Effective reduction of electricity costs in conditioned buildings by using a cool storage installation is strictly dependent on optimal management and detailed prediction of the real operating conditions of the plant when designing the installation. Because of the multiplicity of causes which determine the final result, this is often very difficult to achieve. In this paper a monitoring test of a bank service central plant equipped with an ice storage cooling system is presented. The measured data show remarkable differences from design stage expectations. This confirms the necessity to always schedule a commissioning adjustment of this kind of system.