From dbade3c6053947afeb9976bc0840a9ac483d9dca Mon Sep 17 00:00:00 2001
From: jelgerjansen <jelgerjansen@hotmail.com>
Date: Mon, 9 Dec 2024 17:22:03 +0100
Subject: [PATCH] Reapply "Merge remote-tracking branch master into
 project_itz_fixes_v2 (issue 1337)"

This reverts commit 841a90714a9e563e6b8f1c2aceba4f282065244a.
---
 IDEAS/Buildings/Components/BoundaryWall.mo    | 34 +++++---
 .../Components/Interfaces/DummyConnection.mo  | 25 +++++-
 .../Components/Interfaces/PartialSurface.mo   | 13 +--
 .../Components/Interfaces/PartialZone.mo      | 26 ++++--
 .../Components/Interfaces/ZoneBus.mo          | 16 ++--
 .../Interfaces/ZoneBusVarMultiplicator.mo     | 19 +++-
 IDEAS/Buildings/Components/InternalWall.mo    | 86 ++++++++++++++-----
 IDEAS/Buildings/Components/OuterWall.mo       |  9 +-
 IDEAS/Buildings/Components/SlabOnGround.mo    | 17 ++--
 IDEAS/Buildings/Components/Window.mo          | 18 ++--
 IDEAS/Buildings/Components/Zone.mo            |  7 ++
 11 files changed, 200 insertions(+), 70 deletions(-)

diff --git a/IDEAS/Buildings/Components/BoundaryWall.mo b/IDEAS/Buildings/Components/BoundaryWall.mo
index 0cccb8adb8..3a84fe5e9c 100644
--- a/IDEAS/Buildings/Components/BoundaryWall.mo
+++ b/IDEAS/Buildings/Components/BoundaryWall.mo
@@ -4,31 +4,36 @@ model BoundaryWall "Opaque wall with optional prescribed heat flow rate or tempe
     final custom_q50=0,
     final use_custom_q50=true,
     final nWin=1,
-    QTra_design=U_value*A*(273.15 + 21 - TRef_a),
     dT_nominal_a=-1,
     add_door=false,
+    final QTra_design(fixed=false),
     layMul(disableInitPortB=use_T_in or use_T_fixed, monLay(monLayDyn(each
             addRes_b=(sim.lineariseDymola and (use_T_in or use_T_fixed))))));
 
+  parameter Boolean use_T_in = false
+    "Use a temperature boundary condition which is read from the input connector T_in"
+    annotation(Dialog(group="Boundary conditions"));
   parameter Boolean use_T_fixed = false
-    "Get the boundary temperature from the input connector"
+    "Use a fixed temperature boundary condition which is read from the parameter T_fixed"
     annotation(Dialog(group="Boundary conditions"));
   parameter Modelica.Units.SI.Temperature T_fixed=294.15
     "Fixed boundary temperature"
-    annotation (Dialog(group="Boundary conditions", enable=use_T_fixed));
-  parameter Boolean use_T_in = false
-    "Get the boundary temperature from the input connector"
-    annotation(Dialog(group="Boundary conditions"));
+    annotation (Dialog(group="Boundary conditions",enable=use_T_fixed));
+  parameter Modelica.Units.SI.Temperature T_in_nom=T_fixed
+    "Nominal boundary temperature, for calculation of design heat loss"
+    annotation (Dialog(group="Design power", tab="Advanced",enable=use_T_fixed or use_T_in));
   parameter Boolean use_Q_in = false
-    "Get the boundary heat flux from the input connector"
+    "Use a heat flow boundary condition which is read from the input connection Q_in"
     annotation(Dialog(group="Boundary conditions"));
-
+  parameter Modelica.Units.SI.HeatFlowRate Q_in_nom=0
+    "Nominal boundary heat flux, for calculation of design heat loss (positive if entering the wall)"
+    annotation (Dialog(group="Design power", tab="Advanced", enable=use_Q_in));
   Modelica.Blocks.Interfaces.RealInput T if use_T_in
     "Input for boundary temperature"                 annotation (Placement(
         transformation(extent={{-120,10},{-100,30}}),iconTransformation(extent={{-120,10},
             {-100,30}})));
   Modelica.Blocks.Interfaces.RealInput Q_flow if use_Q_in
-    "Input for boundary heat flow rate entering the wall" annotation (Placement(
+    "Input for boundary heat flow rate entering the wall (positive)" annotation (Placement(
         transformation(extent={{-120,-30},{-100,-10}}),
                                                     iconTransformation(extent={{-120,
             -30},{-100,-10}})));
@@ -70,6 +75,8 @@ protected
   IDEAS.Buildings.Components.Interfaces.WeaBus weaBus(final numSolBus=sim.numIncAndAziInBus,
       outputAngles=sim.outputAngles)                  "Weather bus"
     annotation (Placement(transformation(extent={{40,-80},{60,-60}})));
+initial equation
+    QTra_design=if use_T_in or use_T_fixed then U_value*A*(TRefZon - T_in_nom) else -Q_in_nom;
 equation
   assert(not (use_T_in and use_Q_in or use_T_in and use_T_fixed or use_Q_in and use_T_fixed),
     "In "+getInstanceName()+": Only one of the following options can be used simultaneously: use_T_in, use_Q_in, use_T_fixed");
@@ -137,11 +144,18 @@ to enable an input for a prescribed boundary condition temperature or heat flow
 Alternatively, parameters <code>use_T_fixed</code> and <code>T_fixed</code> can be used
 to specify a fixed boundary condition temperature.
