The main elements of the PlantLoop
syntax are described in further detail below. A map of how the
input for this portion of the HVAC input fits together is
provided in the following diagram.
This alpha field must be a keyword selected from the list
of available fluids for an EnergyPlus plant loop. Either
Water, Steam or
UserDefinedFluidType may be used. If the
UserDefinedFluidType keyword is used, the following input
field i.e. User Defined Fluid Type must have a value (namely
the name of a FluidProperties:GlycolConcentration
object).
This alpha field must be specified when the previous field
is set to UserDefinedFluidType otherwise it
could be left blank. Water,
EthyleneGlycol,
PropyleneGlycol and Steam
are all “built-in” fluids for EnergyPlus (that is, all of the
appropriate properties are contained within the program). If
the fluid specified here is a mixture of water and ethylene or
propylene glycol, then only FluidProperties:GlycolConcentration
objects need to be specified and the name of the appropriate
one is used here. For another water/glycol mixture, a complete
set of fluid property data (FluidProperties:Name and
FluidProperties:Temperature objects plus multiple FluidProperties:Concentration
objects for specific heat, density, etc.) must be specified
(Ref dataset: GlycolPropertiesRefData.idf).
This alpha field is used as an identifying field for the
plant operation scheme. This field ties to the PlantEquipmentOperationSchemes
input structure, which must also be defined.
This alpha field is used to identify the node which the
Loop Manager will access the temperature setpoint that it will
try to maintain. This is typically the Plant Loop Supply Side
Outlet Node so that it will not interfere with component
temperature setpoints. An associated temperature setpoint
manager will need to be defined.
This numeric field contains the maximum loop flow rate in
cubic meters per second. This parameter is also used when the
user chooses to autocalculate the loop volume. See Volume of
the Plant Loop below and the Engineering Manual for more
details. This field is autosizable.
Volume of the plant loop in m\(^{3}\). This numeric field
contains the loop volume for the entire loop, i.e. both the
demand side and the supply side. This is used for the loop
capacitance calculation. Loop volume (m\(^{3}\)) could be calculated from
pipe size data but this is not usually known. If zero volume
is specified the loop has no fluid heat capacity. If a very
large capacitance is specified unrealistic time delay may
result and there may be poor response to changes in loop
setpoint temperature. The autocalculate
option sets the loop volume to the product of the Maximum Loop
Flow Rate and the user input for Loop Circulation Time which
defaults to 2 minutes (see below). This calculation is
described in the Engineering Reference manual.
This required alpha field contains the identifying name
given to the Plant Side Branch
List. The list referenced here should list all the branches on
the supply side of the loop.
This alpha field contains the identifying name given to the
Plant Side Connector List. The list referenced here should
list the splitter and mixer on the supply side of the
loop.
This required alpha field contains the identifying name
given to the Demand Side Branch
List. The list referenced here should list all the branches on
the demand side of the loop.
This alpha field contains the identifying name given to the
Demand Side Connector List. The list referenced here should
list the splitter and mixer on the demand side of the
loop.
The Load Distribution Scheme selects the algorithm used to
sequence equipment operation in order to meet the plant loop
demand. Currently, five schemes are functional:
Optimal operates each piece of
equipment at its optimal part load ratio. Any remaining loop
demand is distributed evenly to all of the
components.
SequentialLoad loads each piece of
equipment sequentially in the order specified in the PlantEquipmentList
to its maximum part load ratio and will operate the last
required piece of equipment between its minimum and maximum
part load ratio in order to meet the loop demand.
UniformLoad evenly distributes the
loop demand among all available components on the equipment
list for a given load range. If some components do not have
the capacity to meet the uniformly distributed load, the
remaining load is distributed sequentially to the other
available components.
SequentialUniformPLR loads all
equipment on the PlantEquipmentList
to a uniform part load ratio (PLR). Components are loaded
sequentially based on the order specified in the PlantEquipmentList
until each component is fully loaded, at which point the next
subsequent component is added and the load is distributed
uniformly based on PLR between the components.
UniformPLR will load all equipment on
the PlantEquipmentList
to a uniform part load ratio (PLR). No equipment will be
loaded below its minimum PLR. If the total load is less than
the sum of all equipment on the PlantEquipmentList
operating at their respective minimum PLRs, then the last item
in the equipment list is dropped and the load is distributed
based on a uniform PLR for the remaining plant
equipment.
Note: For all schemes, if the load for any individual
component is less than the component load at the minimum PLR,
the individual component model will false load or reduce duty
cycle while operating at the minimum part load ratio until the
load is met.
There are two choices for plant loop demand calculations
schemes in EnergyPlus: SingleSetpoint and
DualSetpointDeadband.
SingleSetpoint - For the SingleSetpoint scheme, the plant
loop is controlled to a single temperature setpoint. This
requires a setpoint manager with Control Variable =
Temperature to place a setpoint on the Loop Temperature
Setpoint Node. The setpoint will be stored in the
Node%TempSetpoint variable which may be reported using Output:Variable
"System Node Setpoint Temperature." Examples of applicable
setpoint managers include: SetpointManager:Scheduled,SetpointManager:OutdoorAirReset,SetpointManager:FollowOutdoorAirTemperature,
etc. SingleSetpoint is the default.
DualSetpoint - For the DualSetpoint scheme, the plant loop
is controlled to stay between a pair of high and low
temperature setpoints. This requires one or two setpoint
managers to place two setpoints on the Loop Temperature
Setpoint Node. The setpoints will be stored in the
Node%TempSetPointHi and Node%TempSetPointLo variables which
may be reported using Output:Variable
"System Node Setpoint High Temperature" and "System Node
Setpoint Low Temperature." There is special setpoint manager,
SetpointManager:Scheduled:DualSetpoint,
which will place both the high and low setpoints with Control
Variable = Temperature. Otherwise, two setpoint managers are
required, one with Control Variable = MaximumTemperature and
another with Control Variable = MinimumTemperature. The two
setpoint managers may be the same kind or different, but care
should be taken so that the MinimumTemperature is not set
higher than the MaximumTemperature. Examples of applicable
setpoint managers include: SetpointManager:Scheduled,SetpointManager:OutdoorAirReset,SetpointManager:FollowOutdoorAirTemperature,
etc. Note that DualSetpoint is used only for plant loops with
both heating and cooling supply equipment, such as a water
loop heat pump system. When the loop temperature rises above
the MaximumTemperature setpoint, then the loop will request
cooling, and when the loop temperature is below the
MinimumTemperature setpoint it will request heating.
DualSetpoint cannot be used to control a single-mode loop,
such as a hot water heating loop between operating between
high and low boiler setpoints.
The plant loop demand calculation scheme determines the
amount of heating or cooling necessary to bring the
temperature of the Plant Loop to its setpoint(s). When this
value is determined then the load distribution scheme
explained in the previous section takes this value and
distributes the load to the appropriate equipment. The demand
calculation scheme determines how the load is calculated. See
more information in the Engineering Document.
This field specifies a primary-secondary plant loop
simulation. When a common pipe option is specified, the plant
side of the loop is the primary loop and the demand side of
the loop is the secondary loop, and a pump object must be
placed on the demand side inlet branch. The three options are
“None”, “CommonPipe” and
“TwoWayCommonPipe”. “None”
means that there is no secondary loop and the plant loop is
modeled as a single primary loop.
“CommonPipe” means that the common pipe
interface does not attempt any temperature control, it only
satisfies secondary (demand side) flow requests.
“TwoWayCommonPipe” allows control of the
secondary (demand side) inlet temperature or the primary
(plant side) inlet temperature by placing a setpoint on the
corresponding node. If this field is left blank, it will
default to “None”. If the field is set to “None” and the
program finds a pump on the demand side it will result in a
fatal error. If the field is set to “CommonPipe” or
“TwoWayCommonPipe” and the program does not find a pump on the
demand side it will result in a fatal error. The common pipe
simulation is currently limited to simulating loop pumps,
i.e. each pump should be placed on the inlet branch of the
plant side or demand side of the loop.
This field lets user to choose if this plant loop will be
involved in a pressure drop calculation. This requires that
at least one branch on the loop have pressure drop data. If
not, an error will be thrown due to the input mismatch.
Currently there are two pressure drop simulation types:
“PumpPowerCorrection” and “LoopFlowCorrection”. In both of
these methods, branch pressure drop data is used to calculate
a dynamic loop pressure drop and is used to update pumping
power accordingly. The flow correction method allows the user
to enter information regarding the pressure curve of a
constant speed pump so that the simulation can dynamically
resolve the pressure vs. flow relationship in the plant loop.
This is limited to constant speed pumps, as the variable speed
pumps are expected to resolve as if it were controlled by a
variable drive, so that they can inherently meet any pressure
and flow demand required by the loop. This is also limited to
“loop pumps”, where there is a single pump on the plant loop.
Common pipe simulations and “branch pump” simulations are not
compatible with this level of pressure simulation. See the
documentation for the Pump:ConstantSpeed
in order to determine required inputs for this pressure
simulation method to be performed. In the pressure drop
system, parallel flow rates are not resolved (to match the
pressure drop for the parallel system). Enhancements to this
calculation are planned which will allow parallel branch flow
resolution. See the Engineering Reference document for more
information on how this works.
This field specifies the time it takes the fluid to
circulate through the entire loop. It is only used when Plant
Loop Volume is set to autocalculate. The default is 2
minutes.
