Post on 14-Dec-2015
Lecture 19: HVAC Outside Air Systems and Modeling Guidelines
Material prepared by GARD Analytics, Inc. and University of Illinoisat Urbana-Champaign under contract to the National Renewable Energy
Laboratory. All material Copyright 2002-2003 U.S.D.O.E. - All rights reserved
2
Purpose of this Lecture
Discuss Outside Air IAQ requirements force us to draw
fresh air in from the outside environment
Outside air (OA) can have a significant impact on the building energy requirements
Show how OA is specified in EnergyPlus
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Keywords Covered in this Lecture
Air Loop Equipment ListOutside Air SystemOutside Air MixerController:Outside AirOutside Air Inlet Node ListReview of other related keywords
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Components: Special Case - Outside Air System
OUTSIDE AIR SYSTEM is a subsystem component
OA System Controller ListOA System Equipment ListOA System Availability Manager
List
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OA System Equipment List
System component type outside air mixer, coil, heat
exchanger
System component name
Repeat for each air loop component
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Air Loop Equipment List - Example
AIR LOOP EQUIPMENT LIST,
OA Sys 1 Equipment, !- Name
OUTSIDE AIR MIXER, !- KEY--System Component 1
OA Mixing Box 1; !- Component Name 1
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Outside Air System - Example
OUTSIDE AIR SYSTEM,
OA Sys 1, !- Name
OA Sys 1 Controllers, !- Name: Controller List
OA Sys 1 Equipment, !- Name of an Air Loop Equipment List
VAV Sys 1 Avail List; !- Name of a System Availability Manager List
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Outside Air Mixer
Mixed_Air_NodeOutside_Air_Stream_NodeRelief_Air_Stream_NodeReturn_Air_Stream_Node
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Outside Air Mixer - Example
OUTSIDE AIR MIXER, OA Mixing Box 1, !- Name Mixed Air Node 1, !- Mixed_Air_Node Outside Air Inlet Node 1, !- Outside_Air_Stream_Node Relief Air Outlet Node 1, !- Relief_Air_Stream_Node VAV Sys 1 Inlet Node; !- Return_Air_Stream_Node
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CONTROLLER LIST, OA Sys 1 Controllers, !- Name CONTROLLER:OUTSIDE AIR, !- Controller Type 1 OA Controller 1; !- Controller Name 1
Outside Air Mixer – Controller List
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Controller:Outside Air
Control_NodeActuated_NodeMinimum outside air flow rateMaximum outside air flow rateTemperature limitTemperature lower limit
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Controller:Outside Air - Example
CONTROLLER:OUTSIDE AIR, OA Controller 1, !- Name ECONOMIZER, !- EconomizerChoice NO RETURN AIR TEMP LIMIT, !- ReturnAirTempLimit NO RETURN AIR ENTHALPY LIMIT, !- ReturnAirEnthalpyLimit NO LOCKOUT, !- Lockout FIXED MINIMUM, !- MinimumLimit Mixed Air Node 1, !- Control_Node Outside Air Inlet Node 1, !- Actuated_Node autosize, !- min outside air flow rate {m3/s} autosize, !- max outside air flow rate {m3/s} 19., !- temperature limit {C} 4., !- temperature lower limit {C} 0.0, !- enthalpy limit {J/kg} Relief Air Outlet Node 1, !- Relief_Air_Outlet_Node VAV Sys 1 Inlet Node, !- Return_Air_Node Min OA Sched; !- Minimum Outside Air Schedule Name
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TermReheat with Outside Air Example
North
Zone
East
Zone
Resistive
Zone
Supply FanR
etu
rn A
ir M
ixe
r
Zo
ne A
ir Sp
litter
CC
VAV Box:ReHeat
VAV Box:ReHeat
Mixed OutsideAir Box
Relief Air
Outside Air
VAV Box: ReHeat
North
Zone
East
Zone
Resistive
Zone
Supply FanR
etu
rn A
ir M
ixe
r
Zo
ne A
ir Sp
litter
CC
VAV Box:ReHeat
VAV Box:ReHeat
Mixed OutsideAir Box
Relief Air
Outside Air
VAV Box: ReHeat
Air Loop contains the Mixed Air System
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TermReheat Main Branch with OA
SystemSupply Fan
CCMixed OutsideAir Box
Relief Air
Outside AirSupply Fan
CCMixed OutsideAir Box
Relief Air
Outside Air
BRANCH, Air Loop Main Branch, !- Branch Name 1.3, !- Maximum Branch Flow Rate {m3/s} OUTSIDE AIR SYSTEM, !- Comp1 Type OA Sys 1, !- Comp1 Name VAV Sys 1 Inlet Node, !- Comp1 Inlet Node Name Mixed Air Node, !- Comp1 Outlet Node Name PASSIVE, !- Comp1 Branch Control Type FAN:SIMPLE:ConstVolume, !- Comp2 Type Supply Fan 1, !- Comp2 Name Mixed Air Node, !- Comp2 Inlet Node Name< cooling coil >
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TermReheat Outside Air Node List
Mixed OutsideAir Box
Relief Air
Outside Air
Mixed OutsideAir Box
Relief Air
Outside Air
OUTSIDE AIR INLET NODE LIST,