 It is not allowed to enabled multiple of these three options. 
-If all are disabled then an adiabatic boundary (<code>Q_flow=0</code>) is used.
+If all are disabled, an adiabatic boundary (<code>Q_flow=0</code>) is used.</p>
+Parameters <code>T_in_nom</code> and <code>Q_in_nom</code> are used for the calculation 
+of heat losses, when the temperature boundary condition and heat flow boundary condition are applied, respectively.  
 </p>
 </html>", revisions = "<html>
 <ul>
 <li>
+November 7, 2024, by Anna Dell'Isola and Jelger Jansen:<br/>
+Update calculation of transmission design losses.
+See <a href=\"https://github.com/open-ideas/IDEAS/issues/1337\">#1337</a>
+</li>
+<li>
 Februari 18, 2024, by Filip Jorissen:<br/>
 Modifications for supporting trickle vents and interzonal airflow.
 </li>
diff --git a/IDEAS/Buildings/Components/Interfaces/DummyConnection.mo b/IDEAS/Buildings/Components/Interfaces/DummyConnection.mo
index 5730a22b51..b4659cc376 100644
--- a/IDEAS/Buildings/Components/Interfaces/DummyConnection.mo
+++ b/IDEAS/Buildings/Components/Interfaces/DummyConnection.mo
@@ -61,6 +61,9 @@ model DummyConnection "Source generator/sink for propsbus"
     Placement(visible = true, transformation(origin = {-42, -16}, extent = {{0, 80}, {20, 100}}, rotation = 0)));
   IDEAS.Fluid.Sources.Boundary_pT bou(redeclare package Medium= IDEAS.Media.Air, nPorts = 3) if isZone  annotation(
     Placement(visible = true, transformation(origin = {-30, 40}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
+  Modelica.Blocks.Sources.Constant TRefZon(k=T)      if isZone
+    annotation (Placement(transformation(extent={{-40,60},{-20,80}})));
+
 equation
   connect(prescribedHeatFlow[1].port, zoneBus.surfCon) annotation (Line(
       points={{-50,20},{62,20},{62,-1.9},{100.1,-1.9}},
@@ -147,12 +150,26 @@ equation
     Line(points = {{-20, 40}, {100, 40}, {100, -2}}, color = {255, 204, 51}));
   connect(bou.ports[1], zoneBus.port_1) annotation(
     Line(points = {{-20, 40}, {100, 40}, {100, -2}}, color = {255, 204, 51}));
-   annotation(
-    Diagram(coordinateSystem(preserveAspectRatio = false, extent = {{-100, -100}, {100, 100}})),
-    Icon(coordinateSystem(preserveAspectRatio = false, extent = {{-100, -100}, {100, 100}}), graphics = {Line(points = {{60, 60}, {-60, -60}}, color = {0, 0, 255}), Line(points = {{-60, 60}, {60, -60}}, color = {0, 0, 255})}),
-    Documentation(revisions = "<html>
+  connect(TRefZon.y, zoneBus.TRefZon) annotation (Line(points={{-19,70},{100.1,70},
+          {100.1,-1.9}}, color={0,0,127}));
+   annotation (Diagram(coordinateSystem(preserveAspectRatio=false, extent={{-100,
+            -100},{100,100}})),           Icon(coordinateSystem(
+          preserveAspectRatio=false, extent={{-100,-100},{100,100}}), graphics={
+          Line(
+          points={{60,60},{-60,-60}},
+          color={0,0,255},
+          smooth=Smooth.None), Line(
+          points={{-60,60},{60,-60}},
+          color={0,0,255},
+          smooth=Smooth.None)}),
+    Documentation(revisions="<html>
 <ul>
 <li>
+November 7, 2024, by Anna Dell'Isola and Jelger Jansen:<br/>
+Assign value for <code>TRefZon</code> in the bus connector.
