1. A method for organizing and retrieving energy related information for a plurality of real world objects, the method comprising: defining in each real world object a number of information types, each information type representing a different kind or kinds of energy related information related to each real world object, wherein the information types comprise any one from the group of: electricity consumption, electricity production, gas consumption, efficiency, energy consumption, energy loss, and CO 2 emission, energy loss, specific fuel consumption, gas consumption, steam consumption, total energy consumption, energy cost, reactive power consumption, reactive power production, power quality and contribution, availability, providing for each real world object one or more predefined interfaces, adapted for retrieval from the real world objects of information of said information types, wherein each interface comprises at least one property denoted value that returns a value of a defined information type, providing process objects, representing the real world objects, providing information objects comprising information related to the real world objects and associating the information objects with related process objects, wherein each process object is associated with at least one information object, wherein the interfaces retrieve information of at least one of said types, wherein similar information types have similar predefined interfaces such that information of the same type is accessed in a same way for each information object independent of the process object that is a source of the information, arranging said process objects in a hierarchal structure comprising more than one level, so that the process objects obtain a parent-child relation, forming connections between information related to similar process objects, process objects at similar hierarchical levels or similar information types from different process objects, receiving and storing information about where to find the source or sources of the information to be retrieved via said interfaces of the information objects, wherein the interface of the information object corresponds to the interface for the information retrieved, selecting a set of information objects, a type of information, and an arithmetic operation, performing the arithmetic operation on the information for the set of information objects, and providing, upon request, information of a selected type for a selected information object via said interface of the information object, wherein the information relates to power management systems, maintenance systems, process control systems, or systems for process simulation and optimization.