Brick is the most basic artefact and plays a very important role in the construction of buildings. The construction industry is in need of easily available, economically feasible and green materials, as there is a scarcity of naturally available river sand. Use of iron ore tailings (IOT) is found to be very beneficial, and the addition of perlite as an admixture to improve its thermal properties is given scope for the development of non-fired thermal efficient bricks. Bricks were made using different proportions, by replacing sand with IOT from 30% to 60% at 10% interval, cement from 10% to 20% at 5% interval and Perlite at 2% and 5% of 230 mm × 112.5 mm × 75 mm dimensions. Based on laboratory experiments, the optimum percentage of mix to make bricks consisting of IOT, sand, cement and perlite was found to be 50%, 25%, 20% and 5%, respectively. Based on the positive laboratory results, further a pilot-scale study was taken up with IOT–perlite bricks. Two model rooms, one with IOT–perlite bricks and the other with conventional bricks were constructed to assess the effectiveness of thermal conductivity. The study proved that eco-friendly bricks by using IOT will have lower thermal conductivity, better strength and will be lightweight in structure.