This paper investigates the environmental aspects and energy impacts of implementing a green roof system at the Hilton Watford hotel, utilizing Building Information Modeling (BIM) software (Revit) for 3D modeling and Insight for energy simulation. Following EN 15804:2012+A2:2019, the study employs Life Cycle Assessment (LCA) methodology, focusing on embodied and operational carbon. Environmental Product Declarations (EPDs), Inventory of Carbon and Energy (ICE) database, and the Royal Institution of Chartered Surveyors (RICS) guideline inform embodied carbon calculations. Results show the green roof system releases 263,839.56 kgCO(2)e as embodied carbon, while its sedum layer sequesters 211,468.12 kgCO(2)e over a 50-year lifespan. Energy efficiency analysis indicates a 3.3 kWh/m(2)/yr reduction in energy consumption, leading to a 112,130.31 kgCO(2)e reduction in operational carbon emissions, highlighting the environmental benefits of green roof adoption. The findings suggest a 0.35% mitigation of whole life cycle carbon emissions, with greater impact in situations of lower insulation effectiveness, showcasing the potential of green roofs in reducing carbon emissions. Additionally, the green roof incurs a minimal financial burden, constituting only 0.51% of the overall project cost.