Abstract: An energy management system is disclosed having an in situ processing unit with a measuring unit capable of measuring a set of power related parameters over a main electricity cable. The system has a first processing unit capable of processing the power related parameters by applying a signature detection algorithm, for detecting an event relating to turning ON or OFF an electronic and/or electric appliance and for characterizing the event. The system also has means for transferring to a server a data packet having an output of said signature detection algorithm. The processing unit triggers the transfer of a data packet only in case such an event is detected. Also disclosed is a method for monitoring the use of electronic and/or electric appliances.