+See <a href=\"https://github.com/open-ideas/IDEAS/issues/1337\">#1337</a>
+</li>
+<li>
 January 2, 2023, by Filip Jorissen:<br/>
 Added support for stack effect airflow.
 </li>
diff --git a/IDEAS/Buildings/Components/Interfaces/PartialSurface.mo b/IDEAS/Buildings/Components/Interfaces/PartialSurface.mo
index 677b21bb1c..fab853534d 100644
--- a/IDEAS/Buildings/Components/Interfaces/PartialSurface.mo
+++ b/IDEAS/Buildings/Components/Interfaces/PartialSurface.mo
@@ -26,11 +26,7 @@ partial model PartialSurface "Partial model for building envelope component"
     annotation (Dialog(group="Design power",tab="Advanced"));
   parameter Modelica.Units.SI.Temperature T_start=293.15
     "Start temperature for each of the layers"
-    annotation(Dialog(tab="Dynamics", group="Initial condition"));
-
-  parameter Modelica.Units.SI.Temperature TRef_a=291.15
-    "Reference temperature of zone on side of propsBus_a, for calculation of design heat loss"
-    annotation (Dialog(group="Design power",tab="Advanced"));
+	annotation (Dialog(tab="Dynamics", group="Initial condition"));
   parameter Boolean linIntCon_a=sim.linIntCon
     "= true, if convective heat transfer should be linearised"
     annotation (Dialog(tab="Convection"));
@@ -137,6 +133,9 @@ protected
   Modelica.Thermal.HeatTransfer.Sources.PrescribedHeatFlow prescribedHeatFlowQgai
     "Component for computing conservation of energy";
 
+  Modelica.Units.SI.Temperature TRefZon=propsBusInt.TRefZon
+      "Reference zone temperature for calculation of design heat load";
+
   IDEAS.Buildings.Components.Interfaces.ZoneBusVarMultiplicator gain(redeclare
       package Medium = Medium,                                       k=nWin)
     "Gain for all propsBus variable to represent nWin surfaces instead of 1"
@@ -269,6 +268,10 @@ equation
     Documentation(revisions="<html>
 <ul>
 <li>
+November 7, 2024, by Anna Dell'Isola and Jelger Jansen:<br/>
+Add variable <code>TRefZon</code> to be used when calculating <code>QTra_design</code>.
+See <a href=\"https://github.com/open-ideas/IDEAS/issues/1337\">#1337</a>
+</li>
 October 30, 2024, by Klaas De Jonge and Filip Jorissen:<br/>
 Additions for supporting interzonal airflow: use of crackoroperabledoor model, default column height implementation for stack-effect.
 </li>
diff --git a/IDEAS/Buildings/Components/Interfaces/PartialZone.mo b/IDEAS/Buildings/Components/Interfaces/PartialZone.mo
index d75cc69c1c..da2a024469 100644
--- a/IDEAS/Buildings/Components/Interfaces/PartialZone.mo
+++ b/IDEAS/Buildings/Components/Interfaces/PartialZone.mo
@@ -34,13 +34,16 @@ model PartialZone "Building zone model"
   parameter Boolean calculateViewFactor = false
     "Explicit calculation of view factors: works well only for rectangular zones!"
