Buildings.Controls.SetPoints

Information

Package Content

Name	Description
Examples	Collection of models that illustrate model use and test models
HotWaterTemperatureReset	Block to compute the supply and return set point of heating systems
OccupancySchedule	Occupancy schedule with look-ahead

Buildings.Controls.SetPoints.HotWaterTemperatureReset

Information

The parameter dTOutHeaBal can be used to shift the heating curve to account for the fact that solar heat gains and heat gains from equipment and people make up for some of the transmission losses. For example, in energy efficient houses, the heating may not be switched on above 12 degree Celsius, even if a room temperature of 20 degree is required. In such a situation, set dTOutHeaBal=20-12=8 Kelvin to shift the heating curve.

Parameters

Type	Name	Default	Description
Real	m	1.3	Exponent for heat transfer
Boolean	use_TRoo_in	false	Get the room temperature set point from the input connector
Temperature	TRoo	293.15	Fixed value of room air temperature set point [K]
TemperatureDifference	dTOutHeaBal	8	Offset for heating curve [K]
Nominal conditions
Temperature	TSup_nominal		Supply temperature [K]
Temperature	TRet_nominal		Return temperature [K]
Temperature	TRoo_nominal	293.15	Room temperature [K]
Temperature	TOut_nominal		Outside temperature [K]

Connectors

Type	Name	Description
input RealInput	TRoo_in	Room air temperature set point [K]
input RealInput	TOut	Outside temperature [K]
output RealOutput	TSup	Setpoint for supply temperature [K]
output RealOutput	TRet	Setpoint for return temperature [K]

Modelica definition

block HotWaterTemperatureReset 
  "Block to compute the supply and return set point of heating systems"
  extends Modelica.Blocks.Interfaces.BlockIcon;


  parameter Real m = 1.3 "Exponent for heat transfer";
  parameter Modelica.SIunits.Temperature TSup_nominal "Supply temperature";
  parameter Modelica.SIunits.Temperature TRet_nominal "Return temperature";
  parameter Modelica.SIunits.Temperature TRoo_nominal = 293.15 
    "Room temperature";
  parameter Modelica.SIunits.Temperature TOut_nominal "Outside temperature";

  parameter Boolean use_TRoo_in = false 
    "Get the room temperature set point from the input connector";
  parameter Modelica.SIunits.Temperature TRoo = 293.15 
    "Fixed value of room air temperature set point";
  parameter Modelica.SIunits.TemperatureDifference dTOutHeaBal = 8 
    "Offset for heating curve";
  Modelica.Blocks.Interfaces.RealInput TRoo_in(final quantity="ThermodynamicTemperature",
                                               final unit = "K", displayUnit = "degC", min=0) if 
          use_TRoo_in "Room air temperature set point";

  Modelica.Blocks.Interfaces.RealInput TOut(final quantity="ThermodynamicTemperature",
                                            final unit = "K", displayUnit = "degC", min=0) 
    "Outside temperature";
  Modelica.Blocks.Interfaces.RealOutput TSup(final quantity="ThermodynamicTemperature",
                                            final unit = "K", displayUnit = "degC", min=0) 
    "Setpoint for supply temperature";
  Modelica.Blocks.Interfaces.RealOutput TRet(final quantity="ThermodynamicTemperature",
                                            final unit = "K", displayUnit = "degC", min=0) 
    "Setpoint for return temperature";

protected 
  Modelica.Blocks.Interfaces.RealInput TRoo_in_internal(final quantity="ThermodynamicTemperature",
                                                        final unit = "K", displayUnit = "degC", min=0) 
    "Needed to connect to conditional connector";
  Real qRel "Relative heat load = Q_flow/Q_flow_nominal";
  Modelica.SIunits.Temperature TOutOffSet 
    "Effective outside temperature for heat transfer (takes into account room heat gains)";
  parameter Modelica.SIunits.Temperature TOutOffSet_nominal =  TOut_nominal + dTOutHeaBal 
    "Effective outside temperature for heat transfer at nominal conditions (takes into account room heat gains)";

equation 
  connect(TRoo_in, TRoo_in_internal);
  if not use_TRoo_in then
    TRoo_in_internal = TRoo;
  end if;
 TOutOffSet = TOut + dTOutHeaBal;
 // Relative heating load, compared to nominal conditions
 qRel = max(0, (TRoo_in_internal-TOutOffSet)/(TRoo_nominal-TOutOffSet_nominal));
 TSup = TRoo_in_internal
          + ((TSup_nominal+TRet_nominal)/2-TRoo_in_internal) * qRel^(1/m)
          + (TSup_nominal-TRet_nominal)/2 * qRel;
 TRet = TSup - qRel * (TSup_nominal-TRet_nominal);
end HotWaterTemperatureReset;

Buildings.Controls.SetPoints.OccupancySchedule

Information

This model outputs whether the building is currently occupied, and how long it will take until the next time when the building will be occupied or non-occupied. The latter may be used, for example, to start a ventilation system half an hour before occupancy starts in order to ventilate the room.

