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I am guessing that zone = B001 is a zone with a ThermostatSetpoint:SingleCooling object? If so, you can disregard the warning. If not I would like to see your input file. Click on my name for my email address.

Regarding the high conductivity material, the model checks the against a thickness threshold and then issues the warning you show. The thickness threshold is a function of the zone time step specified in the input file. You can check the math here to see how your material compares to the checks here and make adjustments as necessary.

Alpha = Conductivity(Layer) / (Density(Layer) * SpecificHeat(Layer));
if (Alpha > HighDiffusivityThreshold(=1E-5)) {
    DeltaTimestep = TimeStepZoneSec (= 60 * 60/Timestep);
    ThicknessThreshold = std::sqrt(Alpha * DeltaTimestep * 3.0);
    if (Material(CurrentLayer).Thickness < ThicknessThreshold) {

In your input file:

Timestep,4;

I am guessing that zone = B001 is a zone with a ThermostatSetpoint:SingleCooling object? If so, you can disregard the warning. If not I would like to see your input file. Click on my name for my email address.

Regarding the high conductivity material, the model checks the against a thickness threshold and then issues the warning you show. The thickness threshold is a function of the zone time step specified in the input file. You can check the math here to see how your material compares to the checks here and make adjustments as necessary.

Alpha = Conductivity(Layer) / (Density(Layer) * SpecificHeat(Layer));
if (Alpha > HighDiffusivityThreshold(=1E-5)) {
    DeltaTimestep = TimeStepZoneSec (= 60 * 60/Timestep);
    ThicknessThreshold = std::sqrt(Alpha * DeltaTimestep * 3.0);
    if (Material(CurrentLayer).Thickness < ThicknessThreshold) {

In your input file:

Timestep,4;