An example of this statement used in an IDF is:
PlantLoop,
Hot Water Loop, !- Plant Loop Name
Water, !- Fluid Type
, !- User Defined Fluid Type
Hot Loop Operation, !- Plant Operation Scheme List Name
HW Loop Outlet Node, !- Loop Temperature Setpoint Schedule Name
100, !- Maximum Loop Temperature {C}
10, !- Minimum Loop Temperature {C}
autosize, !- Maximum Loop Volumetric Flow Rate {m3/s}
0.0, !- Minimum Loop Volumetric Flow Rate {m3/s}
autosize, !- volume of the plant loop {m3}
HW Supply Inlet Node, !- Plant Side Inlet Node Name
HW Supply Outlet Node, !- Plant Side Outlet Node Name
Heating Supply Side Branches, !- Plant Side Branch List Name
Heating Supply Side Connectors, !- Plant Side Connector List Name
HW Demand Inlet Node, !- Demand Side Inlet Node Name
HW Demand Outlet Node, !- Demand Side Outlet Nodes Name
Heating Demand Side Branches, !- Demand Side Branch List Name
Heating Demand Side Connectors, !- Demand Side Connector List Name
Optimal; !- Load Distribution Scheme
In the above example input there is no system availability
manager specified and the Demand Calculation Scheme will
default to SingleSetpoint using a single setpoint manager.
Common pipe simulation field in the above example will default
to “NONE” since it is not specified.
In the following output variables, “Debug” denotes
variables that are used primarily by the developers and whose
names and application may be cryptic to users. .
HVAC,Average,Plant Supply Side Cooling Demand Rate
[W]
HVAC,Average,Plant Supply Side Heating Demand Rate
[W]
HVAC,Average,Plant Supply Side Inlet Mass Flow Rate
[kg/s]
HVAC,Average,Plant Supply Side Inlet Temperature
[C]
HVAC,Average,Plant Supply Side Outlet Temperature
[C]
HVAC,Average,Plant Supply Side Not Distributed Demand
Rate [W]
HVAC,Average,Plant Supply Side Unmet Demand Rate
[W]
HVAC,Sum,Plant Solver Sub Iteration Count []
HVAC,Sum,Plant Solver Half Loop Calls Count []
HVAC,Average,Debug Plant Loop Bypass Fraction
HVAC,Average,Debug Plant Last Simulated Loop Side
[-]
HVAC,Average,Plant Common Pipe Mass Flow Rate
[Kg/s]
HVAC,Average,Plant Common Pipe Temperature [C]
HVAC,Average,Plant Common Pipe Flow Direction Status
[]
HVAC,Average,Plant Common Pipe Primary Mass Flow Rate
[Kg/s]
HVAC,Average,Plant Common Pipe Secondary Mass Flow Rate
[Kg/s]
HVAC,Average,Primary Side Common Pipe Flow Direction
[]
HVAC,Average,Secondary Side Common Pipe Flow Direction
[]
HVAC,Average,Plant Common Pipe Primary to Secondary
Mass Flow Rate [Kg/s]
HVAC,Average,Plant Common Pipe Secondary to Primary
Mass Flow Rate [Kg/s]
HVAC,Average,Plant System Cycle On Off Status
[]
HVAC,Average,Plant Demand Side Loop Pressure Difference
[Pa]
HVAC,Average,Plant Supply Side Loop Pressure Difference
[Pa]
This is the value of the net demand required to meet the
cooling setpoint of the loop. If the loop setpoint is met for
the current HVAC timestep, Plant Supply Side Cooling Demand
Rate will equal sum of the total cooling demand from the
demand side coils on the loop. It will also equal the cooling
output of all chillers (or other cooling equipment) on the
loop less any pump heat added to the fluid. For example, for
a chilled water loop with one chiller and one pump serving one
chilled water coil: Plant Supply Side Cooling Demand Rate
will equal the chiller evaporator heat transfer less the pump
heat to fluid, and it will also equal the chilled water coil
total cooling output.
If the plant loop setpoint is not met, Plant Supply Side
Cooling Demand Rate will equal the sum of the total cooling
demand from the demand side coils on the loop plus the
additional cooling required to bring the loop flow to
setpoint. If the loop remains off setpoint for successive
timesteps, the demand required to return to setpoint will
repeat in each timestep until the loop reaches setpoint. For
this reason, Plant Supply Side Cooling Demand Rate should not
be summed over time, because it will overstate the demand
whenever the loop is off setpoint.
This is the value of the net demand required to meet the
heating setpoint of the loop. If the loop setpoint is met for
the current HVAC timestep, Plant Supply Side Heating Demand
Rate will equal sum of the total heating demand from the
demand side coils on the loop. It will also equal the heating
output of all boilers (or other cooling equipment) on the loop
plus any pump heat added to the fluid. For example, for a hot
water loop with one boiler and one pump serving one hot water
coil: Plant Supply Side Heating Demand Rate will equal the
boiler heat transfer plus the pump heat to fluid, and it will
also equal the hot water coil total heating output.
If the plant loop setpoint is not met, Plant Supply Side
Heating Demand Rate will equal the sum of the total heating
demand from the demand side coils on the loop plus the
additional heating required to bring the loop flow to
setpoint. If the loop remains off setpoint for successive
timesteps, the demand required to return to setpoint will
repeat in each timestep until the loop reaches setpoint. For
this reason, Plant Supply Side Heating Demand Rate should not
be summed over time, because it will overstate the demand
whenever the loop is off setpoint.
Plant
Supply Side Inlet Mass Flow Rate [kg/s][LINK]
This is the value of the mass flow rate at the Inlet to
Plant Loop on the supply side. There is not an associated
Plant Loop outlet node flow rate since continuity must be
maintained in the loop and the outlet must be the same.
This is the value of the temperature at the outlet to the
plant loop on the supply side.
Plant
Supply Side Not Distributed Demand Rate [W][LINK]
This is the value of the demand that could not be
distributed to the plant equipment because of some constraint
in the plant operation scheme. This is a record of the loop
operation scheme supervisory controls after attempting to
distribute the load. For example it would be non-zero in
situations where the load is larger than the upper limit of
capacities set for the plant equipment controls. This output
is for before the equipment has actually been
simulated whereas the separate output Plant Supply Side Unmet
Demand Rate is for after the equipment has
simulated.
This is the value of the demand NOT provided by the plant
equipment to meet the heating or cooling setpoint of the loop.
The value is positive when the plant equipment cannot meet the
setpoint, and the value is negative when the plant equipment
provides more than enough heating or cooling to meet the
setpoint. A negative value can happen when the amount of
demand is smaller than the minimum capacity of the equipment
using the minimum part load ratio.
This is the count of iterations that the overall plant
simulation used over the period of time being reported. This
high-level output is from the plant solver used for all the
plant loops and condenser loops in the model.
This is the count of calls to model individual half-loops
that occurred during the overall plant simulation over the
period of time being reported. This includes all the
half-loops for both plant loops and condenser loops.
This output gives the direction of flow in common pipe. The
value is an integer and can be 0, 1 or 2. Since the output
value is averaged over reporting interval, a non-integer value
may be shown as an output when the reporting interval is not
detailed. An output value of 0 means that there was no flow in
common pipe. An output value of 1 means that the secondary
flow is greater than primary flow, whereas a value of 2 means
that primary flow is greater than secondary flow.
Plant
Common Pipe Primary Mass Flow Rate [Kg/s][LINK]
This output variable gives the mass flow in the primary
side common pipe leg in a Two-Way common pipe simulation.
Value is averaged over the reporting interval.
Plant
Common Pipe Secondary Mass Flow Rate [Kg/s][LINK]
This output variable gives the mass flow in the secondary
side common pipe leg in a Two-Way common pipe simulation.
Value is averaged over the reporting interval.
This output variable gives the direction of flow in a
primary side common pipe leg in a Two-Way Common Pipe
Simulation. A value of zero means there was no flow in the
pipe. A value of 1 means the flow was from top to bottom in
EnergyPlus loop schematic. So for primary side, a value of 1
means the flow is from Primary side inlet to Primary side
outlet and a value of 2 means flow is from Primary side outlet
to Primary side inlet.
Secondary
Side Common Pipe Flow Direction [][LINK]
This output variable gives the direction of flow in a
Secondary side common pipe leg in a Two-Way Common Pipe
Simulation. A value of zero means there was no flow in the
pipe. A value of 1 means the flow was from top to bottom in
EnergyPlus loop schematic. So for Secondary side, a value of 1
means the flow is from Secondary side outlet to Secondary side
inlet and a value of 2 means flow is from Secondary side inlet
to Secondary side outlet. Note that this is opposite to the
primary side common pipe.
Plant
Common Pipe Primary to Secondary Mass Flow Rate [Kg/s][LINK]
This output variable gives the mass flow from primary to
secondary side in a Two-Way common pipe simulation. Value is
averaged over the reporting interval.
Plant
Common Pipe Secondary to Primary Mass Flow Rate [Kg/s][LINK]
This output variable gives the mass flow from secondary to
primary side in a Two-Way common pipe simulation. Value is
averaged over the reporting interval.
This field is the availability status of a Plant Loop. This
status flag is a result of the calculations made by the System
Availability Manager(s) listed in a System Availability
Manager List. When a single availability manager is used in a
System Availability Manager List, this is also the
availability status reported by the specific availability
manager (Ref. System Availability Manager Outputs). When
multiple availability managers are used in a System
Availability Manager List, the loop availability status is
determine by the rules associated with Plant Loops (see rules
described for Group – System Availability Managers). The
control status outputs are represented using integers 0
through 2.. These integers represent NoAction (0),
ForceOff (1), and CycleOn (2). Since the
status output is averaged, the output result may not
correspond to the values described here when output variable
frequencies other than detailed are used. Use the “detailed”
reporting frequency (Ref. Output:Variable
object) to view the availability status at each simulation
timestep.
