At one side the indoor temperatures are important boundary conditions for the multi zone air flow model and should therefore not be defined on the basis of a user’s guess. On the other side the indoor air temperatures calculated by the thermal model strongly depends on the exchange of air between the zones as well as the outside. To link the two models and mutually use the results is the obvious consequence. In TRNFLOW the multi zone air flow model of COMIS is completely integrated into the thermal model of Type 56. This means that the exchange of data between the thermal and the air flow model is made internally and no longer by inputs and outputs. The proper classification of air flows (infiltration, ventilation, couplings) and temperatures to the air flow node resp. the thermal zones and the appropriate other model is automatically carried out by the program.

The input files of both models are kept in the existing formats (BUI, CIF) but are created by only one user interface witch is a TRNFLOW Version of PREBID. Air flow model data depending on time, like wind velocity or window opening factors are defined as inputs or schedules. Outputs like air flows or zone pressures are declared as outputs by means of
new NTYPES and can be written into an output file using a printer type or processed otherwise. The standard COMIS Output File (COF) is optionally also available.