     annotation(Dialog(tab="Advanced", group="Radiative heat exchange"));
+  parameter Modelica.Units.SI.Temperature TZon_design=294.15
+    "Reference zone temperature for calculation of design heat load"
+    annotation (Dialog(group="Design heat load", tab="Advanced"));
   final parameter Modelica.Units.SI.Power QInf_design=1012*1.204*V/3600*n50_int
-      /n50toAch*(273.15 + 21 - sim.Tdes)
+      /n50toAch*(TZon_design - sim.Tdes)
     "Design heat losses from infiltration at reference outdoor temperature";
   final parameter Modelica.Units.SI.Power QRH_design=A*fRH
     "Additional power required to compensate for the effects of intermittent heating";
   final parameter Modelica.Units.SI.Power Q_design(fixed=false)
-    "Total design heat losses for the zone";
+    "Total design heat losses for the zone (including transmission, infiltration, and reheating; excluding ventilation)";
   parameter Medium.Temperature T_start=Medium.T_default
     "Start value of temperature"
     annotation(Dialog(tab = "Initialization"));
@@ -194,6 +197,9 @@ model PartialZone "Building zone model"
   Modelica.Blocks.Math.Add addCFlow[max(Medium.nC,1)](k2 = intGaiOcc.s_co2) "Add tracer mass flow rates"  annotation (
     Placement(visible = true, transformation(origin = {-6, 34}, extent = {{4, -4}, {-4, 4}}, rotation = 0)));
 protected
+  Modelica.Blocks.Sources.RealExpression TRefZon[nSurf](each y=TZon_design)
+    "Reference zone temperature for the surfaces connected to this zone, for calculation of design heat load";
+
   parameter Real n50_int(unit="1/h",min=0.01,fixed= false)
     "n50 value cfr airtightness, i.e. the ACH at a pressure diffence of 50 Pa"
     annotation(Dialog(enable=use_custom_n50,tab="Airflow", group="Airtightness"));
@@ -314,11 +320,11 @@ end Setq50;
 
 
 initial equation
-
-
   n50_int = if use_custom_n50 and not setq50.allSurfacesCustom then n50 else sum(propsBusInt.v50)/V;
 
-  Q_design=QInf_design+QRH_design+QTra_design; //Total design load for zone (additional ventilation losses are calculated in the ventilation system)
+  Q_design=QInf_design+QRH_design+QTra_design;
+  //Total design load for zone (excluding ventilation losses, these are assumed to be calculated in the ventilation system
+  //and should be added afterwards to obtain the total design heat load). See for example IDEAS.Templates.Interfaces.Building.
 
 equation
   if interzonalAirFlow.verifyBothPortsConnected then
@@ -545,8 +551,9 @@ end for;
     Line(points = {{-18, 26}, {-12, 26}, {-12, 10}, {110, 10}}, color = {0, 0, 127}));
   connect(addmWatFlow.u1, mWat_flow) annotation(
     Line(points = {{-2, 42}, {10, 42}, {10, -80}, {120, -80}}, color = {0, 0, 127}));
-  annotation (Placement(transformation(extent={{
-            140,48},{100,88}})),
+  connect(TRefZon.y, propsBusInt.TRefZon);
+
+  annotation (Placement(transformation(extent={{140,48},{100,88}})),
     Icon(coordinateSystem(preserveAspectRatio=false, extent={{-100,-100},{100,100}}),
          graphics),
     Documentation(info="<html>
@@ -559,6 +566,11 @@ Change Medium to IDEAS.Media.Air and use 'constrainedby' for Modelica.Media.Inte
 This is for <a href=https://github.com/open-ideas/IDEAS/issues/1375>#1375</a>.
 </li>
 <li>
+November 7, 2024, by Anna Dell'Isola and Jelger Jansen:<br/>
+Add parameter <code>TZon_design</code> to be used when calculating <code>Q_design</code>.
+See <a href=\"https://github.com/open-ideas/IDEAS/issues/1337\">#1337</a>
+</li>
+<li>
 October 30, 2024, by Klaas De Jonge:<br/>
 Modifications for interzonal airflow and stack-effect input. 
 </li>
diff --git a/IDEAS/Buildings/Components/Interfaces/ZoneBus.mo b/IDEAS/Buildings/Components/Interfaces/ZoneBus.mo
index 821c80ae26..aa4cc471c5 100644
--- a/IDEAS/Buildings/Components/Interfaces/ZoneBus.mo
+++ b/IDEAS/Buildings/Components/Interfaces/ZoneBus.mo
@@ -51,11 +51,12 @@ expandable connector ZoneBus
   IDEAS.Buildings.Components.Interfaces.RealConnector v50(final unit="m3/h") "v50 if the surface has a custome q50 value" annotation ();
   IDEAS.Buildings.Components.Interfaces.RealConnector q50_zone(final unit="m3/(h.m2)") "v50 of the surface" annotation ();
   IDEAS.Buildings.Components.Interfaces.BooleanConnector use_custom_q50 "true if custome q50 value is assigned to surface" annotation ();
-  IDEAS.Buildings.Components.Interfaces.BooleanConnector use_custom_n50 "true if the zone n50 is a custom value" annotation ();
-  IDEAS.Buildings.Components.Interfaces.RealConnector hzone(final unit="m") "Zone height: distance between floor and ceiling" annotation ();
-  IDEAS.Buildings.Components.Interfaces.RealConnector hfloor(final unit="m") "Absolute height of zone floor" annotation ();
-
-
+  IDEAS.Buildings.Components.Interfaces.BooleanConnector use_custom_n50 "true if the zone n50 is a custom value";
+  IDEAS.Buildings.Components.Interfaces.RealConnector hzone(final unit="m") "Zone height: distance between floor and ceiling";
+  IDEAS.Buildings.Components.Interfaces.RealConnector hfloor(final unit="m") "Absolute height of zone floor";
+  IDEAS.Buildings.Components.Interfaces.RealConnector TRefZon(
+    final quantity="Temperature",
+    final unit="K") "Reference zone temperature";
   annotation (Documentation(info="<html>
 <p>
 Connector that contains a weather bus and further
@@ -65,6 +66,11 @@ heat and information between a zone and a surface.
