Abstract: The apparatus and method of the present invention provides accurate consumption and efficiency data for a given system by taking into account many of the external factors described. The apparatus receives inputs from a number of different sources including environmental sensors, utility meters and other device sensors. The input data are transmitted to a central base-station that communicates the data to a remote server. The server uses the sensor data and calculates system performance values, for example energy consumption and cost, and compares these to a number of preset values, for example user defined targets or ‘Best-In-Class’ performance. The data are then available to a user online via a secure web-based interface.