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[EnergyPlus_Support] Strangely constant ventilation rates?
- To: EnergyPlus_Support@xxxxxxxxxxxxxxx
- Subject: [EnergyPlus_Support] Strangely constant ventilation rates?
- From: "thexenyth" <nick.novelli@xxxxxxxxx>
- Date: Mon, 15 Apr 2013 15:55:04 -0000
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Hello,
I'm having a hard time modifying the ventilation rates in my building. I've tried changing the "Zone Minimum Air Flow Input Method" in the the template zone VAV from "Constant" to "FixedFlowRate" and scaling the "Fixed Minimum Air Flow Rate" up from a fraction of a m3/s up through several hundred, but the ventilation rates in my main space never climb higher than maybe .25 m3/s, which accounts for ~.4ACH in my modeled space.
What could be preventing me from increasing the ventilation rates? Could it be that I have several zone working off of one air handling unit? When I change the minimum rate method, I do so for all the zones together, so that the autosizing routine doesn't get bogged down, but still, the ventilation rates are extremely constant.
For reference, sensible cooling rates needed in the building are reported to vary from 500kW to over 2500kW...so I would expect the ventilation to ramp up a bit more during the hot parts of the day/year.
Any insight appreciated!
-Nick.
!
!my HVAC templates, for reference:
HVACTemplate:Zone:VAV,
OccupiedSpace, !- Zone Name
AHU-1, !- Template VAV System Name
Thermostat_Occ, !- Template Thermostat Name
autosize, !- Supply Air Maximum Flow Rate {m3/s}
, !- Zone Heating Sizing Factor
, !- Zone Cooling Sizing Factor
Constant, !- Zone Minimum Air Flow Input Method
.01, !- Constant Minimum Air Flow Fraction !ggg changed to fixed minimum
, !- Fixed Minimum Air Flow Rate {m3/s} !ggg from ASHRAE Fundamentals lobby sizing. expect eng toolbox says 4+ACH! which is what 2.35 m3/s is.
, !- Minimum Air Flow Fraction Schedule Name
Sum, !- Outdoor Air Method
0.0025, !- Outdoor Air Flow Rate per Person {m3/s}
0.0003, !- Outdoor Air Flow Rate per Zone Floor Area {m3/s-m2}
, !- Outdoor Air Flow Rate per Zone {m3/s}
HotWater, !- Reheat Coil Type
Always_1, !- Reheat Coil Availability Schedule Name
Reverse, !- Damper Heating Action
autocalculate, !- Maximum Flow per Zone Floor Area During Reheat {m3/s-m2}
autocalculate, !- Maximum Flow Fraction During Reheat
32.2, !- Maximum Reheat Air Temperature {C}
DSOA_OFFICE, !- Design Specification Outdoor Air Object Name for Control
, !- Supply Plenum Name
, !- Return Plenum Name
None, !- Baseboard Heating Type
, !- Baseboard Heating Availability Schedule Name
autosize, !- Baseboard Heating Capacity {W}
SystemSupplyAirTemperature, !- Zone Cooling Design Supply Air Temperature Input Method
12.8, !- Zone Cooling Design Supply Air Temperature {C}
, !- Zone Cooling Design Supply Air Temperature Difference {deltaC}
SupplyAirTemperature, !- Zone Heating Design Supply Air Temperature Input Method
32.2, !- Zone Heating Design Supply Air Temperature {C}
; !- Zone Heating Design Supply Air Temperature Difference {deltaC}
! , !- Supply Plenum Name
! , !- Return Plenum Name
! SupplyAirTemperature, !- Zone Cooling Design Supply Air Temperature Input Method
HVACTemplate:Zone:VAV,
RoofZone, !- Zone Name
AHU-1, !- Template VAV System Name
Thermostat_Plenum, !- Template Thermostat Name
autosize, !- Supply Air Maximum Flow Rate {m3/s}
, !- Zone Heating Sizing Factor
, !- Zone Cooling Sizing Factor
Constant, !- Zone Minimum Air Flow Input Method
.0001, !- Constant Minimum Air Flow Fraction !ggg changed to fixed minimum
, !- Fixed Minimum Air Flow Rate {m3/s} !ggg from ASHRAE Fundamentals lobby sizing. expect eng toolbox says 4+ACH! which is what 2.35 m3/s is.
