On April 3 and 4, 2019, the IBPSA Project 1 held its 3rd Expert Meeting. The meeting took place at RWTH Aachen, Germany, hosted by Christoph van Treeck and Dirk Müller, and was attended by 50 people from 21 institutes across 13 various countries.The meeting coordinated the ongoing work in the various tasks. A joint session between Tasks 1 and 2 highlighted the opportunities to integrate Modelica with the building construction process, with design tools and a digitization of the control design, deployment and verification process. A presentation about the semantic web for digital construction processes presented a framework that can be extended for more streamlined integration of currently isolated processes. Moreover, work continued on developing the BOPTEST infrastructure for comparison of advanced control sequences, and of DESTEST, a validation suite for district energy systems. For the application work package, a common template to report on case study has been developed.Further information can be found on the IBPSA Project 1 webpage.