The occupancy is defined by a time schedule of the form

  occupancy = 3600*{7, 12, 14, 19}

block OccupancySchedule "Occupancy schedule with look-ahead"
  extends Modelica.Blocks.Interfaces.BlockIcon;

  parameter Real occupancy[:]=3600*{7, 19} 
    "Occupancy table, each entry switching occupancy on or off";
  parameter Boolean firstEntryOccupied = true 
    "Set to true if first entry in occupancy denotes a changed from unoccupied to occupied";
  parameter Modelica.SIunits.Time startTime = 0 "Start time of periodicity";
  parameter Modelica.SIunits.Time endTime =   86400 "End time of periodicity";

  Modelica.Blocks.Interfaces.RealOutput tNexNonOcc 
    "Time until next non-occupancy";
  Modelica.Blocks.Interfaces.RealOutput tNexOcc "Time until next occupancy";
  Modelica.Blocks.Interfaces.BooleanOutput occupied 
    "Outputs true if occupied at current time";

protected 
  final parameter Modelica.SIunits.Time period = endTime-startTime;
  final parameter Integer nRow = size(occupancy,1);

  output Integer nexStaInd "Next index when occupancy starts";
  output Integer nexStoInd "Next index when occupancy stops";

  output Integer iPerSta 
    "Counter for the period in which the next occupancy starts";
  output Integer iPerSto 
    "Counter for the period in which the next occupancy stops";
  output Modelica.SIunits.Time schTim 
    "Time in schedule (not exceeding max. schedule time)";
  output Modelica.SIunits.Time tMax "Maximum time in schedule";
  output Modelica.SIunits.Time tOcc "Time when next occupancy starts";
  output Modelica.SIunits.Time tNonOcc "Time when next non-occupancy starts";
initial algorithm 
  // Check parameters for correctness
 assert(mod(nRow, 2) < 0.1,
   "The parameter \"occupancy\" must have an even number of elements.\n");
 assert(startTime < occupancy[1],
   "The parameter \"startTime\" must be smaller than the first element of \"occupancy\"."
   + "\n   Received startTime    = " + realString(startTime)
   + "\n            occupancy[1] = " + realString(occupancy[1]));
 assert(endTime > occupancy[nRow],
   "The parameter \"endTime\" must be greater than the last element of \"occupancy\"."
   + "\n   Received endTime      = " + realString(endTime)
   + "\n            occupancy[" + integerString(nRow) +
     "] = " + realString(occupancy[nRow]));
  for i in 1:nRow-1 loop
    assert(occupancy[i] < occupancy[i+1],
      "The elements of the parameter \"occupancy\" must be strictly increasing.");
  end for;
 // Initialize variables
 // if the firstEntryOccupied == false, then set the current time to the
 // the time when occupancy starts.
 tOcc    :=if firstEntryOccupied then occupancy[1] else time;
 tNonOcc :=if firstEntryOccupied then time else occupancy[1];

 iPerSta   := 0;
 iPerSto   := 0;
 nexStaInd := if firstEntryOccupied then 1 else 2;
 nexStoInd := if firstEntryOccupied then 2 else 1;
 occupied := not firstEntryOccupied;
 tOcc    := occupancy[nexStaInd];
 tNonOcc := occupancy[nexStoInd];
algorithm 
  assert(startTime < endTime, "Wrong parameter values.");
  tMax :=endTime;
  schTim :=startTime + mod(time-startTime, period);

  // Changed the index that computes the time until the next occupancy
  when time >= pre(occupancy[nexStaInd])+ iPerSta*period then
    nexStaInd :=nexStaInd + 2;
    occupied := not occupied;
    // Wrap index around
    if nexStaInd > nRow then
       nexStaInd := if firstEntryOccupied then 1 else 2;
       iPerSta := iPerSta + 1;
    end if;
    tOcc := occupancy[nexStaInd] + iPerSta*(period);
  end when;

  // Changed the index that computes the time until the next non-occupancy
  when time >= pre(occupancy[nexStoInd])+ iPerSto*period then
    nexStoInd :=nexStoInd + 2;
    occupied := not occupied;
    // Wrap index around
    if nexStoInd > nRow then
       nexStoInd := if firstEntryOccupied then 2 else 1;
       iPerSto := iPerSto + 1;
    end if;
    tNonOcc := occupancy[nexStoInd] + iPerSto*(period);
  end when;

 tNexOcc    := tOcc-time;
 tNexNonOcc := tNonOcc-time;
end OccupancySchedule;