Plant
Demand Side Loop Pressure Difference [Pa][LINK]
This field allows the user to output the demand side
pressure drop of a plant loop. This output is only recognized
if a valid pressure simulation is being performed. To do
this, the user must specify a pressure simulation type as an
input in the PlantLoop
object, and input at least one pressure drop curve on a branch
of the plant loop. This particular output is only relevant if
the user puts that curve on the demand side of the loop.
Plant
Supply Side Loop Pressure Difference [Pa][LINK]
This field allows the user to output the supply side
pressure drop of a plant loop. This output is only recognized
if a valid pressure simulation is being performed. To do
this, the user must specify a pressure simulation type as an
input in the PlantLoop
object, and input at least one pressure drop curve on a branch
of the plant loop. This particular output is only relevant if
the user puts that curve on the supply side of the loop.
This output is the total pressure drop of a plant loop.
This output is only recognized if a valid pressure simulation
is being performed. To do this, the user must specify a
pressure simulation type as an input in the PlantLoop
object, and input at least one pressure drop curve on a branch
of the plant loop. This particular output is relevant
regardless of the location of pressure drop curves: demand
side, supply side, or both.
The following advanced output variables are also available
for plant loops (and condenser loops) when advanced output
variables are requested (e.g. “Output:Diagnostics,
DisplayAdvancedReportVariable;”).
HVAC,Average,Plant Demand Side Lumped Capacitance
Temperature [C]
HVAC,Average,Plant Supply Side Lumped Capacitance
Temperature [C]
HVAC,Average,Plant Demand Side Lumped Capacitance Heat
Transport Rate [W]
HVAC,Average,Plant Supply Side Lumped Capacitance Heat
Transport Rate [W]
HVAC,Average,Plant Demand Side Lumped Capacitance Heat
Storage Rate [W]
HVAC,Average,Plant Supply Side Lumped Capacitance Heat
Storage Rate [W]
HVAC,Sum,Plant Demand Side Lumped Capacitance Excessive
Storage Time [hr]
HVAC,Sum,Plant Supply Side Lumped Capacitance Excessive
Storage Time [hrW]
Plant
Demand Side Lumped Capacitance Temperature [C][LINK]
Plant
Supply Side Lumped Capacitance Temperature [C][LINK]
These two outputs are the temperature of the plant (or
condenser) loop’s working fluid where the two half-loops
interface together. The program models heat capacitance in
the volume of fluid inside the plant loop itself using two
simple models for “well-stirred” tanks located at each of the
half-loop inlet and outlet pairs. These tank models also
receive the heat transferred to the fluid by the work done by
pumping and resulting friction heating. One output is for the
point where the fluid leaves the supply side and enters the
demand side. The other output is for the point where the
fluid leaves the demand side and enters the supply side.
Plant
Demand Side Lumped Capacitance Heat Transport Rate [C][LINK]
Plant
Supply Side Lumped Capacitance Heat Transport Rate [C][LINK]
These two outputs are the heat transfer rate to the the
plant (or condenser) loop’s working fluid in the two
half-loops. The program models heat capacitance in the volume
of fluid inside the plant loop itself using two simple models
for well-stirred tanks located at each of the
half-loop inlet and outlet pairs. These tank models also
receive the heat transferred to the fluid by the work done by
pumping and resulting friction heating. One output is for the
point where the fluid leaves the supply side and enters the
demand side. The other output is for the point where the
fluid leaves the demand side and enters the supply side.
Plant
Demand Side Lumped Capacitance Heat Storage Rate [C][LINK]
Plant
Supply Side Lumped Capacitance Heat Storage Rate [C][LINK]
These two outputs are the heat storage rate of the plant
(or condenser) loop’s working fluid in the two half-loops.
The program models heat capacitance in the volume of fluid
inside the plant loop itself using two simple models for
well-stirred tanks located at each of the half-loop
inlet and outlet pairs. These tank models also receive the
heat transferred to the fluid by the work done by pumping and
resulting friction heating. One output is for the point where
the fluid leaves the supply side and enters the demand side.
The other output is for the point where the fluid leaves the
demand side and enters the supply side.
Plant
Demand Side Lumped Capacitance Excessive Storage Time [C][LINK]
Plant
Supply Side Lumped Capacitance Excessive Storage Time [C][LINK]
These two outputs are the excess storage time of the plant
(or condenser) loop’s working fluid in the two half-loops.
The excess storage time is determined by adding the time when
the heat storage rate exceeds the heat transfer rate into the
two half-loops at each time step. The program models heat
capacitance in the volume of fluid inside the plant loop
itself using two simple models for well-stirred tanks
located at each of the half-loop inlet and outlet pairs.
These tank models also receive the heat transferred to the
fluid by the work done by pumping and resulting friction
heating. One output is for the point where the fluid leaves
the supply side and enters the demand side. The other output
is for the point where the fluid leaves the demand side and
enters the supply side.
This output is available for every component on every
branch in a plant (or condenser) loop and shows the outcome of
the load dispatch performed by the operation schemes. This
the load in watts passed from the supervisor routines to the
equipment component models. This provides a record of what a
particular component was asked to do by the supervisory
routines. This can be useful for diagnosing issues in
operation schemes when a component or loop is failing to meet
the load.
The condenser loop input is very similar to that for the
plant loop. As of version 7, the two loops are modeled the
same way and inside the program all condenser loops are just
plant loops. (In future versions of the program, this CondenserLoop
object might be deprecated and these loops will be described
using the PlantLoop
object.) The main differences are the applicable components
and operation schemes. This is depicted in the following
diagram.
This alpha field must be a keyword selected from the list
of available fluids for an EnergyPlus plant loop. Either
Water or
UserDefinedFluidType may be used. If the
UserDefinedFluidType keyword is used, the following input
field i.e. User Defined Fluid Type must have a value (namely
the name of a FluidProperties:GlycolConcentration
object).
This alpha field must be specified when the previous field
is set to UserDefinedFluidType otherwise it
could be left blank. Water,
EthyleneGlycol, and
PropyleneGlycol are all “built-in” fluids for
EnergyPlus (that is, all of the appropriate properties are
contained within the program). If the fluid specified here is
a mixture of water and ethylene or propylene glycol, then only
FluidProperties:GlycolConcentration
objects need to be specified and the name of the appropriate
one is used here. For another water/glycol mixture, a complete
set of fluid property data (FluidProperties:Name and
FluidProperties:Temperature objects plus multiple FluidProperties:Concentration
objects for specific heat, density, etc.) must be specified
(Ref dataset: GlycolPropertiesRefData.idf).
This alpha field is used as an identifying field for the
condenser operation scheme. This field ties to the Condenser
Operation Schemes input structure, which must also be
defined.
Field:
Condenser Loop Temperature Setpoint Node Name[LINK]
This alpha field is used to identify the node which the
Loop Manager will access the temperature setpoint that it will
try to maintain. This is typically the Condenser Loop Supply
Side Outlet Node so that it will not interfere with component
temperature setpoints. An associated temperature setpoint
manager will need to be defined.
This numeric field contains the minimum allowable
temperature in Celsius for this loop. This minimum loop
temperature is used by the cooling towers to make sure that
the minimum is not violated to keep the equipment safe. The
minimum is also used to trigger the minimum temperature
warning and will notify the user if it gets too low.
Volume of the condenser loop in m\(^{3}\). This numeric field
contains the loop volume for the entire loop, i.e., both the
demand side and the supply side. This is used for the loop
capacitance calculation. Loop volume (m\(^{3}\)) could be calculated from
pipe size data but this is not usually known. If zero volume
is specified the loop has no fluid heat capacity. If a very
large capacitance is specified unrealistic time delay may
result and there may be poor response to changes in loop
setpoint temperature. The autocalculate
option sets the loop volume to the product of the Maximum Loop
Flow Rate and the user input for Loop Circulation Time which
defaults to 2 minutes (see below). This calculation is
described in the Engineering Reference manual.
This required alpha field contains the identifying name
given to the Condenser Side Outlet Node. This node is the
outlet of the supply side of the loop.
This required alpha field contains the identifying name
given to the Condenser Side Branch
List. The list referenced here should list all the branches on
the supply side of the loop.
This required alpha field contains the identifying name
given to the Condenser Side Connector List. The list
referenced here should list the splitter and mixer on the
supply side of the loop.
This required alpha field contains the identifying name
given to the Demand Side Outlet Node. This node is the outlet
of the demand side of the loop.
Field:
Condenser Demand Side Branch List Name[LINK]
This required alpha field contains the identifying name
given to the Demand Side Branch
List. The list referenced here should list all the branches
on the demand side of the loop.
Field:
Condenser Demand Side Connector List Name[LINK]
This required alpha field contains the identifying name
given to the Demand Side Connector List. The list referenced
here should list the splitter and mixer on the demand side of
the loop.
This alpha field contains the Load Distribution Scheme
Keyword. The Load Distribution Scheme selects the algorithm
used to sequence equipment operation in order to meet the
plant loop demand. Currently, five schemes are functional.
Optimal operates each piece of equipment at
its optimal part load ratio and will operate the last
component between its minimum and maximum part load ratio in
order to meet the loop demand. SequentialLoad
loads each piece of equipment sequentially in the order
specified in the PlantEquipmentList
to its maximum part load ratio and will operate the last
required piece of equipment between its minimum and maximum
part load ratio in order to meet the loop demand.
UniformLoad evenly distributes the loop
demand among all available components on the equipment list
for a given load range. SequentialUniformPLR
loads all equipment on the PlantEquipmentList
to a uniform part load ratio (PLR). Components are loaded
sequentially based on the order specified in the PlantEquipmentList
until each component is fully loaded, at which point the next
subsequent component is added and the load is distributed
uniformly based on PLR between the components.
