T The building sector is a major contributor to energy consumption and greenhouse gas emissions in indonesia, accounting for approximately 50% of national energy use and around 30% of total emissions. this study evaluated the implementation of a techno-economic energy management system (enms) in a government building in jakarta through a combination of energy efficiency retrofits and rooftop photovoltaic (pv) integration. the methodology included an iso 50001–based energy audit, building performance simulation using designbuilder, pv system design with pvsyst, and economic feasibility analysis. the results showed that led lighting retrofits reduced lighting energy consumption by 38.14%, while air-conditioning optimization improved thermal comfort. a 24.75 kwp rooftop pv system generated 33,428 kwh per year and supplied 17.97% of the building’s electricity demand. overall, the integrated interventions achieved total energy savings of 37,587 kwh per year and emission reductions of 31.57 ton co₂ annually. economic analysis indicated that the project was financially feasible, with a positive npv, a 6% irr, an 8.18% roi, and a payback period of approximately 14 years. the integrated approach proved effective and showed strong potential for replication in similar public buildings