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Hi,
I have modeled a floor structure with an active layer in type 56, and I use the timestep setting 0.1 hr when running the simulation. In spite of this setting, the actual timestep of the outlet temperature of the active layer seems to be 1 hr (not 0.1 hr) when I look at the simulation results (see attached capture). So it seems like the actual timestep in the simulation results is not influenced by the timestep setting. Why is it like this? Something wrong?
/Johan
@jolind I think what you are seeing is the building's time base, which is a bit like a time step. Type56 uses something called the conduction transfer function method in which a series of coefficients are computed to describe the transient behavior of walls (and floors and ceilings). The coefficients step backwards in time and give a relative importance to certain heat transfer drivers (such as the indoor/outdoor temperature difference). The coefficients are calculated for time intervals called a time base and often you can see a stepped behavior when you are looking at Type56 results especially if your simulation time step is much shorter than the Type56 time base. It is ideal to keep the time base and the time step equal but that is very often impossible. I have found that for most buildings you can use a time base of 0.25 hours and a 5-minute time step that minimizes the steps in the plotted results.
You can adjust the time base in TRNBuild's "outputs" window.
kind regards,
David
