The building sector consumes more than 25% of energy consumption in Morocco. So, the reducing of the energy cost of building has become a necessity. In this context, the objectives of this work are to investigate the thermophysical properties and the energy performance of earthen walls made from three types of unfired clay bricks. This work is broken into two steps. In the first step the apparent thermal conductivity was obtained experimentally using the hot plate method. In the second step, the thermophysical properties obtained were used to calculate the decrement factor and the time lag of complete walls mad from these materials by solving the transient heat conduction equation with periodic loadings using the eigenfunction expansion and the integrating factor methods. The effect of the outer and inner combined convection and radiation heat transfer coefficient on these dynamic thermal characteristics was studied. The optimum thickness of the walls was also calculated. Finally, the effect of thermal insulation on energy performance of the walls was studied