The growth of different sectors in developing countries requires a tremendous amount of energy, making energy an important factor leading to environmental and economic concerns toward energy saving. A total of 33% of the energy consumed comes from buildings, and 50% of this energy is lost via the walls. As a result, the intended thermal comfort criteria and the properties of the building envelope determine the total energy consumption of a material. A lower thermal conductivity rating can help to reduce this temperature loss even more. Therefore, it was intended in the research initiatives to create walling material, such as bricks, with low thermal conductivity without efflorescence. The ability of bricks to absorb the vibration helps them to better sustain under the seismic load. The composite brick of a dimensional size of 190 x 90 x 90 mm is developed with fly ash, polymer, glass powder, and gypsum (CaSO4.2H2O). The designed brick contains fly ash as the matrix material, plastic waste such as HDPE and PP resin as the binder, glass powder as reinforced, and gypsum as the nanofiller. Thermal conductivity decreases from 0.23 - 0.15 W/mk as the polymeric concentration increases in the designed sample by 30%, 35%, and 40% polymer. On analyzing the DSC curve the degradation temperature is found to be 123.64 and 139.58 degrees C, 125.92 and 144.64 degrees C, 127.50 and 153.07 degrees C respectively, for 30%, 35%, and 40% of the polymer corresponding to endothermic and exothermic reactions with enthalpy 4.4808 J/g and 2.2012 J/g, 4.5976 J/g, and 2.31487 J/g, 4.6859 and 2.4337 J/g respectively. Introducing the plastic content in the designed sample caused a significant decrease in thermal conductivity and improved the resilience properties against earthquakes to bear more impact load and developed stress to the structure.