This paper proposes an automated commissioning method for air-conditioning systems through comparing the measured energy consumption with the simulated energy consumption, which is simulated using a model newly developed through fitting manufacturer’s specification data. This commissioning method is verified using a Gas-engine Heat Pump (GHP) air-conditioning system. The results show that this method can verify whether a real air-conditioning system is performing in conformity with the design intent or not. Finally a commissioning case is studied using the commissioning method proposed here.