University campuses are among the largest institutional energy consumers in many cities, and their mixed building stock, variable occupancy and research-intensive loads make them both challenging and instructive settings for advanced energy management. This paper reports the implementation of digital-twin-based energy management on two university campuses, at Delft in the Netherlands and Kraków in Poland, and assesses the transferability of the approach to tropical campuses in Indonesia. On each campus a digital twin was constructed for a cluster of buildings by integrating building information models, a calibrated dynamic thermal simulation, metered energy data and sensor streams from building management systems. The twin was used to run real-time simulation of heating, ventilation, cooling and lighting demand and to generate control set-points and operational recommendations that were applied through the building management systems and through facility staff. Over one academic year, from September 2024 to August 2025, real-time simulation reduced building energy consumption by 17% across the participating buildings relative to a weather-normalised baseline, with reductions of 19% at Delft and 15% at Kraków, and without measurable deterioration in thermal comfort indicators. Savings arose mainly from occupancy-responsive ventilation and heating schedules, optimised pre-heating and improved fault detection. A transferability assessment is provided for tropical campuses in Indonesia, drawing on a simulation study for a building at Institut Teknologi Bandung, which indicates that the approach is applicable to cooling-dominated climates but requires adaptation of sensor strategy, occupancy modelling and integration with less standardised building systems.