Introduction

The CityGML Energy Application Domain Extension (or, in short: Energy ADE) offers an open and standardised data model to facilitate multi-scale Urban Energy Modelling applications.

The current version, which is still in active development and at the moment is identified as version 2.0, is based on and builds upon version 1.0 of the Energy ADE, released in 2018, which has been already used in several national and international projects, mainly focusing on the simulation and computation of the building energy performance based on the integration of semantic 3D city models and other sources of information.

The technological innovations (e.g. the release of CityGML 3.0 in 2021) and the experiences and feedback collected since its release have contributed to forge several new ideas to improve and update the Energy ADE. Since 2024, work has been going on to harmonise and implement such ideas, with TU Delft and HFT Stuttgart being responsible for the first major development "sprint" in terms of conceptual data model (TU Delft) and implementation of the Java libraries (HFT Stuttgart). In the meantime, and in addition to the other DigiTwins4PEDs consortium members, several other partners have joined on a volunteer basis as enthusiastic contributors, early testers or technology enthusiasts.

This version of the Energy ADE is currently based on and extends CityGML 2.0, but its development already keeps in consideration its future porting to CityGML 3.0

The improved Energy ADE in a nutshell

The improved Energy ADE has a modular structure:

• The Core module defines additional attributes for the CityGML core::_CityObject and bldg::_AbstractBuilding classes. It also provides new abstract base classes for the other modules;
• The Building physics module defines additional attributes for the CityGML bldg::_BoundarySurface and bldg::_Opening classes. Additionally, it defines new classes to model the thermal hull of a building;
• The Occupancy module defines classes to model different usage zones and their occupants;
• The Devices module provides classes to model different types of energy-related devices that transform or store energy (e.g. solar collectors, storage devices, etc.);
• The Layered construction module enables the modelling of the composition of construction surfaces through different layers and their physical properties;
• The Resources module allows to model resources (energy, water, food, etc.) that an urban object may need, produce or store;
• The Urban function areas module allows to define spatial entities that allow to aggregate values;
• The Weather station module contains a class to model weather stations;
• The Schedules module includes different types of schedules;
• The Time series module contains classes for time series;
• The CodeLists, Enumerations and DataTypes modules contain support classes that are needed by all other modules.

Please refer to the documentation for more details, as well as a detailed description of the changes between the Energy ADE 1.0 and the current version of the Energy ADE.

Besides the conceptual model, available as UML diagrams (and the accompanying specifications), additional resources are available, such as:

• DDL scripts to set up the 3D City Database automatically using the ADE Manager
• An FME Workbench that allows to import CityGML + Energy ADE data into the 3D City Database
• Test datasets that focus on different aspects/modules of the Energy ADE
• A set of modelling rules and suggestions explaining how to use certain classes of the Energy ADE (please refer to the documentation)
• Additionally, Java-based libraries are being developed by HFT Stuttgart to add support to the citygml4j APIs and to the CityGML 3D City Database Importer/Exporter. For practical reasons, they are currently hosted here (citygml4j) and here (citydb). The latest package, including the Energy ADE 2.0 Java libraries for citygml4j, the 3DCityDB Importer/Exporter API, and the DDL scripts with schema mappings for full 3DCityDB Importer/Exporter plugin support, can be downloaded from here.

Further resources

• Are you struggling to read and understand UML? Download this UML crash course providing you with the basics to "survive" 😉
• Looking for a quick install guide to set up the 3DCityDB? Check out the Quick install guides for Windows, Ubuntu Linux and macOS!
• No idea on how to use FME with CityGML? Have a look at these introductory tutorials on FME and Reading and Writing CityGML data 💪

Contact person:

• Giorgio Agugiaro @ TU Delft

Main developers and contributors

• Giorgio Agugiaro (TU Delft, The Netherlands): Main developer
• Rushikesh Padsala (HFT Stuttgart, Germany): Main developer
• Prabitha Prabhakaran (HFT Stuttgart, Germany): Main developer
• Matthias Betz (HFT Stuttgart, Germany): Contributor
• Volker Coors (HFT Stuttgart, Germany): Contributor
• Thomas H. Kolbe (TU Munich, Germany): Contributor
• Jérôme Kämpf (Idiap, Switzerland): Contributor
• Camilo León-Sánchez (TU Delft, The Netherlands): Contributor
• Simon Raming (RWTH Aachen, Germany): Contributor
• Maxim Shamovich (RWTH Aachen, Germany): Contributor
• Zhihang Yao (HFT Stuttgart, Germany): Contributor

Early testers and technology enthusiasts

• University of Antwerp, Belgium
• IREC - Institut de Recerca en Energia de Catalunya, Barlellona, Spain
• Infosolutions Sp. z o.o., Poland
• Wroclaw University of Environmental and Life Sciences, Poland
• FBK - Fondazione Bruno Kessler, Trento, Italy
• AIT - Austrian Institute of Technology, Austria
• Municipality of Rotterdam, Netherlands
• Municipality of Stuttgart, Germany
• Municipality of Wien, Austria
• Municipality of Wrozlaw, Poland

License

The software resources available on this repository adopt the Apache License 2.0.
The documentation and the UML diagrams are released under the Creative Commons License CC BY-NC-SA 4.0

Citation

If you use the Energy ADE in scientific work, please cite one of our papers:

• Agugiaro, G., Padsala, R., 2025
  A proposal to update and enhance the CityGML Energy Application Domain Extension.
  ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci., Vol xxxx
  

• Gao, W., León-Sánchez, C., Agugiaro, G., 2025
  Data-driven energy simulations to evaluate positive energy district potential in Rotterdam.
  ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci., Vol xxxx
  

• Padsala, R., Falay-Schweiger, B., Hainoun, A., Coors, V., 2025
  A Data-Driven Urban Digital Twin Approach for Evaluating Positive Energy District Potential Using OGC Standards in Stuttgart.
  ISPRS Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., Vol xxxx
  

• Gebetsroither-Geringer, E., Padsala, R., Hainoun, A., Agugiaro, G., Biernat, S., Reber, A., Smetschka, B., Gao, W., Horak, D., Falay, B., Coors, V., 2025
  A participatory planning framework using urban digital twins supporting the co-creation of flexible, Positive Energy Districts.
  (Schrenk, M., Popovich, V.V., Zeile, P., Elisei, P., Beyer, C., Ryser, J., Trattnig, U., eds)
  REAL CORP 2025 Proceedings/Tagungsband, pp. 65-76. Graz, Austria, 14-16 April 2025. ISBN 978-3-9504945-4-9.
  Link to open-access PDF.
  

• Bachert, C., León-Sánchez, C., Kutzner, T., Agugiaro, G., 2024
  Mapping the CityGML Energy ADE to CityGML 3.0 using a model-driven approach.
  ISPRS Int. Journal of Geo-Information, MDPI, 13(4)
  Link to open-access PDF.
  

• Agugiaro, G., Benner, J., Cipriano, P., Nouvel, R., 2018
  The Energy Application Domain Extension for CityGML: Enhancing interoperability for urban energy simulations.
  Open Geospatial Data, Software and Standards, 2018 3:2. SpringerOpen, United Kingdom
  Link to open-access PDF.
  

Funding

Development of the new Energy ADE has started in spring 2024 within the European DigiTwins4PEDs project. The project is funded by the European Commission under the Horizon Europe Partnership scheme. The DUT Call 2022 also contributes to the Urban Transition Mission of Mission Innovation as part of the MICall 2022 initiative.

In addition to the DigiTwins4PEDs consortium members, several other partners have joined on a volunteer basis as enthusiastic contributors, early testers or technology enthusiasts.