 </html>", revisions="<html>
 <ul>
 <li>
+November 7, 2024, by Anna Dell'Isola and Jelger Jansen:<br/>
+Add connector <code>TRefZon</code> to be used when calculating <code>QTra_design</code>.
+See <a href=\"https://github.com/open-ideas/IDEAS/issues/1337\">#1337</a>
+</li>
+<li>
 Februari 18, 2024, by Filip Jorissen:<br/>
 Modifications for supporting trickle vents and interzonal airflow.
 </li>
diff --git a/IDEAS/Buildings/Components/Interfaces/ZoneBusVarMultiplicator.mo b/IDEAS/Buildings/Components/Interfaces/ZoneBusVarMultiplicator.mo
index 3dd33be9fa..61b2492767 100644
--- a/IDEAS/Buildings/Components/Interfaces/ZoneBusVarMultiplicator.mo
+++ b/IDEAS/Buildings/Components/Interfaces/ZoneBusVarMultiplicator.mo
@@ -43,7 +43,7 @@ protected
       redeclare package Medium = Medium,final k=k) if sim.interZonalAirFlowType == IDEAS.BoundaryConditions.Types.InterZonalAirFlow.TwoPorts
     "Mass flow rate multiplier for port 3"
     annotation (Placement(transformation(origin = {0, -208}, extent = {{-10, -200}, {10, -180}})));
-  Modelica.Blocks.Math.Gain QTra_desgin(k=k) "Design heat flow rate"
+  Modelica.Blocks.Math.Gain QTra_design(k=k) "Design heat flow rate"
     annotation (Placement(transformation(extent={{-10,178},{10,198}})));
   Modelica.Blocks.Math.Gain area(k=k) "Heat exchange surface area"
     annotation (Placement(transformation(extent={{-10,150},{10,170}})));
@@ -87,10 +87,14 @@ protected
   Modelica.Blocks.Routing.RealPassThrough hFloor
     "Absolute height of the zone floor"
     annotation (Placement(transformation(extent={{8,-384},{-12,-364}})));
+  Modelica.Blocks.Routing.RealPassThrough TRefZon
+    "Reference zone temperature for calculation of design heat load"
+    annotation (Placement(transformation(extent={{8,-356},{-12,-336}})));
+
 equation
-  connect(QTra_desgin.u, propsBus_a.QTra_design) annotation (Line(points={{-12,188},
+  connect(QTra_design.u, propsBus_a.QTra_design) annotation (Line(points={{-12,188},
           {-100.1,188},{-100.1,0.1}},         color={0,0,127}));
-  connect(QTra_desgin.y, propsBus_b.QTra_design) annotation (Line(points={{11,188},
+  connect(QTra_design.y, propsBus_b.QTra_design) annotation (Line(points={{11,188},
           {100.1,188},{100.1,-0.1}},color={0,0,127}));
   connect(area.u, propsBus_a.area) annotation (Line(points={{-12,160},{-100.1,
           160},{-100.1,0.1}},color={0,0,127}));
@@ -181,6 +185,10 @@ equation
     Line(points = {{-10, -398}, {-100, -398}, {-100, 0}}, color = {0, 127, 255}));
   connect(massFlowRateMultiplier3.port_b, propsBus_b.port_3) annotation(
     Line(points = {{10, -398}, {100, -398}, {100, 0}}, color = {0, 127, 255}));
+  connect(TRefZon.u, propsBus_b.TRefZon) annotation (Line(points={{10,-346},{
+          100.1,-346},{100.1,-0.1}},  color={0,0,127}));
+  connect(TRefZon.y, propsBus_a.TRefZon) annotation (Line(points={{-13,-346},{
+          -100.1,-346},{-100.1,0.1}},  color={0,0,127}));
   annotation (Icon(coordinateSystem(preserveAspectRatio=false, extent={{-100,-180},
             {100,200}}), graphics={
         Polygon(
@@ -205,6 +213,11 @@ equation
     Documentation(revisions="<html>
 <ul>
 <li>
+November 7, 2024, by Anna Dell'Isola and Jelger Jansen:<br/>
+Add connector <code>TRefZon</code> to be used when calculating <code>QTra_design</code>.
