EnergyPlus 8.9 error: PsyRhoAirFnPbTdbW: RhoAir (Density of Air) is calculated <= 0

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Hi all,

I have a school modeled in EnergyPlus 8.9 with a unitary multispeed heat pump and an EMS used to simulate a DOAS. When ran in a milder climate like Seattle it runs just fine, but when ran in Chicago I get this Density of Air issue:

** Severe ** PsyRhoAirFnPbTdbW: RhoAir (Density of Air) is calculated <= 0 [-384.79728]. ** ~~~ ** pb =[98725.00], tdb=[-274.04], w=[0.0000000]. ** ~~~ ** Routine=CalcMultiSpeedDXCoilHeating, Environment=RUN PERIOD 1, at Simulation time=07/01 00:34 - 00:35 ** Fatal ** Program terminates due to preceding condition.

Some cursory google searches say this error happens more frequently with buildings that have incorrect U-values for one of their envelope components but this model's U-values seem fine. Has anyone ran into this before? Thanks.

Files can be found at this Github Link

• IDF file
• ERR file
• HTML for 2 month simulation