Thermal analysis of multi-layer walls containing geopolymer concrete and phase change materials for building applications

A numerical model based on the finite differences method was developed to analyze the effect of seasonal variations, human comfort temperature, and wall design on the thermal performance of a single house dwelling in the climate conditions of Oslo (Norway) utilizing multilayer walls containing phase change materials. Special attention was given to the addition of an insulating layer and on variations of the assumed human comfort temperature, since these factors have received little attention previously. The thermal performance was found to be significantly improved by integrating microencapsulated phase change materials (MPCM) into geopolymer concrete and by adding pure phase change materials (PCM) to multilayer walls. Optimum conditions (thick PCM layer and thin insulating layer) resulted in an annual energy reduction of 28–30%. PCM was found to be more effective when it was located closer to the outdoor environment. Increasing the thickness and reducing the thermal conductivity of the insulation layer significantly decrease the energy consumption of a heating and cooling system, but reduces the effectiveness of the high heat storage capacity of the MPCM/PCM. The multilayer walls exhibited best performance in summer, with up to 32% energy reduction in the lower range of the considered human comfort zones (18 °C).