+See <a href=\"https://github.com/open-ideas/IDEAS/issues/1337\">#1337</a>
+</li>
+<li>
 Februari 18, 2024, by Filip Jorissen:<br/>
 Modifications for supporting trickle vents and interzonal airflow.
 </li>
diff --git a/IDEAS/Buildings/Components/InternalWall.mo b/IDEAS/Buildings/Components/InternalWall.mo
index 55b8456c6c..d43ae43e3f 100644
--- a/IDEAS/Buildings/Components/InternalWall.mo
+++ b/IDEAS/Buildings/Components/InternalWall.mo
@@ -7,8 +7,9 @@ model InternalWall "interior opaque wall between two zones"
     final nWin=1,
     dT_nominal_a=1,
     E(y=if sim.computeConservationOfEnergy then layMul.E else 0),
-    Qgai(y=(if sim.openSystemConservationOfEnergy or not sim.computeConservationOfEnergy then 0 else sum(port_emb.Q_flow))),
-    final QTra_design = U_value*A*(TRef_a - TRef_b),
+    Qgai(y=(if sim.openSystemConservationOfEnergy or not sim.computeConservationOfEnergy
+           then 0 else sum(port_emb.Q_flow))),
+	final QTra_design(fixed=false),
     q50_zone(v50_surf = 0),
     crackOrOperableDoor(
       h_a1=-0.5*hzone_b + 0.75*hVertical + hRelSurfBot_b,
@@ -22,15 +23,16 @@ model InternalWall "interior opaque wall between two zones"
       hOpe=h,
       CDOpe=CD));
   //using custom q50 since this model is not an external component
-  parameter Boolean linIntCon_b = sim.linIntCon 
-    "= true, if convective heat transfer should be linearised" annotation(
-    Dialog(tab="Convection"));
-  parameter Modelica.Units.SI.TemperatureDifference dT_nominal_b = 1 
-    "Nominal temperature difference used for linearisation, negative temperatures indicate the solid is colder" annotation(
-    Dialog(tab="Convection"));
-  parameter Modelica.Units.SI.Temperature TRef_b = 291.15 
-    "Reference temperature of zone on side of propsBus_b, for calculation of design heat loss" annotation(
-    Dialog(group="Design power",tab="Advanced"));
+
+  parameter Boolean linIntCon_b=sim.linIntCon
+    "= true, if convective heat transfer should be linearised"
+    annotation(Dialog(tab="Convection"));
+  parameter Modelica.Units.SI.TemperatureDifference dT_nominal_b=1
+    "Nominal temperature difference used for linearisation, negative temperatures indicate the solid is colder"
+    annotation (Dialog(tab="Convection"));
+  Modelica.Units.SI.Temperature TRef_b = propsBus_b.TRefZon
+    "Reference temperature of zone on side of propsBus_b, for calculation of design heat loss";
+
   // open door modelling
   parameter Boolean hasCavity = false
     "=true, to model open door or cavity in wall"
@@ -113,10 +115,10 @@ protected
     final inc=incInt + Modelica.Constants.pi,
     final A=A)
     "convective surface heat transimission on the interior side of the wall"
-    annotation(
-    Placement(transformation(extent = {{-22, -10}, {-42, 10}})));
-  Modelica.Blocks.Sources.RealExpression QDesign_b(y = -QTra_design);
-  //Negative, because of its losses from zone side b to zone side a, oposite of calculation of QTra_design
+    annotation (Placement(transformation(extent={{-22,-10},{-42,10}})));
+  Modelica.Blocks.Sources.RealExpression QDesign_b(y=-QTra_design);
+  //Negative, because of its losses from zone side b to zone side a, opposite of calculation of QTra_design
+
   Modelica.Blocks.Sources.RealExpression incExp1(y=incInt + Modelica.Constants.pi)
     "Inclination angle";
   Modelica.Blocks.Sources.RealExpression aziExp1(y=aziInt + Modelica.Constants.pi)
@@ -139,12 +141,16 @@ protected
     dT=dT)
     if hasCavity and sim.interZonalAirFlowType <> IDEAS.BoundaryConditions.Types.InterZonalAirFlow.TwoPorts
     "Thermal-only model for open door"
-    annotation(
-    Placement(transformation(extent = {{-10, 30}, {10, 50}})));