UniformPLR will load all equipment on the PlantEquipmentList
to a uniform part load ratio (PLR). No equipment will be
loaded below its minimum PLR. If the total load is less than
the sum of all equipment on the PlantEquipmentList
operating at their respective minimum PLRs, then the last item
in the equipment list is dropped and the load is distributed
based on a uniform PLR for the remaining plant equipment.
Note: For all schemes, if the load for any individual
component is less than the component load at the minimum PLR,
the individual component model will false load or reduce duty
cycle while operating at the minimum part load ratio until the
load is met.
This field lets user to choose if this plant loop will be
involved in a pressure drop calculation. This requires that
at least one branch on the loop have pressure drop data. If
not, an error will be thrown due to the input mismatch.
Currently there are two pressure drop simulation types:
“PumpPowerCorrection” and “LoopFlowCorrection”. In both of
these methods, branch pressure drop data is used to calculate
a dynamic loop pressure drop and is used to update pumping
power accordingly. The flow correction method allows the user
to enter information regarding the pressure curve of a
constant speed pump so that the simulation can dynamically
resolve the pressure vs. flow relationship in the plant loop.
This is limited to constant speed pumps, as the variable speed
pumps are expected to resolve as if it were controlled by a
variable drive, so that they can inherently meet any pressure
and flow demand required by the loop. This is also limited to
“loop pumps”, where there is a single pump on the plant loop.
Common pipe simulations and “branch pump” simulations are not
compatible with this level of pressure simulation. See the
documentation for the Pump:ConstantSpeed
in order to determine required inputs for this pressure
simulation method to be performed. In the pressure drop
system, parallel flow rates are not resolved (to match the
pressure drop for the parallel system). Enhancements to this
calculation are planned which will allow parallel branch flow
resolution. See the Engineering Reference document for more
information on how this works.
This field specifies the time it takes the fluid to
circulate through the entire loop. It is only used when
Condenser Loop Volume is set to autocalculate. The default is
2 minutes.
An example of this statement used in an IDF is:
CondenserLoop,
Condenser Water Loop, !- Name
Water, !- Fluid Type
, !- User Defined Fluid Type
Tower Loop Operation, !- Condenser Equipment Operation Scheme Name
Condenser Supply Outlet Node, !- Condenser Loop Temperature Setpoint Node Name
80, !- Maximum Loop Temperature {C}
10, !- Minimum Loop Temperature {C}
autosize, !- Maximum Loop Flow Rate {m3/s}
0.0, !- Minimum Loop Flow Rate {m3/s}
autocalculate, !- Condenser Loop Volume {m3}
Condenser Supply Inlet Node,!- Condenser Side Inlet Node Name
Condenser Supply Outlet Node, !- Condenser Side Outlet Node Name
Condenser Supply Side Branches, !- Condenser Side Branch List Name
Condenser Supply Side Connectors, !- Condenser Side Connector List Name
Condenser Demand Inlet Node,!- Demand Side Inlet Node Name
Condenser Demand Outlet Node, !- Demand Side Outlet Node Name
Condenser Demand Side Branches, !- Condenser Demand Side Branch List Name
Condenser Demand Side Connectors, !- Condenser Demand Side Connector List Name
SequentialLoad; !- Load Distribution Scheme
SetpointManager:FollowOutdoorAirTemperature,
MyCondenserControl, !- Name
Temperature, !- Control Variable
OutdoorAirWetBulb, !- Reference Temperature Type
0, !- Offset Temperature Difference {deltaC}
80, !- Maximum Setpoint Temperature {C}
10, !- Minimum Setpoint Temperature {C}
Condenser Supply Outlet Node; !- Setpoint Node or NodeList Name
CondenserLoop,
Chilled Water Condenser Loop, !- Name
UserDefinedFluidType, !- Fluid Type
PropyleneGlycol15Percent, !- User Defined Fluid Type
Tower Loop Operation, !- Condenser Equipment Operation Scheme Name
Condenser Supply Outlet Node, !- Condenser Loop Temperature Setpoint Node Name
80, !- Maximum Loop Temperature {C}
10, !- Minimum Loop Temperature {C}
0.00330000, !- Maximum Loop Flow Rate {m3/s}
0, !- Minimum Loop Flow Rate {m3/s}
autocalculate, !- Condenser Loop Volume {m3}
Condenser Supply Inlet Node,!- Condenser Side Inlet Node Name
Condenser Supply Outlet Node, !- Condenser Side Outlet Node Name
Condenser Supply Side Branches, !- Condenser Side Branch List Name
Condenser Supply Side Connectors, !- Condenser Side Connector List Name
Condenser Demand Inlet Node,!- Demand Side Inlet Node Name
Condenser Demand Outlet Node, !- Demand Side Outlet Node Name
Condenser Demand Side Branches, !- Condenser Demand Side Branch List Name
Condenser Demand Side Connectors, !- Condenser Demand Side Connector List Name
SequentialLoad; !- Load Distribution Scheme
This is the value of the net demand required to meet the
cooling setpoint of the loop. If the loop setpoint is met for
the current HVAC timestep, Plant Supply Side Cooling Demand
Rate will equal sum of the total cooling demand from the
demand side components on the loop (typically condenser coils
of chillers, etc.). It will also equal the cooling output of
all condensing equipment such as cooling towers on the loop
less any pump heat added to the fluid. For example, for a
condenser loop with one tower and one pump serving one
chiller, Plant Supply Side Cooling Demand Rate will equal the
tower water-side heat transfer less the pump heat to fluid,
and it will also equal the chiller condenser heat transfer
rate.
If the condenser loop setpoint is not met, Plant Supply
Side Cooling Demand Rate will equal the sum of the total
cooling demand from the demand side components on the loop
plus the additional cooling required to bring the loop flow to
setpoint. If the loop remains off setpoint for successive
timesteps, the demand required to return to setpoint will
repeat in each timestep until the loop reaches setpoint. For
this reason, Plant Supply Side Cooling Demand Rate should not
be summed over time, because it will overstate the demand
whenever the loop is off setpoint.
This is the value of the net demand required to meet the
heating setpoint of the loop. If the loop setpoint is met for
the current HVAC timestep, Plant Supply Side Heating Demand
Rate will equal sum of the total heating demand from the
demand side components on the loop. It will also equal the
heating output of all heating equipment on the supply side of
the loop plus any pump heat added to the fluid. For example,
for a condenser loop with one ground loop heat exchanger and
one pump serving one water-to-water heat pump, Plant Supply
Side Heating Demand Rate will equal the ground loop heat
transfer plus the pump heat to fluid, and it will also equal
the heat pump condenser side heat transfer rate.
If the condenser loop setpoint is not met, Plant Supply
Side Heating Demand Rate will equal the sum of the total
heating demand from the demand side components on the loop
plus the additional heating required to bring the loop flow to
setpoint. If the loop remains off setpoint for successive
timesteps, the demand required to return to setpoint will
repeat in each timestep until the loop reaches setpoint. For
this reason, Plant Supply Side Heating Demand Rate should not
be summed over time, because it will overstate the demand
whenever the loop is off setpoint.
Plant
Supply Side Inlet Mass Flow Rate [kg/s][LINK]
This is the value of the mass flow rate at the Inlet to
Condenser Loop on the supply side. There is not an associated
Condenser Loop outlet node flow rate since continuity must be
maintained in the loop and the outlet must be the same.
This is the value of the demand that could not be
distributed to the condenser equipment because of some
constraint in the operation scheme. This is a record of the
loop operation scheme supervisory controls after attempting to
distribute the load. For example it would be non-zero in
situations where the load is larger than the upper limit of
capacities set for the condenser equipment controls. This
output is for before the equipment has actually been
simulated whereas the separate output Plant Supply Side Unmet
Demand Rate is for after the equipment has
simulated.
This is the value of the demand NOT provided by the
condenser equipment to meet the heating or cooling setpoint of
the loop. The value is positive when the condenser equipment
cannot meet the setpoint, and the value is negative when the
condenser equipment provides more than enough heating or
cooling to meet the setpoint. A negative value can happen when
the amount of demand is smaller than the minimum capacity of
the equipment using the minimum part load ratio.
Plant
Demand Side Loop Pressure Difference [Pa][LINK]
This field is the demand side pressure drop of a condenser
loop. This output is only recognized if a valid pressure
simulation is being performed. To do this, the user must
specify a pressure simulation type as an input in the CondenserLoop
object, and input at least one pressure drop curve on a branch
of the plant/condenser loop. This particular output is only
relevant if the user puts that curve on the demand side of the
loop.
Plant
Supply Side Loop Pressure Difference [Pa][LINK]
This field is the supply side pressure drop of a condenser
loop. This output is only recognized if a valid pressure
simulation is being performed. To do this, the user must
specify a pressure simulation type as an input in the CondenserLoop
object, and input at least one pressure drop curve on a branch
of the plant/condenser loop. This particular output is only
relevant if the user puts that curve on the supply side of the
loop.
This field is the total pressure drop of a condenser loop.
This output is only recognized if a valid pressure simulation
is being performed. To do this, the user must specify a
pressure simulation type as an input in the CondenserLoop
object, and input at least one pressure drop curve on a branch
of the plant/condenser loop. This particular output is
relevant regardless of the location of pressure drop curves:
demand side, supply side, or both.
Group – Plant-Condenser Loops[LINK]
PlantLoop[LINK]
The main elements of the PlantLoop syntax are described in further detail below. A map of how the input for this portion of the HVAC input fits together is provided in the following diagram.
