A power and energy management system, PEMS, architecture for managing power consumed by a plurality of power devices on a network, the architecture comprising: one or more local supervisors (11, 12, 13) each arranged to be connected in digital communication with one or more of the power devices (10) on the network; each local supervisor comprising: an input (CONTROL ERROR) to receive a control error signal indicative of a difference between the power consumption of the one or more devices and power available on the network for those devices; a watchdog module (120) configured to receive the control error signal and to determine from the control error signal whether there is a need for PEMS action on the network; a status monitor (130) configured to obtain information as to the operating status of the one or more power devices; a coordinator module (150) configured to define a coordination strategy for operating selected devices of the one or more devices based on the determination from the watchdog module and the information obtained by the status module; and a control action module (160) arranged to provide a set point to selected devices of the one or more devices to operate according to the coordination strategy determined by the coordinator module.