Master's Thesis Christian Sauren


Lifecycle efficiency analysis of heat supply systems in the building stock enabled by the Digital Twin concept

Design Approach Copyright: EBC Design Approach to implement a Digital Twin for HVAC systems throughout product lifecycle

Digitalization of energy systems easily enables the application of sophisticated control strategies increasing significantly operational efficiencies. Unlocking the entire potential, there is an urgent need to design systems carefully by simultaneous consideration of functional requirements and control strategies with digital interfaces in early development stages. Hence, the digital twin approach has proven great suitability for complex system designs.

Building energy systems are complex because of their nonlinear behaviour and stochastic environmental interactions. Regarding heating, ventilation and air conditioning systems (HVAC), it is important to be able to make robust and accurate statements for operating efficiency, despite the high level of complexity involved. However, their efficiency strongly depends on both component design and control strategy. Aiming for high efficiencies and unlocking untapped potentials, we apply systematically digital twin design (DTD) to HVAC systems.

For potential estimation, a digital twin prototype (DTP) of a ventilation system is being developed componentwise in Modelica to predict the physical behavior of HVAC systems. Both, the individual components and the overall system, require high simulation speed and accuracy so that physical and thermodynamic states can be estimated precisely in real time.

Verifying functionality and suitability of DTD, we set up a digital twin instance (DTI) by calibration the DTP against measurement data of the physical twin. In this purpose, a suitable calibration methodology is selected and applied. Both twins communicate via MQTT interfaces with each other. This enables DTIs to calculate realistic predictions based on live data. For the simultaneous investigation of different operating strategies, several DTIs simulating different scenarios form the digital twin aggregate (DTA). The aim is to create a software environment with Docker, in which the instances can be executed independently of system environment. By this means the operating status can be monitored at all times, the optimal operating strategy can be determined and operational efficiency of HVAC systems increases.

In conclusion, Digital Twins offer the opportunity to implement advanced model-based control strategies to HVAC systems. These allow the realisation of optimized operational management or predictive maintenance, by which potentials for increasing life cycle efficiency can be tapped.