Inputs[LINK]
Field: Name[LINK]
This alpha field is used as an identifying field for the plant loop.
Field: Fluid Type[LINK]
This alpha field must be a keyword selected from the list of available fluids for an EnergyPlus plant loop. Either Water, Steam or UserDefinedFluidType may be used. If the UserDefinedFluidType keyword is used, the following input field i.e. User Defined Fluid Type must have a value (namely the name of a FluidProperties:GlycolConcentration object).
Field: User Defined Fluid Type[LINK]
This alpha field must be specified when the previous field is set to UserDefinedFluidType otherwise it could be left blank. Water, EthyleneGlycol, PropyleneGlycol and Steam are all “built-in” fluids for EnergyPlus (that is, all of the appropriate properties are contained within the program). If the fluid specified here is a mixture of water and ethylene or propylene glycol, then only FluidProperties:GlycolConcentration objects need to be specified and the name of the appropriate one is used here. For another water/glycol mixture, a complete set of fluid property data (FluidProperties:Name and FluidProperties:Temperature objects plus multiple FluidProperties:Concentration objects for specific heat, density, etc.) must be specified (Ref dataset: GlycolPropertiesRefData.idf).
Field: Plant Equipment Operation Scheme Name[LINK]
This alpha field is used as an identifying field for the plant operation scheme. This field ties to the PlantEquipmentOperationSchemes input structure, which must also be defined.
Field: Loop Temperature Setpoint Node Name[LINK]
This alpha field is used to identify the node which the Loop Manager will access the temperature setpoint that it will try to maintain. This is typically the Plant Loop Supply Side Outlet Node so that it will not interfere with component temperature setpoints. An associated temperature setpoint manager will need to be defined.
Field: Maximum Loop Temperature[LINK]
This numeric field contains the maximum allowable temperature in Celsius for this loop.
Field: Minimum Loop Temperature[LINK]
This numeric field contains the minimum allowable temperature in Celsius for this loop.
Field: Maximum Loop Flow Rate[LINK]
This numeric field contains the maximum loop flow rate in cubic meters per second. This parameter is also used when the user chooses to autocalculate the loop volume. See Volume of the Plant Loop below and the Engineering Manual for more details. This field is autosizable.
Field: Minimum Loop Flow Rate[LINK]
This numeric field contains the minimum loop flow rate in cubic meters per second.
Field: Plant Loop Volume[LINK]
Volume of the plant loop in m\(^{3}\). This numeric field contains the loop volume for the entire loop, i.e. both the demand side and the supply side. This is used for the loop capacitance calculation. Loop volume (m\(^{3}\)) could be calculated from pipe size data but this is not usually known. If zero volume is specified the loop has no fluid heat capacity. If a very large capacitance is specified unrealistic time delay may result and there may be poor response to changes in loop setpoint temperature. The autocalculate option sets the loop volume to the product of the Maximum Loop Flow Rate and the user input for Loop Circulation Time which defaults to 2 minutes (see below). This calculation is described in the Engineering Reference manual.
Field: Plant Side Inlet Node Name[LINK]
This required alpha field contains the identifying name given to the Plant Side Inlet Node. This node is the inlet to the supply side of the loop.
Field: Plant Side Outlet Node Name[LINK]
This required alpha field contains the identifying name given to the Plant Side Outlet Node. This node is the outlet of the supply side of the loop.
Field: Plant Side Branch List Name[LINK]
This required alpha field contains the identifying name given to the Plant Side Branch List. The list referenced here should list all the branches on the supply side of the loop.
Field: Plant Side Connector List Name[LINK]
This alpha field contains the identifying name given to the Plant Side Connector List. The list referenced here should list the splitter and mixer on the supply side of the loop.
Field: Demand Side Inlet Node Name[LINK]
This required alpha field contains the identifying name given to the Demand Side Inlet Node. This node is the inlet to the demand side of the loop.
Field: Demand Side Outlet Node Name[LINK]
This required alpha field contains the identifying name given to the Demand Side Outlet Node. This node is the outlet of the demand side of the loop.
Field: Demand Side Branch List Name[LINK]
This required alpha field contains the identifying name given to the Demand Side Branch List. The list referenced here should list all the branches on the demand side of the loop.
Field: Demand Side Connector List Name[LINK]
This alpha field contains the identifying name given to the Demand Side Connector List. The list referenced here should list the splitter and mixer on the demand side of the loop.
Field: Load Distribution Scheme[LINK]
The Load Distribution Scheme selects the algorithm used to sequence equipment operation in order to meet the plant loop demand. Currently, five schemes are functional:
Optimal operates each piece of equipment at its optimal part load ratio. Any remaining loop demand is distributed evenly to all of the components.
SequentialLoad loads each piece of equipment sequentially in the order specified in the PlantEquipmentList to its maximum part load ratio and will operate the last required piece of equipment between its minimum and maximum part load ratio in order to meet the loop demand.
UniformLoad evenly distributes the loop demand among all available components on the equipment list for a given load range. If some components do not have the capacity to meet the uniformly distributed load, the remaining load is distributed sequentially to the other available components.
SequentialUniformPLR loads all equipment on the PlantEquipmentList to a uniform part load ratio (PLR). Components are loaded sequentially based on the order specified in the PlantEquipmentList until each component is fully loaded, at which point the next subsequent component is added and the load is distributed uniformly based on PLR between the components.
UniformPLR will load all equipment on the PlantEquipmentList to a uniform part load ratio (PLR). No equipment will be loaded below its minimum PLR. If the total load is less than the sum of all equipment on the PlantEquipmentList operating at their respective minimum PLRs, then the last item in the equipment list is dropped and the load is distributed based on a uniform PLR for the remaining plant equipment.
Note: For all schemes, if the load for any individual component is less than the component load at the minimum PLR, the individual component model will false load or reduce duty cycle while operating at the minimum part load ratio until the load is met.
Field: Availability Manager List Name[LINK]
This alpha field contains the identifying name given to the System Availability Manager List.
Field: Plant Loop Demand Calculation Scheme[LINK]
There are two choices for plant loop demand calculations schemes in EnergyPlus: SingleSetpoint and DualSetpointDeadband.
SingleSetpoint - For the SingleSetpoint scheme, the plant loop is controlled to a single temperature setpoint. This requires a setpoint manager with Control Variable = Temperature to place a setpoint on the Loop Temperature Setpoint Node. The setpoint will be stored in the Node%TempSetpoint variable which may be reported using Output:Variable "System Node Setpoint Temperature." Examples of applicable setpoint managers include: SetpointManager:Scheduled, SetpointManager:OutdoorAirReset, SetpointManager:FollowOutdoorAirTemperature, etc. SingleSetpoint is the default.
DualSetpoint - For the DualSetpoint scheme, the plant loop is controlled to stay between a pair of high and low temperature setpoints. This requires one or two setpoint managers to place two setpoints on the Loop Temperature Setpoint Node. The setpoints will be stored in the Node%TempSetPointHi and Node%TempSetPointLo variables which may be reported using Output:Variable "System Node Setpoint High Temperature" and "System Node Setpoint Low Temperature." There is special setpoint manager, SetpointManager:Scheduled:DualSetpoint, which will place both the high and low setpoints with Control Variable = Temperature. Otherwise, two setpoint managers are required, one with Control Variable = MaximumTemperature and another with Control Variable = MinimumTemperature. The two setpoint managers may be the same kind or different, but care should be taken so that the MinimumTemperature is not set higher than the MaximumTemperature. Examples of applicable setpoint managers include: SetpointManager:Scheduled, SetpointManager:OutdoorAirReset, SetpointManager:FollowOutdoorAirTemperature, etc. Note that DualSetpoint is used only for plant loops with both heating and cooling supply equipment, such as a water loop heat pump system. When the loop temperature rises above the MaximumTemperature setpoint, then the loop will request cooling, and when the loop temperature is below the MinimumTemperature setpoint it will request heating. DualSetpoint cannot be used to control a single-mode loop, such as a hot water heating loop between operating between high and low boiler setpoints.
The plant loop demand calculation scheme determines the amount of heating or cooling necessary to bring the temperature of the Plant Loop to its setpoint(s). When this value is determined then the load distribution scheme explained in the previous section takes this value and distributes the load to the appropriate equipment. The demand calculation scheme determines how the load is calculated. See more information in the Engineering Document.
Field: Common Pipe Simulation[LINK]
This field specifies a primary-secondary plant loop simulation. When a common pipe option is specified, the plant side of the loop is the primary loop and the demand side of the loop is the secondary loop, and a pump object must be placed on the demand side inlet branch. The three options are “None”, “CommonPipe” and “TwoWayCommonPipe”. “None” means that there is no secondary loop and the plant loop is modeled as a single primary loop. “CommonPipe” means that the common pipe interface does not attempt any temperature control, it only satisfies secondary (demand side) flow requests. “TwoWayCommonPipe” allows control of the secondary (demand side) inlet temperature or the primary (plant side) inlet temperature by placing a setpoint on the corresponding node. If this field is left blank, it will default to “None”. If the field is set to “None” and the program finds a pump on the demand side it will result in a fatal error. If the field is set to “CommonPipe” or “TwoWayCommonPipe” and the program does not find a pump on the demand side it will result in a fatal error. The common pipe simulation is currently limited to simulating loop pumps, i.e. each pump should be placed on the inlet branch of the plant side or demand side of the loop.