+    annotation (Placement(transformation(extent={{-10,30},{10,50}})));
   final parameter Boolean useDooOpe = hasCavity and sim.interZonalAirFlowType == IDEAS.BoundaryConditions.Types.InterZonalAirFlow.TwoPorts;
+
 initial equation
   hzone_b = propsBus_b.hzone;
   hfloor_b = propsBus_b.hfloor;
+  QTra_design=U_value*A*(TRefZon - TRef_b)
+    "TRefZon is the reference temperature for heat loss calculations of the zone connected to propsbus_a,
+     TRef_b is the reference temperature for heat loss calculations of the zone connected to propsBus_b";
+
 equation
   connect(constOne.y, crackOrOperableDoor.y);
 //assert(IDEAS.Utilities.Math.Functions.isAngle(inc,0) and hAbs_floor_a>hfloor_b, getInstanceName()+ "is a ceiling, but the floor of the zone at probsbus_b lies above the floor of zone at probsbus_a, this is probably a mistake",level=AssertionLevel.warning);
@@ -192,10 +198,43 @@ equation
     Line(points = {{-40, -70}, {-52, -70}, {-52, 20}, {-100, 20}}, color = {0, 127, 255}));
   connect(boundary3_a.ports[1], propsBusInt.port_3) annotation(
     Line(points = {{40, -70}, {56, -70}, {56, 20}}, color = {0, 127, 255}));
-  annotation(
-    Icon(coordinateSystem(preserveAspectRatio = false, extent = {{-60, -100}, {60, 100}}), graphics = {Rectangle(fillColor = {255, 255, 255}, pattern = LinePattern.None, fillPattern = FillPattern.Solid, extent = {{-52, -90}, {48, -70}}), Rectangle(fillColor = {255, 255, 255}, pattern = LinePattern.None, fillPattern = FillPattern.Solid, extent = {{-50, 80}, {50, 100}}), Rectangle(fillColor = {175, 175, 175}, pattern = LinePattern.None, fillPattern = FillPattern.Backward, extent = {{-10, 80}, {10, -70}}), Line(points = {{-50, 80}, {50, 80}}, color = {175, 175, 175}), Line(points = {{-50, -70}, {50, -70}}, color = {175, 175, 175}), Line(points = {{-50, -90}, {50, -90}}, color = {175, 175, 175}), Line(points = {{-50, 100}, {50, 100}}, color = {175, 175, 175}), Line(points = {{-10, 80}, {-10, -70}}, thickness = 0.5), Line(points = {{10, 80}, {10, -70}}, thickness = 0.5)}),
-    Diagram(coordinateSystem(preserveAspectRatio = false, extent = {{-60, -100}, {60, 100}})),
-    Documentation(info = "<html>
+  annotation (
+    Icon(coordinateSystem(preserveAspectRatio=false,extent={{-60,-100},{60,100}}),
+        graphics={
+        Rectangle(
+          extent={{-52,-90},{48,-70}},
+          pattern=LinePattern.None,
+          lineColor={0,0,0},
+          fillColor={255,255,255},
+          fillPattern=FillPattern.Solid),
+        Rectangle(
+          extent={{-50,80},{50,100}},
+          pattern=LinePattern.None,
+          lineColor={0,0,0},
+          fillColor={255,255,255},
+          fillPattern=FillPattern.Solid),
+        Rectangle(
+          extent={{-10,80},{10,-70}},
+          fillColor={175,175,175},
+          fillPattern=FillPattern.Backward,
+          pattern=LinePattern.None),
+        Line(points={{-50,80},{50,80}}, color={175,175,175}),
+        Line(points={{-50,-70},{50,-70}}, color={175,175,175}),
+        Line(points={{-50,-90},{50,-90}}, color={175,175,175}),
+        Line(points={{-50,100},{50,100}}, color={175,175,175}),
+        Line(
+          points={{-10,80},{-10,-70}},
+          smooth=Smooth.None,
+          color={0,0,0},
+          thickness=0.5),
+        Line(
+          points={{10,80},{10,-70}},
+          smooth=Smooth.None,
+          color={0,0,0},
+          thickness=0.5)}),
+    Diagram(coordinateSystem(preserveAspectRatio=false,extent={{-60,-100},{60,
+            100}})),
+    Documentation(info="<html>
 <p>
 This is a wall model that should be used
 to simulate a wall or floor between two zones.
