[Bldg-sim] Severe errors for Fan Power modelling of VAV system in Energyplus

[Alvaro Urrutia]

Dear all:****

 ****

In a baseline building modeling for LEED EApr2 documentation, I have some
troubles with the simulation reports that shows  unusually high amounts of
severe errors (over 1000);  when I try to model System Fan Power according
G3.1.2.9. and procedure proposed by James V Dirkes II, PE in a previous post
(pro-rating fan power to supply/ret​urn fans per 90.1-2007?).****



I am concerned if we can be observed by LEED reviewer team about this severe
warnings.****



Simulation details:****



-Baseline model consist of six-levels building for typical office usage
(8000m2 area approx.)

-HVAC system type 8, VAV with PFP zones according ASHRAE 90.1-2007 appendix
G.****

-Energyplus 6.0.0.023 software has been used.****

-HVAC systems has been modeled with HVAC templates in this configuration:***
*

              -Chilled Water loop with HVACTemplate:Plant:ChilledWaterLoop,
Chiller and Cooling Tower****

              -System-side equipment with HVACTemplate:System:VAV****

              -Zone-side equipment with HVACTemplate:Zone:VAV:FanPowered****

 ****

-System Fan Power modeling details:****

              -Supply Fan Total Efficiency = 0.6 ****

              -Supply Fan Delta Pressure = 1495 Pa****

              -Supply Fan Motor Efficiency = 0.9****

 ****

 ****

-Severe errors details:****

              -When Supply Fan Delta Pressure exceeds 500Pa,
simulation error log exposes unusually high amounts of recurrent severe
errors like that (over 1000 severe errors):

****

   ** Severe  ** FindRootSimpleController: Controller error for controller =
SYSTEMVAV_DATACENTER COOLING COIL CONTROLLER
   **   ~~~   **  Environment=SANTIAGO, at Simulation time=01/01 04:30 -
04:35
   **   ~~~   **   Controller function is inconsistent with user specified
controller action = Reverse action
   **   ~~~   **   Actuator will be set to maximum action
   **   ~~~   ** Controller control type=Temperature
   **   ~~~   ** Controller temperature set point = 11.41 [C]
   **   ~~~   ** Controller sensed temperature = 12.17 [C]
   **   ~~~   ** Controller actuator mass flow rate set to 0.70 [kg/s]
   **   ~~~   ** Controller actuator temperature = 12.20 [C]
   **   ~~~   **   Note: Chilled water coils should be reverse action and
the entering chilled
   **   ~~~   **         water temperature (controller actuator temperature)
should be below the setpoint temperature
   **   ~~~   **   Note: Hot water coils should be normal action and the
entering hot
   **   ~~~   **         water temperature (controller actuator temperature)
should be above the setpoint temperature****

              -Also I tried to reduce Supply Fan Total Efficiency and
maintain Supply Fan Delta Pressure less than 500Pa but severe errors also
occurred.****


Suggestions to reduce this errors or modeling system fan power in a
different way?  ****

Any comments will be appreciated....****

Regards





Alvaro Urrutia Astorga

Arquitecto.



****
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