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. DOAS system. 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

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 system. 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 Linkhere: https://github.com/jugonzal07/stack_overflow_questions/tree/master/unmet_hours/density_of_air

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

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 system. 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 Also, I'm unsure how best to share an IDF on this site. Any recommendations would be found here: https://github.com/jugonzal07/stack_overflow_questions/tree/master/unmet_hours/density_of_air

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

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 system. 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 model seems fine. Has anyone ran into this before? Thanks.

Also, I'm unsure how best to share an IDF on this site. Any recommendations would be appreciated.

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 system. 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 one seems fine. Has anyone ran into this before? Thanks.

Also, I'm unsure how best to share an IDF on this site. Any recommendations would be appreciated.