1. A system useful for monitoring resource flows at a number of devices characterized by a latent stochastic process, the system comprising: at least one sensor selected from the group consisting of piezoelectric sensors, induction sensors, temperature sensors, and lux sensors, configured to detect a flow rate and/or a change in a flow rate at said devices, wherein said at least one sensor is attached non-intrusively to said devices, and wherein said at least one sensor is configured to wirelessly communicate data; a receiving unit configured to wirelessly receive said 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 is in communication said at least one sensor; wherein said calculation module comprises a mathematical statistical model, wherein the mathematical statistical model is configured to estimate and/or predict flow of resources and/or performance of at least a selection of the devices based on data from the at least one sensor and from the at least one meter; wherein the calculation module is further configured to calibrate said at least one sensor based on said mathematical statistical model operating on said information from said at least one sensor and said at least one meter; wherein the data from the at least one sensor and from the at least one meter at time t are given as a vector (Y t ), wherein the latent stochastic process at time t is a vector (θ t ), wherein the mathematical statistic model uses a noise vector (ε t ) of the data from the at least one sensor and from the at least one meter at time t and a noise vector (ϑ t ) of the latent stochastic process at time t, and wherein a statistical distribution of the noise vectors (ε t , ϑ t ) is estimated based on the data from the at least one sensor and from the at least one meter.