# Items, Assets, EnergyAssets and Services ## Items The Item class represents an abstract item. Items can have an id, a name, a short name and a description. The following classes are derived from the item class: * Assets: an Asset is an Item with a physical representation. * Services: A Service is a logical Item. ## Assets Assets are all physical items in the EnergySystem. Assets can have a location, a geometry, commissioning and decommissioning dates, cost information (investment, installation and operation and maintenance costs). Assets are contained by Areas. ## EnergyAssets An EnergyAsset is an Asset with one or more ports allowing to model connections between assets. The EnergyAsset class is subdivided into 5 categories: * ProductionAsset: e.g. wind turbine, solar panel, geothermal source * ConsumptionAsset: e.g. electricity demand, heat demand, gas demand * StorageAsset: e.g. battery, buffer * TransportAsset: e.g. electricity network, gas network, cable, pipe, transformer, heat exchange * ConversionAsset: e.g. gas heater, heat pump, power plant, CHP, fuel cell ## Services Example Services are demand response services and aggregator services. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://energytransition.gitbook.io/esdl/esdl-concepts/data-types/items-assets-and-energyassets.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.