Earthen construction is considered as an ecological construction offering many advantages in terms of adaptation to climate change and reduction of CO2 emissions from buildings. The choice of a building material implies a suitable construction technique and an appropriate architecture according to the environmental conditions. The objective of this work is to study the thermal performance of two cob materials, a material traditionally composed of clay, water and wheat fibres through numerical simulations. Two walls designed with clay and four other walls designed with cob (with 3 or 6% fibres) are studied in view of their application in modern wood-frame structures. To this end, the one-dimensional transient heat equation through single-layer walls of 15 cm and 25 cm thickness is solved using the finite element discretization scheme. The thermal properties used for the numerical simulation are experimental data obtained from samples fabricated in a laboratory. The simulations are performed using climate data from Montreal (Canada), Reno (USA) and Djibouti (Africa). The results of the wall simulation are evaluated according to the influence of local meteorological conditions on the interior surface temperature for each type of wall.