Use of PCM materials for the reduction of thermal energy requirements in buildings

The well-known insulation techniques of the building shell, if on the one hand ensure a reduction of energy requirements for winter heating, do not always allow a decrease in energy demand for the cooling of indoor environments and, in some cases, they cause an increase in thermal cooling requirements. For this reason it is necessary to use innovative passive techniques, which in summer are able to mitigate the indoor air temperature, thus limiting the use of air-conditioning plants, while in winter they contribute to achieving energy savings. Among the solutions recently introduced to reduce the buildings' energy requirements are the phase-change materials or PCMs. These are thermal storage materials with low melting/solidification temperature, able to store and release heat during the phenomena of phase transition, limiting the indoor air temperature variations within a building. The PCM, placed in the walls, floors or ceilings, limiting thermal fluctuations also allows a more rational use of the heat gains. Use of PMCs in summer, especially in locations characterized by a Mediterranean climate where the thermal energy requirement for cooling are comparable to those for heating is suggested. In this work, through the use of the simulation code TRNSYS vs. 17, the efficacy of current insulation techniques combined with the benefits obtained with the use of PCMs is evaluated, through analysis conducted on an existing building sample. The effects of a layer of PCM mounted on the internal vertical and horizontal opaque walls are investigated. A preliminary phase in order to achieve the best PCM melting temperature as a function of the conditioning season was conducted. The influence of the thickness of PMC on reducing energy requirement in winter and summer has also been investigated. The study, quantifying the reduction of building sample energy requirement respect to the case of the same building without PMC, has unequivocally confirmed that the PCMs represent an innovative technological solution to be used both in the existing building and on new buildings. In Mediterranean-type climate contexts, the most obvious benefits are found in the summer, and their use contributes substantially to the reduction of pollution produced by the residential sector.