In many industrial contexts, buoyancy driven flows are the only cooling strategy in case of breakdown of the forced convection cooling system. In order to study those flows in a simplified configuration, a buoyancy-driven flow is generated inside a cubic enclosure by a partially heated block (Ra = 1.4E9). The flow is studied experimentally in the vertical median plane, in the part of the enclosure where the flow is generated i.e. close to the heated side of the block. Velocity elds, mean proles and RMS statistics are analyzed. The results show the presence of boundary layer ows with a central zone nearly at rest and stratied. RMS velocities are intensitied with elevation.