The Smart Appliances REFerence (SAREF) ontology is a shared model of consensus that facilitates the matching of existing assets (standards/protocols/datamodels/etc.) in the smart appliances domain. The SAREF ontology provides building blocks that allow separation and recombination of different parts of the ontology depending on specific needs. The starting point of SAREF is the concept of device (e.g., a switch). Devices are tangible objects designed to accomplish a particular task in households, common public buildings or offices. In order to accomplish this task, the device performs one or more functions. For example, a washing machine is designed to wash (task) and to accomplish this task it performs the start and stop function. The SAREF ontology offers a lists of basic functions that can be eventually combined in order to have more complex functions in a single device. For example, a switch offers an actuating function of type 'switching on/off'. Each function has some associated commands, which can also be picked up as building blocks from a list. For example, the 'switching on/of' is associated with the commands 'switch on', 'switch off' and 'toggle'. Depending on the function(s) it accomplishes, a device can be found in some corresponding states that are also listed as building blocks. When connected to a network, a device offers a service, which is a representation of a function to a network that makes the function discoverable, registerable and remotely controllable by other devices in the network. A service can represent one or more functions. A service is offered by a device that wants (a certain set of) its function(s) to be discoverable, registerable, remotely controllable by other devices in the network. A service must specify the device that is offering the service, the function(s) to be represented, and the (input and output) parameters necessary to operate the service. A device in the SAREF ontology is also characterized by an energy/power profile that can be used to optimize the energy efficiency in a home or office that are part of a building.