In this paper, a heat emitter suitable for internal thermal renovation of buildings is experimentally studied. The proposed system consists of an insulation panel provided with a double skin open to the room at the top and bottom. These openings allow air to circulate freely between the room and the air gap within the double skin. A water/air heat exchanger is placed in the double-skin wall immediately above the opening at the bottom. This type of system is a simple solution to respond to internal thermal renovation needs, providing both insulation and low temperature heat emission. The experimental bench is mounted in a Passys cell designed for taking measurements in a controlled environment. The results showed that the chimney effect caused by the heat exchanger confinement induces an increase in air velocity and therefore an increase in power dissipation compared to a similar context without confinement.