In 2019, the cement industry used 280 million tons of oil equivalent, contributing to 7% of totalindustrial energy consumption. This resulted in 2.4 billion tons of CO2 emissions, constituting26% of the industrial sector’s CO2 output and 7% of global energy-related emissions. On theother hand, It is affordable, safe, and readily available, thanks to its construction error resistance. C3C is a company that takes advantage of waste concrete that has been produced and useit to mold concrete blocks that has different functions. This is a big environmental benefit. Themain function of these blocks has been to function as temporary or permanent partitions walls orsafety walls for accidental loads. The aim of this study is to investigate the feasibility and performance of a temporary office structure that is built majorly out of these C3C lego blocks froma comfort, stability and sustainability point of view. This data aids construction professionalsseeking cost-effective alternatives to traditional methods. Retrofitting and cascading offer economic and environmental benefits. Our goal is to discover innovative, sustainable constructionapproaches for future generations. The results show the importance of insulation positioning forthe comfort point of view. To ensure stability and analyse if the separation of the blocks occur,four RFEM models are made with focus on the tensile stresses and uplifting deflection of thewalls. In conclusion, this study provides ideas on how to design a temporary structure usingC3C lego blocks.Keywords: Concrete blocks, C3C blocks, FE models, life cycle analysis, mechanical connections, CO2 emissions.