, !- Minimum Air Flow Fraction Schedule Name
Sum, !- Outdoor Air Method
0.0025, !- Outdoor Air Flow Rate per Person {m3/s}
0.0003, !- Outdoor Air Flow Rate per Zone Floor Area {m3/s-m2}
, !- Outdoor Air Flow Rate per Zone {m3/s}
HotWater, !- Reheat Coil Type
Always_1, !- Reheat Coil Availability Schedule Name
Reverse, !- Damper Heating Action
autocalculate, !- Maximum Flow per Zone Floor Area During Reheat {m3/s-m2}
autocalculate, !- Maximum Flow Fraction During Reheat
32.2, !- Maximum Reheat Air Temperature {C}
DSOA_OFFICE, !- Design Specification Outdoor Air Object Name for Control
, !- Supply Plenum Name
, !- Return Plenum Name
None, !- Baseboard Heating Type
, !- Baseboard Heating Availability Schedule Name
autosize, !- Baseboard Heating Capacity {W}
SystemSupplyAirTemperature, !- Zone Cooling Design Supply Air Temperature Input Method
12.8, !- Zone Cooling Design Supply Air Temperature {C}
, !- Zone Cooling Design Supply Air Temperature Difference {deltaC}
SupplyAirTemperature, !- Zone Heating Design Supply Air Temperature Input Method
32.2, !- Zone Heating Design Supply Air Temperature {C}
; !- Zone Heating Design Supply Air Temperature Difference {deltaC}
! SupplyAirTemperature, !- Zone Cooling Design Supply Air Temperature Input Method
HVACTemplate:Zone:VAV,
EntranceWallCavity, !- Zone Name
AHU-1, !- Template VAV System Name
Thermostat_Plenum, !- Template Thermostat Name
autosize, !- Supply Air Maximum Flow Rate {m3/s}
, !- Zone Heating Sizing Factor
, !- Zone Cooling Sizing Factor
Constant, !- Zone Minimum Air Flow Input Method
.0001, !- Constant Minimum Air Flow Fraction !ggg changed to fixed minimum
, !- Fixed Minimum Air Flow Rate {m3/s} !ggg from ASHRAE Fundamentals lobby sizing. expect eng toolbox says 4+ACH! which is what 2.35 m3/s is.
, !- Minimum Air Flow Fraction Schedule Name
Sum, !- Outdoor Air Method
0.0025, !- Outdoor Air Flow Rate per Person {m3/s}
0.0003, !- Outdoor Air Flow Rate per Zone Floor Area {m3/s-m2}
, !- Outdoor Air Flow Rate per Zone {m3/s}
HotWater, !- Reheat Coil Type
Always_1, !- Reheat Coil Availability Schedule Name
Reverse, !- Damper Heating Action
autocalculate, !- Maximum Flow per Zone Floor Area During Reheat {m3/s-m2}
autocalculate, !- Maximum Flow Fraction During Reheat
32.2, !- Maximum Reheat Air Temperature {C}
DSOA_OFFICE, !- Design Specification Outdoor Air Object Name for Control
, !- Supply Plenum Name
, !- Return Plenum Name
None, !- Baseboard Heating Type
, !- Baseboard Heating Availability Schedule Name
autosize, !- Baseboard Heating Capacity {W}
SystemSupplyAirTemperature, !- Zone Cooling Design Supply Air Temperature Input Method
12.8, !- Zone Cooling Design Supply Air Temperature {C}
, !- Zone Cooling Design Supply Air Temperature Difference {deltaC}
SupplyAirTemperature, !- Zone Heating Design Supply Air Temperature Input Method
32.2, !- Zone Heating Design Supply Air Temperature {C}
; !- Zone Heating Design Supply Air Temperature Difference {deltaC}
HVACTemplate:Zone:VAV,
RearWallCavity, !- Zone Name
AHU-1, !- Template VAV System Name
Thermostat_Plenum, !- Template Thermostat Name
autosize, !- Supply Air Maximum Flow Rate {m3/s}
, !- Zone Heating Sizing Factor
, !- Zone Cooling Sizing Factor
Constant, !- Zone Minimum Air Flow Input Method
.001, !- Constant Minimum Air Flow Fraction !ggg changed to fixed minimum
, !- Fixed Minimum Air Flow Rate {m3/s} !ggg from ASHRAE Fundamentals lobby sizing. expect eng toolbox says 4+ACH! which is what 2.35 m3/s is.