Field: Pressure Simulation Type[LINK]
This field lets user to choose if this plant loop will be involved in a pressure drop calculation. This requires that at least one branch on the loop have pressure drop data. If not, an error will be thrown due to the input mismatch. Currently there are two pressure drop simulation types: “PumpPowerCorrection” and “LoopFlowCorrection”. In both of these methods, branch pressure drop data is used to calculate a dynamic loop pressure drop and is used to update pumping power accordingly. The flow correction method allows the user to enter information regarding the pressure curve of a constant speed pump so that the simulation can dynamically resolve the pressure vs. flow relationship in the plant loop. This is limited to constant speed pumps, as the variable speed pumps are expected to resolve as if it were controlled by a variable drive, so that they can inherently meet any pressure and flow demand required by the loop. This is also limited to “loop pumps”, where there is a single pump on the plant loop. Common pipe simulations and “branch pump” simulations are not compatible with this level of pressure simulation. See the documentation for the Pump:ConstantSpeed in order to determine required inputs for this pressure simulation method to be performed. In the pressure drop system, parallel flow rates are not resolved (to match the pressure drop for the parallel system). Enhancements to this calculation are planned which will allow parallel branch flow resolution. See the Engineering Reference document for more information on how this works.
Field: Loop Circulation Time[LINK]
This field specifies the time it takes the fluid to circulate through the entire loop. It is only used when Plant Loop Volume is set to autocalculate. The default is 2 minutes.
An example of this statement used in an IDF is:
In the above example input there is no system availability manager specified and the Demand Calculation Scheme will default to SingleSetpoint using a single setpoint manager. Common pipe simulation field in the above example will default to “NONE” since it is not specified.
Outputs[LINK]
In the following output variables, “Debug” denotes variables that are used primarily by the developers and whose names and application may be cryptic to users. .
HVAC,Average,Plant Supply Side Cooling Demand Rate [W]
HVAC,Average,Plant Supply Side Heating Demand Rate [W]
HVAC,Average,Plant Supply Side Inlet Mass Flow Rate [kg/s]
HVAC,Average,Plant Supply Side Inlet Temperature [C]
HVAC,Average,Plant Supply Side Outlet Temperature [C]
HVAC,Average,Plant Supply Side Not Distributed Demand Rate [W]
HVAC,Average,Plant Supply Side Unmet Demand Rate [W]
HVAC,Sum,Plant Solver Sub Iteration Count []
HVAC,Sum,Plant Solver Half Loop Calls Count []
HVAC,Average,Debug Plant Loop Bypass Fraction
HVAC,Average,Debug Plant Last Simulated Loop Side [-]
HVAC,Average,Plant Common Pipe Mass Flow Rate [Kg/s]
HVAC,Average,Plant Common Pipe Temperature [C]
HVAC,Average,Plant Common Pipe Flow Direction Status []
HVAC,Average,Plant Common Pipe Primary Mass Flow Rate [Kg/s]
HVAC,Average,Plant Common Pipe Secondary Mass Flow Rate [Kg/s]
HVAC,Average,Primary Side Common Pipe Flow Direction []
HVAC,Average,Secondary Side Common Pipe Flow Direction []
HVAC,Average,Plant Common Pipe Primary to Secondary Mass Flow Rate [Kg/s]
HVAC,Average,Plant Common Pipe Secondary to Primary Mass Flow Rate [Kg/s]
HVAC,Average,Plant System Cycle On Off Status []
HVAC,Average,Plant Demand Side Loop Pressure Difference [Pa]
HVAC,Average,Plant Supply Side Loop Pressure Difference [Pa]
HVAC,Average,Plant Loop Pressure Difference [Pa]
Plant Supply Side Cooling Demand Rate [W][LINK]
This is the value of the net demand required to meet the cooling setpoint of the loop. If the loop setpoint is met for the current HVAC timestep, Plant Supply Side Cooling Demand Rate will equal sum of the total cooling demand from the demand side coils on the loop. It will also equal the cooling output of all chillers (or other cooling equipment) on the loop less any pump heat added to the fluid. For example, for a chilled water loop with one chiller and one pump serving one chilled water coil: Plant Supply Side Cooling Demand Rate will equal the chiller evaporator heat transfer less the pump heat to fluid, and it will also equal the chilled water coil total cooling output.
If the plant loop setpoint is not met, Plant Supply Side Cooling Demand Rate will equal the sum of the total cooling demand from the demand side coils on the loop plus the additional cooling required to bring the loop flow to setpoint. If the loop remains off setpoint for successive timesteps, the demand required to return to setpoint will repeat in each timestep until the loop reaches setpoint. For this reason, Plant Supply Side Cooling Demand Rate should not be summed over time, because it will overstate the demand whenever the loop is off setpoint.
Plant Supply Side Heating Demand Rate [W][LINK]
This is the value of the net demand required to meet the heating setpoint of the loop. If the loop setpoint is met for the current HVAC timestep, Plant Supply Side Heating Demand Rate will equal sum of the total heating demand from the demand side coils on the loop. It will also equal the heating output of all boilers (or other cooling equipment) on the loop plus any pump heat added to the fluid. For example, for a hot water loop with one boiler and one pump serving one hot water coil: Plant Supply Side Heating Demand Rate will equal the boiler heat transfer plus the pump heat to fluid, and it will also equal the hot water coil total heating output.
If the plant loop setpoint is not met, Plant Supply Side Heating Demand Rate will equal the sum of the total heating demand from the demand side coils on the loop plus the additional heating required to bring the loop flow to setpoint. If the loop remains off setpoint for successive timesteps, the demand required to return to setpoint will repeat in each timestep until the loop reaches setpoint. For this reason, Plant Supply Side Heating Demand Rate should not be summed over time, because it will overstate the demand whenever the loop is off setpoint.
Plant Supply Side Inlet Mass Flow Rate [kg/s][LINK]
This is the value of the mass flow rate at the Inlet to Plant Loop on the supply side. There is not an associated Plant Loop outlet node flow rate since continuity must be maintained in the loop and the outlet must be the same.
Plant Supply Side Inlet Temperature [C][LINK]
This is the value of the temperature at the Inlet to the plant loop on the supply side.
Plant Supply Side Outlet Temperature [C][LINK]
This is the value of the temperature at the outlet to the plant loop on the supply side.
Plant Supply Side Not Distributed Demand Rate [W][LINK]
This is the value of the demand that could not be distributed to the plant equipment because of some constraint in the plant operation scheme. This is a record of the loop operation scheme supervisory controls after attempting to distribute the load. For example it would be non-zero in situations where the load is larger than the upper limit of capacities set for the plant equipment controls. This output is for before the equipment has actually been simulated whereas the separate output Plant Supply Side Unmet Demand Rate is for after the equipment has simulated.
Plant Supply Side Unmet Demand Rate [W][LINK]
This is the value of the demand NOT provided by the plant equipment to meet the heating or cooling setpoint of the loop. The value is positive when the plant equipment cannot meet the setpoint, and the value is negative when the plant equipment provides more than enough heating or cooling to meet the setpoint. A negative value can happen when the amount of demand is smaller than the minimum capacity of the equipment using the minimum part load ratio.
Plant Solver Sub Iteration Count [][LINK]
This is the count of iterations that the overall plant simulation used over the period of time being reported. This high-level output is from the plant solver used for all the plant loops and condenser loops in the model.
Plant Solver Half Loop Calls Count[LINK]
This is the count of calls to model individual half-loops that occurred during the overall plant simulation over the period of time being reported. This includes all the half-loops for both plant loops and condenser loops.
Plant Common Pipe Mass Flow Rate [Kg/s][LINK]
This output gives the magnitude of the flow through common pipe. The value is averaged over the reporting interval.
Plant Common Pipe Temperature [C][LINK]
This output gives the value of the temperature of the fluid flowing through common pipe. This value is averaged over the reporting interval.
Plant Common Pipe Flow Direction Status [][LINK]
This output gives the direction of flow in common pipe. The value is an integer and can be 0, 1 or 2. Since the output value is averaged over reporting interval, a non-integer value may be shown as an output when the reporting interval is not detailed. An output value of 0 means that there was no flow in common pipe. An output value of 1 means that the secondary flow is greater than primary flow, whereas a value of 2 means that primary flow is greater than secondary flow.
Plant Common Pipe Primary Mass Flow Rate [Kg/s][LINK]
This output variable gives the mass flow in the primary side common pipe leg in a Two-Way common pipe simulation. Value is averaged over the reporting interval.
Plant Common Pipe Secondary Mass Flow Rate [Kg/s][LINK]
This output variable gives the mass flow in the secondary side common pipe leg in a Two-Way common pipe simulation. Value is averaged over the reporting interval.
Primary Side Common Pipe Flow Direction [][LINK]
This output variable gives the direction of flow in a primary side common pipe leg in a Two-Way Common Pipe Simulation. A value of zero means there was no flow in the pipe. A value of 1 means the flow was from top to bottom in EnergyPlus loop schematic. So for primary side, a value of 1 means the flow is from Primary side inlet to Primary side outlet and a value of 2 means flow is from Primary side outlet to Primary side inlet.
Secondary Side Common Pipe Flow Direction [][LINK]
This output variable gives the direction of flow in a Secondary side common pipe leg in a Two-Way Common Pipe Simulation. A value of zero means there was no flow in the pipe. A value of 1 means the flow was from top to bottom in EnergyPlus loop schematic. So for Secondary side, a value of 1 means the flow is from Secondary side outlet to Secondary side inlet and a value of 2 means flow is from Secondary side inlet to Secondary side outlet. Note that this is opposite to the primary side common pipe.
Plant Common Pipe Primary to Secondary Mass Flow Rate [Kg/s][LINK]
This output variable gives the mass flow from primary to secondary side in a Two-Way common pipe simulation. Value is averaged over the reporting interval.
Plant Common Pipe Secondary to Primary Mass Flow Rate [Kg/s][LINK]
This output variable gives the mass flow from secondary to primary side in a Two-Way common pipe simulation. Value is averaged over the reporting interval.
