Phase change materials (PCM) have been widely implemented in buildings envelope as passive system as well as in storage tanks for active systems. A new promising technology has been designed to act as a hybrid system between the passive and active ones. The main idea is using the internal slab as a thermal energy storage system to cover partially the energetic demand both during heating and cooling periods. This innovative constructive system consists of a prefabricated concrete slab with PCM macro-encapsulated in small tubes and inserted in its hollows. A direct cross-flow heat exchange occurs between the air pumped into the slab and the PCM for conditioning purposes. A prototype has been implemented in a two storey house-like cubicle and has been tested under real conditions, where the slab becomes a thermal storage and supply component. The objective is to study the thermal performance of the slab and its components, in a theoretical analysis, as well as the suitability of the system in a Mediterranean continental climate. The concept was proved experimentally and compared to the theoretical results to demonstrate the potential of the technology. However, experimental results remarked the importance of a further investigation under real operating conditions. (C) 2015 Elsevier B.V. All rights reserved.