This work lies within the concept of positive energy buildings. The aim is to develop an activemanagement of local free energy (solar, air and earth) inside the envelops by convection heat transfer and by the use of phase change materials (PCMs) in order to store or release heat when needed. A 1D RC network simulation tool has been developed for different standard fronts including a solar air collector and a double skin faade (south frontage), leading to the thermal simulation of a room with different configurations, with or without PCMs integration and for ventilated envelops.