Error in Simulation! "Surface temperature instability in room"

[JulesAA]

Hi,

I tried to simulate a simple building and the following error appears:

Error: Surface temperature instability in room CL000000. Possible
remedies: add thermal capacity to construction CEIL-D; reduce time
step; set control radiant fraction to 0; check gain and ventilation levels;
reduce MacroFlo opening areas.

I tried to run the simulation after deleting room CL000000, but the same problem occurred then for the next first room in the list. So, I understand that the problem is more general, not only of this specific room.

I tried all the potential remedies, but nothing happened.

Note that the geometry and the templates were imported and assigned from another project that I created, where the simulation can be run normally!

Please help!

[farahghanem]

this usually happens when you have lightweight constructions assigned and try to run a simulation with a time step too wide to properly calculate the thermal transfer.

Check your constructions and try lower sizing and simulation time steps.

[JulesAA]

Thank you!

Smaller time steps was the solution!