Plant System Cycle On Off Status[LINK]
This field is the availability status of a Plant Loop. This status flag is a result of the calculations made by the System Availability Manager(s) listed in a System Availability Manager List. When a single availability manager is used in a System Availability Manager List, this is also the availability status reported by the specific availability manager (Ref. System Availability Manager Outputs). When multiple availability managers are used in a System Availability Manager List, the loop availability status is determine by the rules associated with Plant Loops (see rules described for Group – System Availability Managers). The control status outputs are represented using integers 0 through 2.. These integers represent NoAction (0), ForceOff (1), and CycleOn (2). Since the status output is averaged, the output result may not correspond to the values described here when output variable frequencies other than detailed are used. Use the “detailed” reporting frequency (Ref. Output:Variable object) to view the availability status at each simulation timestep.
Plant Demand Side Loop Pressure Difference [Pa][LINK]
This field allows the user to output the demand side pressure drop of a plant loop. This output is only recognized if a valid pressure simulation is being performed. To do this, the user must specify a pressure simulation type as an input in the PlantLoop object, and input at least one pressure drop curve on a branch of the plant loop. This particular output is only relevant if the user puts that curve on the demand side of the loop.
Plant Supply Side Loop Pressure Difference [Pa][LINK]
This field allows the user to output the supply side pressure drop of a plant loop. This output is only recognized if a valid pressure simulation is being performed. To do this, the user must specify a pressure simulation type as an input in the PlantLoop object, and input at least one pressure drop curve on a branch of the plant loop. This particular output is only relevant if the user puts that curve on the supply side of the loop.
Plant Loop Pressure Difference [Pa][LINK]
This output is the total pressure drop of a plant loop. This output is only recognized if a valid pressure simulation is being performed. To do this, the user must specify a pressure simulation type as an input in the PlantLoop object, and input at least one pressure drop curve on a branch of the plant loop. This particular output is relevant regardless of the location of pressure drop curves: demand side, supply side, or both.
The following advanced output variables are also available for plant loops (and condenser loops) when advanced output variables are requested (e.g. “Output:Diagnostics, DisplayAdvancedReportVariable;”).
HVAC,Average,Plant Demand Side Lumped Capacitance Temperature [C]
HVAC,Average,Plant Supply Side Lumped Capacitance Temperature [C]
HVAC,Average,Plant Demand Side Lumped Capacitance Heat Transport Rate [W]
HVAC,Average,Plant Supply Side Lumped Capacitance Heat Transport Rate [W]
HVAC,Average,Plant Demand Side Lumped Capacitance Heat Storage Rate [W]
HVAC,Average,Plant Supply Side Lumped Capacitance Heat Storage Rate [W]
HVAC,Sum,Plant Demand Side Lumped Capacitance Excessive Storage Time [hr]
HVAC,Sum,Plant Supply Side Lumped Capacitance Excessive Storage Time [hrW]
HVAC,Average,Plant Component Distributed Demand Rate [W]
Plant Demand Side Lumped Capacitance Temperature [C][LINK]
Plant Supply Side Lumped Capacitance Temperature [C][LINK]
These two outputs are the temperature of the plant (or condenser) loop’s working fluid where the two half-loops interface together. The program models heat capacitance in the volume of fluid inside the plant loop itself using two simple models for “well-stirred” tanks located at each of the half-loop inlet and outlet pairs. These tank models also receive the heat transferred to the fluid by the work done by pumping and resulting friction heating. One output is for the point where the fluid leaves the supply side and enters the demand side. The other output is for the point where the fluid leaves the demand side and enters the supply side.
Plant Demand Side Lumped Capacitance Heat Transport Rate [C][LINK]
Plant Supply Side Lumped Capacitance Heat Transport Rate [C][LINK]
These two outputs are the heat transfer rate to the the plant (or condenser) loop’s working fluid in the two half-loops. The program models heat capacitance in the volume of fluid inside the plant loop itself using two simple models for well-stirred tanks located at each of the half-loop inlet and outlet pairs. These tank models also receive the heat transferred to the fluid by the work done by pumping and resulting friction heating. One output is for the point where the fluid leaves the supply side and enters the demand side. The other output is for the point where the fluid leaves the demand side and enters the supply side.
Plant Demand Side Lumped Capacitance Heat Storage Rate [C][LINK]
Plant Supply Side Lumped Capacitance Heat Storage Rate [C][LINK]
These two outputs are the heat storage rate of the plant (or condenser) loop’s working fluid in the two half-loops. The program models heat capacitance in the volume of fluid inside the plant loop itself using two simple models for well-stirred tanks located at each of the half-loop inlet and outlet pairs. These tank models also receive the heat transferred to the fluid by the work done by pumping and resulting friction heating. One output is for the point where the fluid leaves the supply side and enters the demand side. The other output is for the point where the fluid leaves the demand side and enters the supply side.
Plant Demand Side Lumped Capacitance Excessive Storage Time [C][LINK]
Plant Supply Side Lumped Capacitance Excessive Storage Time [C][LINK]
These two outputs are the excess storage time of the plant (or condenser) loop’s working fluid in the two half-loops. The excess storage time is determined by adding the time when the heat storage rate exceeds the heat transfer rate into the two half-loops at each time step. The program models heat capacitance in the volume of fluid inside the plant loop itself using two simple models for well-stirred tanks located at each of the half-loop inlet and outlet pairs. These tank models also receive the heat transferred to the fluid by the work done by pumping and resulting friction heating. One output is for the point where the fluid leaves the supply side and enters the demand side. The other output is for the point where the fluid leaves the demand side and enters the supply side.
Plant Component Distributed Demand Rate [W][LINK]
This output is available for every component on every branch in a plant (or condenser) loop and shows the outcome of the load dispatch performed by the operation schemes. This the load in watts passed from the supervisor routines to the equipment component models. This provides a record of what a particular component was asked to do by the supervisory routines. This can be useful for diagnosing issues in operation schemes when a component or loop is failing to meet the load.
CondenserLoop[LINK]
The condenser loop input is very similar to that for the plant loop. As of version 7, the two loops are modeled the same way and inside the program all condenser loops are just plant loops. (In future versions of the program, this CondenserLoop object might be deprecated and these loops will be described using the PlantLoop object.) The main differences are the applicable components and operation schemes. This is depicted in the following diagram.
Inputs[LINK]
Field: Name[LINK]
This alpha field is used as an identifying field for the condenser loop.
Field: Fluid Type[LINK]
This alpha field must be a keyword selected from the list of available fluids for an EnergyPlus plant loop. Either Water or UserDefinedFluidType may be used. If the UserDefinedFluidType keyword is used, the following input field i.e. User Defined Fluid Type must have a value (namely the name of a FluidProperties:GlycolConcentration object).
Field: User Defined Fluid Type[LINK]
This alpha field must be specified when the previous field is set to UserDefinedFluidType otherwise it could be left blank. Water, EthyleneGlycol, and PropyleneGlycol are all “built-in” fluids for EnergyPlus (that is, all of the appropriate properties are contained within the program). If the fluid specified here is a mixture of water and ethylene or propylene glycol, then only FluidProperties:GlycolConcentration objects need to be specified and the name of the appropriate one is used here. For another water/glycol mixture, a complete set of fluid property data (FluidProperties:Name and FluidProperties:Temperature objects plus multiple FluidProperties:Concentration objects for specific heat, density, etc.) must be specified (Ref dataset: GlycolPropertiesRefData.idf).
Field: Condenser Equipment Operation Scheme Name[LINK]
This alpha field is used as an identifying field for the condenser operation scheme. This field ties to the Condenser Operation Schemes input structure, which must also be defined.
Field: Condenser Loop Temperature Setpoint Node Name[LINK]
This alpha field is used to identify the node which the Loop Manager will access the temperature setpoint that it will try to maintain. This is typically the Condenser Loop Supply Side Outlet Node so that it will not interfere with component temperature setpoints. An associated temperature setpoint manager will need to be defined.
Field: Maximum Loop Temperature[LINK]
This numeric field contains the maximum allowable temperature in Celsius for this loop.
Field: Minimum Loop Temperature[LINK]
This numeric field contains the minimum allowable temperature in Celsius for this loop. This minimum loop temperature is used by the cooling towers to make sure that the minimum is not violated to keep the equipment safe. The minimum is also used to trigger the minimum temperature warning and will notify the user if it gets too low.
Field: Maximum Loop Flow Rate[LINK]
This numeric field contains the maximum loop flow rate in cubic meters per second. This field is autosizable.
Field: Minimum Loop Flow Rate[LINK]
This numeric field contains the minimum loop flow rate in cubic meters per second.
Field: Condenser Loop Volume[LINK]
Volume of the condenser loop in m\(^{3}\). This numeric field contains the loop volume for the entire loop, i.e., both the demand side and the supply side. This is used for the loop capacitance calculation. Loop volume (m\(^{3}\)) could be calculated from pipe size data but this is not usually known. If zero volume is specified the loop has no fluid heat capacity. If a very large capacitance is specified unrealistic time delay may result and there may be poor response to changes in loop setpoint temperature. The autocalculate option sets the loop volume to the product of the Maximum Loop Flow Rate and the user input for Loop Circulation Time which defaults to 2 minutes (see below). This calculation is described in the Engineering Reference manual.
Field: Condenser Side Inlet Node Name[LINK]
This required alpha field contains the identifying name given to the Condenser Side Inlet Node. This node is the inlet to the supply side of the loop.
Field: Condenser Side Outlet Node Name[LINK]
This required alpha field contains the identifying name given to the Condenser Side Outlet Node. This node is the outlet of the supply side of the loop.
