Fly ash bricks have lower thermal conductivity when compared to red bricks. This makes them conduct heat better, contributing to energy efficiency in the building. Their thermal conductivity can be 0.90-1.05 W/m2. With better insulation properties, it is suitable for areas with extreme temperatures and has high fire insulation properties. The thermal mass of fly ash is less than the red bricks. Hence, it helps save energy in the building and reduces the overall life cycle costs. Red Brick: