1. A method for organizing and retrieving energy related information for a plurality of real world objects, wherein a number of information types are defined, each information type representing a different kind or kinds of energy related information, and the method comprises: providing one or more predefined interfaces, adapted for retrieval of information of said information types, providing software objects, representing the real world objects, having at least one interface for retrieval of information of at least one of said types, based on said one or more predefined interfaces, arranging said software objects in a hierarchal structure comprising more than one level, so that the software objects obtain a parent-child relation, receiving and storing information about where to find the source or sources of the information to be retrieved via said interfaces of the software objects, selecting a set of objects, a type of information, and an arithmetic operation, performing the arithmetic operation on the information for the set of software objects, and providing, upon request, information of a selected type for a selected object via said interface of the software object.