Cardinal orientation and melting temperature effects for PCM-enhanced light-walls in different climates

The use of Phase Change Materials (PCMs) in buildings, aimed at peak shavings and energy savings, has a long history and many applications. In the last decade, the use of PCMs embedded in thermal insulation layers for building envelopes become an interesting option for lightweight structures. Nevertheless, the possibility of profitably exploiting the thermal properties of PCMs is strongly affected by the harmonised combination of the parameters that determine the thermal consumption of the building. In order to analyse the effects of a PCM insulation layer in detail, this paper presents a complete dynamic model of a typical lightweight wall, containing a layer of PCMs, using a thermal model which also considers the hysteresis of specific heats. Five different cases were evaluated to study the effect of PCM positioning on energy utilisation in two different climates (Würzburg, Germany and Denver, USA), considering the effect of solar radiation on differently oriented walls, in summer. Results confirmed that the strong non-linearity of the PCMs’ behaviour and of the weather boundary condition deeply affect the thermal performance of the building, being the main reason for this effect an increase of the thermal capacity of the PCM layer and the external temperature.