Experimental research is critical for the testing and development of new products as well as for the validation and verification of simulation models. In this paper, a novel way for testing various kinds of wall constructions, known as plug-and-play walls (PPW), is introduced. The PPW concept provides the flexibility to test most kinds of wall constructions in real time. It allows for the faster installation and dismantling of the test walls. The use of the PPW concept was demonstrated by evaluating the thermal performance of a thin phase change material (PCM) layer, herein referred to as “PCM thermal board (PCMTB).” The results showed that the average daily heat transfer reductions were 27.4% and 10.5% for south and west facing walls, respectively, and the average heat flux reductions when the heat fluxes of the control walls were at their peaks were 67.0% and 80.2% for the same orientations, respectively. It was demonstrated that the integration of a thin PCM layer also delayed the peak heat transfer rate per unit of wall area on an average of two to three hours.