Field: Condenser Side Branch List Name[LINK]
This required alpha field contains the identifying name given to the Condenser Side Branch List. The list referenced here should list all the branches on the supply side of the loop.
Field: Condenser Side Connector List Name[LINK]
This required alpha field contains the identifying name given to the Condenser Side Connector List. The list referenced here should list the splitter and mixer on the supply side of the loop.
Field: Demand Side Inlet Node Name[LINK]
This required alpha field contains the identifying name given to the Demand Side Inlet Node. This node is the inlet to the demand side of the loop.
Field: Demand Side Outlet Nodes Name[LINK]
This required alpha field contains the identifying name given to the Demand Side Outlet Node. This node is the outlet of the demand side of the loop.
Field: Condenser Demand Side Branch List Name[LINK]
This required alpha field contains the identifying name given to the Demand Side Branch List. The list referenced here should list all the branches on the demand side of the loop.
Field: Condenser Demand Side Connector List Name[LINK]
This required alpha field contains the identifying name given to the Demand Side Connector List. The list referenced here should list the splitter and mixer on the demand side of the loop.
Field: Load Distribution Scheme[LINK]
This alpha field contains the Load Distribution Scheme Keyword. The Load Distribution Scheme selects the algorithm used to sequence equipment operation in order to meet the plant loop demand. Currently, five schemes are functional. Optimal operates each piece of equipment at its optimal part load ratio and will operate the last component between its minimum and maximum part load ratio in order to meet the loop demand. SequentialLoad loads each piece of equipment sequentially in the order specified in the PlantEquipmentList to its maximum part load ratio and will operate the last required piece of equipment between its minimum and maximum part load ratio in order to meet the loop demand. UniformLoad evenly distributes the loop demand among all available components on the equipment list for a given load range. SequentialUniformPLR loads all equipment on the PlantEquipmentList to a uniform part load ratio (PLR). Components are loaded sequentially based on the order specified in the PlantEquipmentList until each component is fully loaded, at which point the next subsequent component is added and the load is distributed uniformly based on PLR between the components. UniformPLR will load all equipment on the PlantEquipmentList to a uniform part load ratio (PLR). No equipment will be loaded below its minimum PLR. If the total load is less than the sum of all equipment on the PlantEquipmentList operating at their respective minimum PLRs, then the last item in the equipment list is dropped and the load is distributed based on a uniform PLR for the remaining plant equipment.
Note: For all schemes, if the load for any individual component is less than the component load at the minimum PLR, the individual component model will false load or reduce duty cycle while operating at the minimum part load ratio until the load is met.
Field: Pressure Simulation Type[LINK]
This field lets user to choose if this plant loop will be involved in a pressure drop calculation. This requires that at least one branch on the loop have pressure drop data. If not, an error will be thrown due to the input mismatch. Currently there are two pressure drop simulation types: “PumpPowerCorrection” and “LoopFlowCorrection”. In both of these methods, branch pressure drop data is used to calculate a dynamic loop pressure drop and is used to update pumping power accordingly. The flow correction method allows the user to enter information regarding the pressure curve of a constant speed pump so that the simulation can dynamically resolve the pressure vs. flow relationship in the plant loop. This is limited to constant speed pumps, as the variable speed pumps are expected to resolve as if it were controlled by a variable drive, so that they can inherently meet any pressure and flow demand required by the loop. This is also limited to “loop pumps”, where there is a single pump on the plant loop. Common pipe simulations and “branch pump” simulations are not compatible with this level of pressure simulation. See the documentation for the Pump:ConstantSpeed in order to determine required inputs for this pressure simulation method to be performed. In the pressure drop system, parallel flow rates are not resolved (to match the pressure drop for the parallel system). Enhancements to this calculation are planned which will allow parallel branch flow resolution. See the Engineering Reference document for more information on how this works.
Field: Loop Circulation Time[LINK]
This field specifies the time it takes the fluid to circulate through the entire loop. It is only used when Condenser Loop Volume is set to autocalculate. The default is 2 minutes.
An example of this statement used in an IDF is:
Outputs[LINK]
HVAC,Average,Plant Supply Side Cooling Demand Rate [W]
HVAC,Average,Plant Supply Side Heating Demand Rate [W]
HVAC,Average,Plant Supply Side Inlet Mass Flow Rate [kg/s]
HVAC,Average,Plant Supply Side Inlet Temperature [C]
HVAC,Average,Plant Supply Side Outlet Temperature [C]
HVAC,Average,Cond Loop Demand Not Distributed [W]
HVAC,Average,Plant Supply Side Unmet Demand Rate [W]
HVAC,Average,Plant Demand Side Loop Pressure Difference [Pa]
HVAC,Average,Plant Supply Side Loop Pressure Difference [Pa]
HVAC,Average,Plant Loop Pressure Difference [Pa]
Plant Supply Side Cooling Demand Rate [W][LINK]
This is the value of the net demand required to meet the cooling setpoint of the loop. If the loop setpoint is met for the current HVAC timestep, Plant Supply Side Cooling Demand Rate will equal sum of the total cooling demand from the demand side components on the loop (typically condenser coils of chillers, etc.). It will also equal the cooling output of all condensing equipment such as cooling towers on the loop less any pump heat added to the fluid. For example, for a condenser loop with one tower and one pump serving one chiller, Plant Supply Side Cooling Demand Rate will equal the tower water-side heat transfer less the pump heat to fluid, and it will also equal the chiller condenser heat transfer rate.
If the condenser loop setpoint is not met, Plant Supply Side Cooling Demand Rate will equal the sum of the total cooling demand from the demand side components on the loop plus the additional cooling required to bring the loop flow to setpoint. If the loop remains off setpoint for successive timesteps, the demand required to return to setpoint will repeat in each timestep until the loop reaches setpoint. For this reason, Plant Supply Side Cooling Demand Rate should not be summed over time, because it will overstate the demand whenever the loop is off setpoint.
Plant Supply Side Heating Demand Rate [W][LINK]
This is the value of the net demand required to meet the heating setpoint of the loop. If the loop setpoint is met for the current HVAC timestep, Plant Supply Side Heating Demand Rate will equal sum of the total heating demand from the demand side components on the loop. It will also equal the heating output of all heating equipment on the supply side of the loop plus any pump heat added to the fluid. For example, for a condenser loop with one ground loop heat exchanger and one pump serving one water-to-water heat pump, Plant Supply Side Heating Demand Rate will equal the ground loop heat transfer plus the pump heat to fluid, and it will also equal the heat pump condenser side heat transfer rate.
If the condenser loop setpoint is not met, Plant Supply Side Heating Demand Rate will equal the sum of the total heating demand from the demand side components on the loop plus the additional heating required to bring the loop flow to setpoint. If the loop remains off setpoint for successive timesteps, the demand required to return to setpoint will repeat in each timestep until the loop reaches setpoint. For this reason, Plant Supply Side Heating Demand Rate should not be summed over time, because it will overstate the demand whenever the loop is off setpoint.
Plant Supply Side Inlet Mass Flow Rate [kg/s][LINK]
This is the value of the mass flow rate at the Inlet to Condenser Loop on the supply side. There is not an associated Condenser Loop outlet node flow rate since continuity must be maintained in the loop and the outlet must be the same.
Plant Supply Side Inlet Temperature [C][LINK]
This is the value of the temperature at the Inlet to the condenser loop on the supply side.
Cond Loop OutletNode Temperature [C][LINK]
This is the value of the temperature at the outlet to the condenser loop on the supply side.
Cond Loop Demand Not Distributed [W][LINK]
This is the value of the demand that could not be distributed to the condenser equipment because of some constraint in the operation scheme. This is a record of the loop operation scheme supervisory controls after attempting to distribute the load. For example it would be non-zero in situations where the load is larger than the upper limit of capacities set for the condenser equipment controls. This output is for before the equipment has actually been simulated whereas the separate output Plant Supply Side Unmet Demand Rate is for after the equipment has simulated.
Plant Supply Side Unmet Demand Rate [W][LINK]
This is the value of the demand NOT provided by the condenser equipment to meet the heating or cooling setpoint of the loop. The value is positive when the condenser equipment cannot meet the setpoint, and the value is negative when the condenser equipment provides more than enough heating or cooling to meet the setpoint. A negative value can happen when the amount of demand is smaller than the minimum capacity of the equipment using the minimum part load ratio.
Plant Demand Side Loop Pressure Difference [Pa][LINK]
This field is the demand side pressure drop of a condenser loop. This output is only recognized if a valid pressure simulation is being performed. To do this, the user must specify a pressure simulation type as an input in the CondenserLoop object, and input at least one pressure drop curve on a branch of the plant/condenser loop. This particular output is only relevant if the user puts that curve on the demand side of the loop.
Plant Supply Side Loop Pressure Difference [Pa][LINK]
This field is the supply side pressure drop of a condenser loop. This output is only recognized if a valid pressure simulation is being performed. To do this, the user must specify a pressure simulation type as an input in the CondenserLoop object, and input at least one pressure drop curve on a branch of the plant/condenser loop. This particular output is only relevant if the user puts that curve on the supply side of the loop.
Plant Loop Pressure Difference [Pa][LINK]
This field is the total pressure drop of a condenser loop. This output is only recognized if a valid pressure simulation is being performed. To do this, the user must specify a pressure simulation type as an input in the CondenserLoop object, and input at least one pressure drop curve on a branch of the plant/condenser loop. This particular output is relevant regardless of the location of pressure drop curves: demand side, supply side, or both.
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This documentation is made available under the EnergyPlus Open Source License v1.0.