[TRNSYS-users] Active Layer Matlab Model

Dear TRNSYS users,

I am modelling a 3D multizone building with Type 56. My building has exotic TABS which cannot be defined with the standard TRNSYS model, therefore I am modelling them in MATLAB with an adjusted RC model.

My TABS lay between the first and second level (in the floor of the second level/ceiling of first level). Thus, there is one heat flux going into each room (above and below). I tried to input my heat flux from the TABS MATLAB model as a heat gain to the inside surface of the floor of the second level and to the ceiling of the first level. These two surfaces are modelled as massless layers with a maximum R value, to prevent any heat flux going through, as all heat flux calculations going through these layers are calculated in my MATLAB model. I have attached a picture showing the setup.

Unfortunately I am getting covergence errors in the first time step.

I don't want to input my heat fluxes directly to the air node, as I would like to take advantage of TRNSYS sophisticated radiative and convective heat transfer calculations. Additonally, I think this wouldn't be precise as the surface temperature of my TABS surfaces are greatly affected by its heat flux.

Any suggestions what the problem could be or how else I could implement this?

Thank you for your helps and best regards,

Daniel Weber