Assessment of Two Methods of Enhancing Thermal Mass Performance of Concrete Through the Incorporation of Phase-Change Materials
Abstract
According to the IEA Technology Roadmap on Energy Efficient Building Envelopes, buildings are responsible for more than one third of global energy consumption, with space heating and cooling consuming 33% of this energy, and increasing to 50% in cold climates. Using the mass of a building to store heat and/ or cold can reduce the demand on the auxillary heating and/or cooling systems and hence reduce the overall energy demand of the building. In this study the thermal storage capacity of concrete was actively enhanced by integrating phase-change materials (PCMs) which provide a high latent heat storage capacity. Two methods of incorporating PCMs into concrete were used to form PCM/concrete composite panels. The first type of panel was formed by adding microencapsulated paraffin to fresh concrete during the mixing process. The second panel was formed by vacuum impregnating butyl stearate into lightweight aggregate which was then included in the concrete mix. The aim of the study was to compare the thermal behaviour of both PCM/concrete composite panels to a control concrete panel and to evaluate which method of PCM incorporation is the most effective at improving thermal mass characteristics in the context of a thermal energy storage system for space heating/cooling in a building. The panels containing PCM displayed significantly greater thermal storage capacity, despite having reduced thermal conductivity and density. The study concluded that the panel containing lightweight aggregate/PCM composite is more effective at providing additional thermal storage, particularly within the first 100mm of depth of an element of structure.
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