A method for estimating the cost of a system over its predetermined life cycle includes estimating refresh and non-refresh costs for the system over its life cycle. By estimating the refresh cost, such a method allows one to select the most cost-effective implementation for the system by comparing the costs of different implementations. For example, if the system is to be installed in a submarine, one can select the most cost-effective system configuration for a given refresh rate, where the refresh rate coincides with the intervals at which the submarine is in port for service. Or, for a given system configuration, one can determine the most cost-effective refresh rate, and thus select the most cost-effective interval for servicing the submarine.