The paper considers the use of gas fired micro turbine generators (MTG) for trigeneration (combined production of electricity, heating, and cooling) applications in tertiary buildings. The importance of the adopted MTG technology is investigated, showing that the high electrical efficiency levels achievable by future advanced ceramic MTGs would improve dramatically the economic competitiveness of the application, as well as the primary energy savings and environmental benefits. Calculations are performed by the simulation code TRIGEN, capable of optimizing the plant operating mode in each time step and integrating the results over the entire year. The requirement of a “target” energy saving index on the optimization procedure is also addressed.