On the placement of a phase change material thermal shield within the cavity of buildings walls for heat transfer rate reduction

PCMs (Phase change materials) are used to enhance the thermal storage capacity of building walls, decrease indoor air temperature fluctuations, and shift peak heat transfer rates to off-peak times. PCM location within building walls is recognized to be critical for the optimum performance of the system. One possible integration of the PCM into a wall could be via a PCM-layer or “shield,” herein referred to as “PCMTS” (PCM Thermal Shield). A prototype PCMTS was developed and its thermal performance was evaluated in three different locations within the cavity of a typical North American residential wall system using a dynamic wall simulator in this paper. The experimental results showed that, compared to a wall without a PCMTS, the peak heat fluxes were reduced by as much as 11% when the thermal shield was placed in the inward-most location next to the internal face of the gypsum wallboard within the wall cavity. The PCM thermal shield produced only small effects on the peak heat fluxes when it was placed half way between the enclosing surfaces of the internal cavity of the wall and almost no effect when it was placed next to the internal face of the outermost layer of the wall.