The workshop has taken place on October 13-14, 2016 in Munich, Germany at TU München.
It is a joint international workshop of SI3D, OGC and TU München regarding the development of a CityGML Application Domain Extension for utility networks for energy, water supply, heating and other purposes.
More Information at http://en.wiki.utilitynetworks.sig3d.de
The Presentations are available at the wiki and also here for download