OutsideAirInletNodes; !- 1st Node name or node list name
NODE LIST,
OutsideAirInletNodes, !- Node List Name
Outside Air Inlet Node 1; !- Node_ID_1
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TermReheat Outside Air System
Mixed OutsideAir Box
Relief Air
Outside Air
Mixed OutsideAir Box
Relief Air
Outside Air
OUTSIDE AIR SYSTEM,
OA Sys 1, !- Name
OA Sys 1 Controllers, !- Name: Controller List
OA Sys 1 Equipment, !- Name of an Air Loop Equipment List
VAV Sys 1 Avail List; !- Name of a System Availability Manager List
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TermReheat Outside Air Controller List
Mixed OutsideAir Box
Relief Air
Outside Air
Mixed OutsideAir Box
Relief Air
Outside Air
CONTROLLER LIST,
OA Sys 1 Controllers, !- Name
CONTROLLER:OUTSIDE AIR, !- Controller Type 1
OA Controller 1; !- Controller Name 1
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TermReheat Outside Air Equipment List
Mixed OutsideAir Box
Relief Air
Outside Air
Mixed OutsideAir Box
Relief Air
Outside Air
AIR LOOP EQUIPMENT LIST,
OA Sys 1 Equipment, !- Name
OUTSIDE AIR MIXER, !- KEY--System Component 1
OA Mixing Box 1; !- Component Name 1
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TermReheat Outside Air Controller
CONTROLLER:OUTSIDE AIR, OA Controller 1, !- Name ECONOMIZER, !- EconomizerChoice NO RETURN AIR TEMP LIMIT, !- ReturnAirTempLimit NO RETURN AIR ENTHALPY LIMIT, !- ReturnAirEnthalpyLimit NO LOCKOUT, !- Lockout FIXED MINIMUM, !- MinimumLimit Mixed Air Node 1, !- Control_Node Outside Air Inlet Node 1, !- Actuated_Node 0.468, !- minimum outside air flow rate {m3/s} 1.56, !- maximum outside air flow rate {m3/s} 19., !- temperature limit {C} 4., !- temperature lower limit {C} 0.0, !- enthalpy limit {J/kg} Relief Air Outlet Node 1, !- Relief_Air_Outlet_Node VAV Sys 1 Inlet Node, !- Return_Air_Node Min OA Sched; !- Minimum Outside Air Schedule Name
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TermReheat Outside Air Mixer
Mixed OutsideAir Box
Relief Air
Outside Air
Mixed OutsideAir Box
Relief Air
Outside Air
OUTSIDE AIR MIXER,
OA Mixing Box 1, !- Name
Mixed Air Node 1, !- Mixed_Air_Node
Outside Air Inlet Node 1, !- Outside_Air_Stream_Node
Relief Air Outlet Node 1, !- Relief_Air_Stream_Node
VAV Sys 1 Inlet Node; !- Return_Air_Stream_Node
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Outdoor Air Economizer
TermReheatOA.idf example file CONTROLLER:OUTSIDE AIR, OA Controller 1, !- Name ECONOMIZER, !- EconomizerChoice NO RETURN AIR TEMP LIMIT, !- ReturnAirTempLimit NO RETURN AIR ENTHALPY LIMIT, !- ReturnAirEnthalpyLimit NO LOCKOUT, !- Lockout FIXED MINIMUM, !- MinimumLimit Mixed Air Node, !- Control_Node Outside Air Inlet Node, !- Actuated_Node 0.4333, !- minimum outside air flow rate {m3/s} 1.3, !- maximum outside air flow rate {m3/s} 19., !- temperature limit {C} 4., !- temperature lower limit {C} 0.0, !- enthalpy limit {J/kg} Relief Air Outlet Node, !- Relief_Air_Outlet_Node VAV Sys 1 Inlet Node; !- Return_Air_Node
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Outdoor Air Economizer (cont’d)
Scheduled mixed air setpoint
SET POINT MANAGER:SCHEDULED, Mixed Air Temp Manager, !- Name TEMP, !- Control variable Seasonal Reset Mixed Air Temp Sch, !- Schedule Name Mixed Air Nodes; !- Name of the set point Node List NODE LIST, Mixed Air Nodes, !- Node List Name Mixed Air Node; !- Node_ID_1
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Outdoor Air Economizer (cont’d)
Mixed air setpoint adjusted for fan heat SET POINT MANAGER:SCHEDULED,
Supply Air Temp Manager 1, !- Name TEMP, !- Control variable Seasonal Reset Supply Air Temp Sch, !- Schedule Name Supply Air Temp Nodes 1; !- Name of the set point Node List
SET POINT MANAGER:MIXED AIR, Mixed Air Temp Manager 1, !- Name TEMP, !- Control variable: VAV Sys 1 Outlet Node, !- reference set point node name Main Heating Coil 1 Outlet Node, !- fan inlet node name VAV Sys 1 Outlet Node, !- fan outlet node name Mixed Air Node 1; !- Name of the set point Node or Node List
NODE LIST, Supply Air Temp Nodes 1, !- Node List Name VAV Sys 1 Outlet Node; !- Node_ID_1
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Economizer with Furnace/DX
Furnace/DX does not set a supply air setpoint
Must use setpoint managers to establish a setpoint
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Summary
Introduction of outside air into a forced air system is necessary to meet indoor air quality (IAQ) standards
Outside air (mixing box) in EnergyPlus is a component on an air loop branch
Outside air system also contains controllers that can be operated in economizer mode