The present study deals with the numerical analysis of free laminar convection within a square cavity whose vertical walls are kept at a constant temperature whereas the horizontal walls are thermally insulated, with the exception of a centered portion of the lower wall, which constitutes a heat source, whose temperature is greater than that of the vertical walls. Square blocks, subjected to an adiabatic boundary condition, are placed inside the enclosure. The latter is filled with air. The resolution of the governing equations is done by means of the finite volume method. The SIMPLER algorithm is adopted to deal with the velocity-pressure coupling. The study focuses on the influence of the presence of these blocks on heat transfer within the enclosure. The results show that the latter is reduced when the cavity is provided with these blocks and that their number plays a great role in the propagation of heat from the heat source.