ZoneVentilation:DesignFlowRate fluctuates
I tested with an ExampleFile VentilationSimpleTest.idf (V24-1-0). I changed the Coefficients as follows so that the ventilation rate is not affected by outdoor air temperature and velocity. I expected the ventilation rate to be constant.
ZoneVentilation:DesignFlowRate,
ZONE 1 Ventl 1, !- Name
ZONE 1, !- Zone or ZoneList or Space or SpaceList Name
Constant, !- Schedule Name
flow/zone, !- Design Flow Rate Calculation Method
6.131944, !- Design Flow Rate {m3/s}
, !- Flow Rate per Floor Area {m3/s-m2}
, !- Flow Rate per Person {m3/s-person}
, !- Air Changes per Hour {1/hr}
NATURAL, !- Ventilation Type
0, !- Fan Pressure Rise {Pa}
1, !- Fan Total Efficiency
1, !- Constant Term Coefficient
0, !- Temperature Term Coefficient
0, !- Velocity Term Coefficient
0; !- Velocity Squared Term Coefficient
I output Zone Ventilation Standard Density Volume Flow Rate, Zone Ventilation Current Density Volume Flow Rate and Zone Ventilation Mass Flow Rate, but all fluctuate. Why? What kind of ventilation rate is supposed to be constant other than current density volume, standard density volume and mass? How can I keep the ventilation rate constant?
The same bug was found in
ZoneInfiltration:DesignFlowRate.