This study presents a comprehensive analysis of environmental performance and circularity of various external wall compositions, examining their life cycle across production, construction, use, and end-of-life phases. Utilizing Life Cycle Assessment (LCA), the study assesses the environmental impacts of different wall structures, adopting a functional unit of one square meter of wall structure over a 50-year service life, considering equivalent thermal resistance and load-bearing requirements. This study further investigates the application of circular economy principles, emphasizing material flows, design strategies, and the necessary systemic changes to circular building practices. The findings reveal that the most significant contributors to Global Warming Potential (GWP) are the load-bearing structures of the wall, namely burnt brick and aerated concrete. Perforated burnt brick contributes to GWP by value of 144 kg CO2e/m2, aerated concrete brick 9.56 kg CO2e/m2, sand-lime brick 301.71 kg CO2e/m2. All the bricks used achieve a 25% circularity score because of 100% virgin materials are used and 100% of the waste is moved to downcycling. The highest emissions are also achieved by EPS thermal insulation and silicone plaster. The circularity score of plasters when placed in landfill at the end of their life is 0%, however if we recycled the plaster its circularity score would be 50%. The circularity score of the external wall compositions ranged from 20% to 77%. Changing the end-of-life phase increased the lowest circularity score composition by 9% and reduced emissions by 1.4%. The highest costs are quantified for the B6 energy consumption phase for transparent wall compositions. The research highlights the need for a coordinated transformation in the construction industry, integrating technical, economic, and social innovations to enable closed-loop material cycles and reduce environmental impact.