, !- Minimum Air Flow Fraction Schedule Name
Sum, !- Outdoor Air Method
0.0025, !- Outdoor Air Flow Rate per Person {m3/s}
0.0003, !- Outdoor Air Flow Rate per Zone Floor Area {m3/s-m2}
, !- Outdoor Air Flow Rate per Zone {m3/s}
HotWater, !- Reheat Coil Type
Always_1, !- Reheat Coil Availability Schedule Name
Reverse, !- Damper Heating Action
autocalculate, !- Maximum Flow per Zone Floor Area During Reheat {m3/s-m2}
autocalculate, !- Maximum Flow Fraction During Reheat
32.2, !- Maximum Reheat Air Temperature {C}
DSOA_OFFICE, !- Design Specification Outdoor Air Object Name for Control
, !- Supply Plenum Name
, !- Return Plenum Name
None, !- Baseboard Heating Type
, !- Baseboard Heating Availability Schedule Name
autosize, !- Baseboard Heating Capacity {W}
SystemSupplyAirTemperature, !- Zone Cooling Design Supply Air Temperature Input Method
12.8, !- Zone Cooling Design Supply Air Temperature {C}
, !- Zone Cooling Design Supply Air Temperature Difference {deltaC}
SupplyAirTemperature, !- Zone Heating Design Supply Air Temperature Input Method
32.2, !- Zone Heating Design Supply Air Temperature {C}
; !- Zone Heating Design Supply Air Temperature Difference {deltaC}
!- =========== ALL OBJECTS IN CLASS: HVACTEMPLATE:SYSTEM:VAV ===========
HVACTemplate:System:VAV,
AHU-1, !- Name
AHU_AS, !- System Availability Schedule Name
autosize, !- Supply Fan Maximum Flow Rate {m3/s}
autosize, !- Supply Fan Minimum Flow Rate {m3/s}
0.6, !- Supply Fan Total Efficiency
1000, !- Supply Fan Delta Pressure {Pa}
0.9, !- Supply Fan Motor Efficiency
1, !- Supply Fan Motor in Air Stream Fraction
ChilledWater, !- Cooling Coil Type
Cooling_Coil_AS, !- Cooling Coil Availability Schedule Name
, !- Cooling Coil Setpoint Schedule Name
12.8, !- Cooling Coil Design Setpoint {C}
HotWater, !- Heating Coil Type
Heating_Coil_AS, !- Heating Coil Availability Schedule Name
, !- Heating Coil Setpoint Schedule Name
12, !- Heating Coil Design Setpoint {C}
0.8, !- Gas Heating Coil Efficiency
, !- Gas Heating Coil Parasitic Electric Load {W}
None, !- Preheat Coil Type
, !- Preheat Coil Availability Schedule Name
, !- Preheat Coil Setpoint Schedule Name
7.2, !- Preheat Coil Design Setpoint {C}
0.8, !- Gas Preheat Coil Efficiency
, !- Gas Preheat Coil Parasitic Electric Load {W}
autosize, !- Maximum Outdoor Air Flow Rate {m3/s}
autosize, !- Minimum Outdoor Air Flow Rate {m3/s}
FixedMinimum, !- Minimum Outdoor Air Control Type
MinOASched, !- Minimum Outdoor Air Schedule Name
NoEconomizer, !- Economizer Type
NoLockout, !- Economizer Lockout
, !- Economizer Upper Temperature Limit {C}
, !- Economizer Lower Temperature Limit {C}
, !- Economizer Upper Enthalpy Limit {J/kg}
, !- Economizer Maximum Limit Dewpoint Temperature {C}
, !- Supply Plenum Name
, !- Return Plenum Name
DrawThrough, !- Supply Fan Placement
VariableSpeedMotorPressureReset, !- Supply Fan Part-Load Power Coefficients
CycleOnAny, !- Night Cycle Control
, !- Night Cycle Control Zone Name
None, !- Heat Recovery Type
, !- Sensible Heat Recovery Effectiveness
, !- Latent Heat Recovery Effectiveness
None, !- Cooling Coil Setpoint Reset Type
None, !- Heating Coil Setpoint Reset Type
None, !- Dehumidification Control Type
, !- Dehumidification Control Zone Name
, !- Dehumidification Setpoint {percent}
None, !- Humidifier Type
, !- Humidifier Availability Schedule Name
0, !- Humidifier Rated Capacity {m3/s}
0, !- Humidifier Rated Electric Power {W}
, !- Humidifier Control Zone Name
, !- Humidifier Setpoint {percent}
NonCoincident; !- Sizing Option
------------------------------------
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