Insulation materials are essential for minimizing energy use, enhancing thermal comfort, and minimizing greenhouse gas emissions in buildings. However, the insulation materials sector may have a considerable environmental impact. This study adopts a life cycle assessment (LCA) methodology to compare the environmental impact of four widely used insulation materials; extruded polystyrene, expanded polystyrene, rock wool, and glass wool. Without considering the use and end-of-life disposal stages, the LCA approach assesses the environmental impact of insulation materials from the cradle to the gate, including raw material extraction, production, and transportation. The study analyzes the Ibny Baitak project in New Assiut City as a case study to apply the LCA of insulation materials scenario and calculate their environmental impact.Extruded polystyrene, rock wool, and glass wool have the lowest environmental impact, according to the study's findings, while expanded polystyrene is the most harmful. Concerning the midpoint result, the XPS has recorded 4.35[kgco]_2 e and the EPS has pointed to 3.96[kgco]_2 e. As for the endpoint result, the XPS insulation material has recorded the highest adverse impact compared to other materials by 1.61 mt. The EPS came in the second rank by 1.24 mt, then the rock wool by 0.55 mt, and finally, the glass wool by 0.33 mt.The results imply that a building's environmental effect over its lifetime can be considerably impacted by the material used for insulation. The study's findings can help architects, engineers, and construction professionals choose the best insulation for energy-efficient buildings.