Model and tool requirements for co-simulation of building performance

The use of building performance simulation (BPS) can substantially help in improving building design towards higher occupant comfort and lower fuel consumption, while reducing emission of greenhouse gasses. Unfortunately, current BPS tools do not allow inter-tool communication and thus limit a modeler to the component models available in the simulation software which happens to be used. A pragmatic way forward would be to enable co-simulation by externally coupled (legacy) tools. This means that each coupled software would represent only that part of the overall building and system configuration that it is able to model. The overall system is represented by the coupled models, which exchange simulation data during run-time. In this way, shortcomings of each tool can be overcome, and advantages of individual tools can be exploited. The work underlying this paper addresses co-simulation of building energy and heating, ventilation and air-conditioning (HVAC) models. So far, the research focus has been on thermodynamic issues such as which variables should be exchanged and at what frequency, rather than on mathematic or computer science aspects. This paper specifies and discusses the requirements for BPS software in order to enable co-simulation of building and HVAC system configurations.