1. A system useful for monitoring resource flows at a number of devices, the system comprising: at least one sensor configured to detect a flow rate and/or a change in a flow rate at said devices; a receiving unit configured to receive data from said at least one sensor; at least one meter configured to measure an overall flow for at least a part of the devices; and a calculation module configured to receive information from the at least one sensor and the at least one meter, wherein the calculation module comprises a mathematical statistical model configured to estimate and/or predict flow of resources and/or performance of at least a selection of the devices.