to integrate PCM in building envelopes, namely micro-encapsulation and macro-encapsulation, have been explored. Through dynamic modelling of residential dwellings, the impact of PCM integrated in external walls on thermal comfort and on heating and cooling energy has been studied. The Designbuilder software based on the Energyplus calculation engine was used to perform numerical simulations of the building's thermal behaviour using recently collected weather data in typical meteorological year format. A finite difference conduction solution algorithm is applied for the spatio-temporal discretization of the thermal equation and boundary conditions. Several variables that can affect the performance of the PCM were studied, namely the type of brick, the type of masonry, the thickness of the PCM and its melting temperature. Simulations revealed that macro-encapsulated PCM reduces indoor temperature fluctuations and thermal discomfort by 2.5°C to 3.7°C depending on the type of partition used and PCM location. For the semi-arid climate, the optimal melting temperature of the PCM allowing reducing cooling and heating energy is between 23 and 25°C. Simulations have also shown that increasing the thickness of a macro-encapsulated PCM beyond 30 mm does not lead to substantial energy savings.