Distributed cogeneration systems, which supply both electric power and heat, offer many advantages over conventional central power stations for reducing the primary energy consumption. Micro gas turbines (μGT) have recently been developed as an electric power generation device for small-scale cogeneration systems. This paper reports the energy saving capability assessment based on the simulation of the annual fuel consumption in a micro gas turbine cogeneration system (μGT-CGS) including a boiler, a mechanical compression heat pump unit and an absorption chiller unit. Assuming the installation into three types of buildings (office, hotel and residence), the annual energy saving and the power supply fraction of the μGT-CGS are assessed. The results show that the advantage of the μGT-CGS significantly increases when the efficiency of μGT reaches 40%.