Plant Load Profile[LINK]
The LoadProfile:Plant
object is used to simulate a scheduled demand profile. This
can be useful when the building loads are already known.
Demanded load and flow rate are schedules specified in the
object definition. The load profile can specify heating and
cooling loads. Cooling loads are entered as negative numbers.
The actual load met is dependent on the performance of the
supply loop components.
The LoadProfile:Plant
object must be connected on the demand side of the plant loop.
If desired, multiple LoadProfile:Plant
objects can be combined in series and/or parallel.
Calculation Model[LINK]
Plant Load
Profile in the Water Loop[LINK]
The LoadProfile:Plant
object in the water loop calculates the outlet water
temperature based on the inlet water temperature from the
plant loop and user inputs for the scheduled plant load and
the requested flow rate. The calculation can be expressed
with the equation:
\[{T_{out}} = {T_{in}} -
\frac{{{Q_{load}}}}{{\dot m{c_p}}}\]
where
\({T_{out}}\) = the
outlet water temperature
\({T_{in}}\) = the inlet
water temperature
\({Q_{load}}\) = the
scheduled plant load
\(\dot m\) = the water
mass flow rate
\({c_p}\) = the specific
heat of water
The user requested flow rate is not always available from
the plant loop. The actual flow rate used in the calculation
is the lesser of the user requested value and the plant
available value.
Note that the LoadProfile:Plant
object can still request and receive flow even if the
scheduled plant load is zero. In this case the outlet
temperature will be the same as the inlet temperature. This
allows users to drive the plant loop flow without necessarily
affecting the loop temperature.
For reporting purposes the energy consumption of the object
is calculated using the equation:
\[E = {Q_{load}}\Delta
t\]
where
\(E\) = the energy
consumption
\({Q_{load}}\) = the
scheduled plant load
\(\Delta t\) = the time
step interval
Plant Load
Profile in the Steam Loop[LINK]
The LoadProfile:Plant
object in the steam loop calculates the outlet steam flow rate
based on the inlet condensate temperature from the plant loop
and user inputs for the scheduled plant load. This model
accounts for the latent heat transfer and sensible cooling of
water. Steam enters the load profile component at quality
equal to 1.0, at saturation temperature and leaves the load
profile component with desired degree of sub cooling. The
user inputs the desired degree of subcooling, which determines
the condensate outlet condition from the load profile
component. The calculation can be expressed with the
equation:
\[{\dot m_{out}}\,\,\,\, =
\,\,\,\,\,\frac{{{Q_{load}}}}{{{h_{fg}} + {c_{p,condensate}}
\times \Delta {T_{sc}}}}\]
where
\({\dot m_{out}}\) = the
outlet steam mass flow rate
\({Q_{load}}\) = the
scheduled plant load
\({h_{fg}}\) = the steam
latent heat of vaporization
\({ \Delta {T_{sc}}}\) =
the temperature difference between saturation temperature and
condensate temperature
\({c_{p,condensate}}\) =
the condensate heat capacity
Plant Load Profile[LINK]
The LoadProfile:Plant object is used to simulate a scheduled demand profile. This can be useful when the building loads are already known. Demanded load and flow rate are schedules specified in the object definition. The load profile can specify heating and cooling loads. Cooling loads are entered as negative numbers. The actual load met is dependent on the performance of the supply loop components.
The LoadProfile:Plant object must be connected on the demand side of the plant loop. If desired, multiple LoadProfile:Plant objects can be combined in series and/or parallel.
Calculation Model[LINK]
Plant Load Profile in the Water Loop[LINK]
The LoadProfile:Plant object in the water loop calculates the outlet water temperature based on the inlet water temperature from the plant loop and user inputs for the scheduled plant load and the requested flow rate. The calculation can be expressed with the equation:
\[{T_{out}} = {T_{in}} - \frac{{{Q_{load}}}}{{\dot m{c_p}}}\]
where
\({T_{out}}\) = the outlet water temperature
\({T_{in}}\) = the inlet water temperature
\({Q_{load}}\) = the scheduled plant load
\(\dot m\) = the water mass flow rate
\({c_p}\) = the specific heat of water
The user requested flow rate is not always available from the plant loop. The actual flow rate used in the calculation is the lesser of the user requested value and the plant available value.
Note that the LoadProfile:Plant object can still request and receive flow even if the scheduled plant load is zero. In this case the outlet temperature will be the same as the inlet temperature. This allows users to drive the plant loop flow without necessarily affecting the loop temperature.
For reporting purposes the energy consumption of the object is calculated using the equation:
\[E = {Q_{load}}\Delta t\]
where
\(E\) = the energy consumption
\({Q_{load}}\) = the scheduled plant load
\(\Delta t\) = the time step interval
Plant Load Profile in the Steam Loop[LINK]
The LoadProfile:Plant object in the steam loop calculates the outlet steam flow rate based on the inlet condensate temperature from the plant loop and user inputs for the scheduled plant load. This model accounts for the latent heat transfer and sensible cooling of water. Steam enters the load profile component at quality equal to 1.0, at saturation temperature and leaves the load profile component with desired degree of sub cooling. The user inputs the desired degree of subcooling, which determines the condensate outlet condition from the load profile component. The calculation can be expressed with the equation:
\[{\dot m_{out}}\,\,\,\, = \,\,\,\,\,\frac{{{Q_{load}}}}{{{h_{fg}} + {c_{p,condensate}} \times \Delta {T_{sc}}}}\]
where
\({\dot m_{out}}\) = the outlet steam mass flow rate
\({Q_{load}}\) = the scheduled plant load
\({h_{fg}}\) = the steam latent heat of vaporization
\({ \Delta {T_{sc}}}\) = the temperature difference between saturation temperature and condensate temperature
\({c_{p,condensate}}\) = the condensate heat capacity
Documentation content copyright © 1996-2026 The Board of Trustees of the University of Illinois and the Regents of the University of California through the Ernest Orlando Lawrence Berkeley National Laboratory. All rights reserved. EnergyPlus is a trademark of the US Department of Energy.
This documentation is made available under the EnergyPlus Open Source License v1.0.