As a contribution of the building sector to mitigating the effects of climate change, namely rising sea levels, floods, droughts, cyclones, sandstorms, retreat of arable land and forest fires, in anticipation of the objectives of the Paris Agreement, on the one hand, and energy efficiency on the other hand and the development of sustainable and environmentally friendly building materials, this paper presents the thermal characterization of compressed earth blocks using two clays used by the population of MARADI in Niger for the construction of habitats. The clays are mixed with sand (10%), cement (4%) and varying proportions of millet waste from 0% to 10%. The study shows that the thermal conductivity of composites decreases as the amount of millet waste increases. Conversely, the thermal resistance increases with each addition. Conductivity values varies from 0.268 W. m<sup>−1</sup>.K<sup>−1</sup> to 0.644 W. m<sup>−1</sup>.K<sup>−1</sup> for MARADAWA clay (BAM) samples and from 0.275 W. m<sup>−1</sup>.K<sup>−1</sup> to 0.723 W. m<sup>−1</sup>.K<sup>−1</sup> for Jiratawa clay (BAJ) samples. This represents a reduction of 61.96% for Jiratawa clay and 58.39% for MARADAWA clay compared to non-added materials. Composite materials are more effective in terms of thermal insulation.