HVAC models coupled with hygrothermal building simulation software

This paper describes the integration of HVAC simulation models, developed with the multi-domain modeling language Modelica, into the hygrothermal building simulation software WUFI® Plus. With the existing software a hygrothermal building simulation, considering heating, cooling and air conditioning as ideal systems, can be performed in a user friendly way. Without detailed HVAC models, the software calculates the heating, cooling, humidification, dehumidification and ventilation demand which is necessary to keep the indoor climate in user defined design conditions. This output can be used for further investigation and sizing the plant equipment. However, a direct interaction between the detailed building model and the building equipment was not possible. This is improved with the newly developed Modelica HVAC models. They were exported via the common Functional Mock-up Interface (FMI), which was analyzed to assess the most effective coupling strategy. The FMI is the definition of an open interface between different software systems. The realization of a noniterative coupling algorithm is illustrated by means of a simulation example. Furthermore, the implementation of the HVAC models into the hygrothermal building simulation program is validated using the results from a Modelica simulation environment as reference.