Prototyping the Next Generation EnergyPlus Simulation Engine
Michael Wetter, Thierry Stephane Nouidui, Christopher H. Brooks, Edward A. Lee, David M. Lorenzetti, Amir Roth · Building Simulation Conference proceedings · 2015
We describe the prototype of a next-generation implementation of EnergyPlus, DOE’s whole-building energy simulation engine. This new implementation breaks EnergyPlus into a set of component models with clearly defined input and output ports. It instantiates these components and their connections from the EnergyPlus input file ‐ thereby not disrupting applications that use EnergyPlus ‐ and then simulates them using a discrete event simulator. This new structure should allow EnergyPlus to evolve more rapidly and robustly by decoupling component modules from the numerical solver. It also allows models to be exported for integration with building control systems. We prototyped this new implementation using the open-source Ptolemy II framework. We encapsulated the computing modules as Functional Mockup Units (FMUs) for Model Exchange. The system of equations defined by the connection of the FMUs is integrated using Quantized State System (QSS) simulation, a novel method that partitions systems of differential equations and integrates them asynchronously, using step sizes that are based on the time rate of change of the individual state variables. We present a numerical example that illustrates the asynchronous integration and numerical benchmarks of a multizone building model with a radiant slab. We compare the computing time among our prototype, EnergyPlus version 8.2 and the Dymola 2015 FD01 Modelica simulation engine.