Integrating TRNSYS and CityGML in urban district simulations: A comprehensive case study in urban energy systems

To enrich the urban context, energy simulations are of great value, nevertheless, the task of dynamically simulating buildings requires different types of data and data enrichment processes. For this purpose, the use of the CityGML standard is of great importance, encompassing both geometric data, archetype data and construction data.

Therefore, the objective of this paper is to present a comprehensive workflow that automates TRNSYS simulations using the Grashopper PlugIn TRNLIZARD. This workflow integrates diverse data sources, including a CityGML model, streamlining the simulation process and advancing building performance simulation.

The workflow leverages Grasshopper’s capabilities within Rhino software to refine the geometrical data that comes from the CityGML. With CityGML data stored in a PostgreSQL database, PostgreSQL’s geometric functions are crucial for retrieving the correct data. This model allows the process to contemplate the building’s environment as well as the semi-automatic generation of window surfaces for the building if not defined beforehand in the model. Once processed, the data is transferred to modified TRNLIZARD components, enabling the generation of the necessary TRNSYS files for a final simulation. An additional testing step ensures the accuracy of these files.

As proof of concept, this workflow is tested on four contiguous buildings, each of which has different structures and characteristics. The results of the paper will include a test of the proposed workflow in a neighborhood in Palma de Mallorca (Spain) where a regeneration process and retrofitting of buildings are taking place. Furthermore, the results will offer comprehensive indicators related to both thermal comfort and energy demands. The study will analyze how the simulated energy performance of the buildings aligns with the comfort criteria required for optimal indoor environments, including temperature, humidity, and energy demands.

This case study aims to contribute to the development of Climate Positive Circular Communities by enhancing building performance and supporting the transition to net-zero energy and carbon targets, as well as healthy living environments.