<p>Sustainability-oriented solutions are essential to address the depletion of natural resources, solid waste accumulation, and high CO₂ emissions in the construction industry. This research focuses on the development of environmentally friendly green bricks by replacing high-carbon-footprint constituents with local, natural materials. Specifically, flax shives, a natural agricultural by-product, and marble powder, an industrial waste, were used as partial substitutes in the binder matrix. The natural fibers not only promote sustainability but also enhance insulation and reduce the environmental burden. The bricks were molded into rectangular specimens (60 × 100 × 200&#xa0;mm) and tested for thermal conductivity, moisture absorption, and compressive strength. The study evaluates the performance of these flax-shive-based green bricks based on three primary criteria: thermal insulation, porosity, and mechanical strength. Results indicate that incorporating natural fibers like flax shives provides a promising pathway toward sustainable, thermally efficient, and structurally viable construction materials.</p> Graphical abstract <p></p>