In the arid regions, such as the city of Laghouat in the south of Algeria, the major preoccupation is how to build a well insulated building. While taking into account the now days requirements of « sustainable construction ». In this context the sand concrete alleviated by wood shavings, in order to improve its thermo-physicals properties, is an environmental and sustainable approach, which can be a promising alternative in the domain of the building industry. However, the importance of this study is limited to the experimental research of a better thermo-physical performance and to the reduction of the shrinkage while ensuring good mechanical properties. Finally, and in order to get closer results to the reality, a theoretical study by simulation is conducted in order to appreciate the thermo-physical behavior of the concrete studied for the construction of an exterior wall in a specific region. Two different parameters have been varied in this study: the thickness of the wall (with and without cavity) and the thermo-physical properties of the studied concrete. The results show that the thermo-physical properties of the concrete studied such: the thermal conductivity, the specific heat and the density have a great effect on the time lag ф and the decrement factor ƒ. Grater time lag and lower decrement factor minimize the effects of the outside environment on the inside one. The value of time lag and decrement factor for 20cm wall made by sand concrete elevated by wood shavings were 6hours, 0.305, and for the same wall with 5cm cavity were, 8hours, 0.084. The results obtained are useful for designing low energy consumptions buildings.