@@ -219,6 +258,11 @@ We assume that the value of <code>A</code> excludes the surface area of the cavi
 </html>", revisions = "<html>
 <ul>
 <li>
+November 7, 2024, by Anna Dell'Isola and Jelger Jansen:<br/>
+Update calculation of transmission design losses.
+See <a href=\"https://github.com/open-ideas/IDEAS/issues/1337\">#1337</a>
+</li>
+<li>
 October 30, 2024, by Klaas De Jonge:<br/>
 Modifications for stack-effect interzonal airflow heights.
 </li>
diff --git a/IDEAS/Buildings/Components/OuterWall.mo b/IDEAS/Buildings/Components/OuterWall.mo
index 950b41532a..fec84e9629 100644
--- a/IDEAS/Buildings/Components/OuterWall.mo
+++ b/IDEAS/Buildings/Components/OuterWall.mo
@@ -4,7 +4,7 @@ model OuterWall "Opaque building envelope construction"
      setArea(A=A),
      final nWin=1,
      dT_nominal_a=-3,
-     QTra_design(fixed=false));
+     final QTra_design(fixed=false));
 
   parameter Boolean linExtCon=sim.linExtCon
     "= true, if exterior convective heat transfer should be linearised (uses average wind speed)"
@@ -126,7 +126,7 @@ protected
     Placement(transformation(origin = {48, -4}, extent = {{-28, -76}, {-8, -56}})));
 
 initial equation
-  QTra_design =U_value*A*(273.15 + 21 - Tdes.y);
+  QTra_design =U_value*A*(TRefZon - Tdes.y);
 
 equation
   if hasBuildingShade then
@@ -304,6 +304,11 @@ The correct shading parameter values should then be passed through the redeclara
 </html>", revisions="<html>
 <ul>
 <li>
+November 7, 2024, by Anna Dell'Isola and Jelger Jansen:<br/>
+Update calculation of transmission design losses.
+See <a href=\"https://github.com/open-ideas/IDEAS/issues/1337\">#1337</a>
+</li>
+<li>
 October 30, 2024, by Klaas De Jonge:<br/>
 Modifications for stack-effect interzonal airflow heights and wind pressure profiles.
 </li>
diff --git a/IDEAS/Buildings/Components/SlabOnGround.mo b/IDEAS/Buildings/Components/SlabOnGround.mo
index 1f5eff64c2..857dbdddc7 100644
--- a/IDEAS/Buildings/Components/SlabOnGround.mo
+++ b/IDEAS/Buildings/Components/SlabOnGround.mo
@@ -4,7 +4,7 @@ model SlabOnGround "opaque floor on ground slab"
     custom_q50=0,
     final use_custom_q50=true,
     final nWin=1,
-    QTra_design=UEqui*A*(273.15 + 21 - sim.Tdes),
+    final QTra_design(fixed=false),
     add_door=false,
     dT_nominal_a=-3,
     inc=IDEAS.Types.Tilt.Floor,
@@ -36,7 +36,8 @@ model SlabOnGround "opaque floor on ground slab"
       cos(2*3.1415/12*(i - 1 + alfa)) + Lpe*dTeAvg*cos(2*3.1415/12*(i - 1 -
       beta)) for i in 1:12})/12 "Two-dimensional correction for edge flow";
 
-//Calculation of heat loss based on ISO 13370
+  Modelica.Blocks.Routing.RealPassThrough TdesGround "Design temperature passthrough";
+
   IDEAS.Fluid.Sources.MassFlowSource_T boundary1(
     redeclare package Medium = Medium,
     nPorts=1,
@@ -66,7 +67,7 @@ protected
   final parameter Real alfa=1.5 - 12/(2*3.14)*atan(dt/(dt + delta));
   final parameter Real beta=1.5 - 0.42*log(delta/(dt + 1));
   final parameter Real delta=sqrt(3.15*10^7*ground1.k/3.14/ground1.rho/ground1.c);
-  final parameter Real Lpi=A    *ground1.k/dt*sqrt(1/((1 + delta/dt)^2 + 1));
+  final parameter Real Lpi=A*ground1.k/dt*sqrt(1/((1 + delta/dt)^2 + 1));
   final parameter Real Lpe=0.37*PWall*ground1.k*log(delta/dt + 1);
   Real m = sim.solTim.y/3.1536e7*12 "time in months";
   final parameter Integer nLayGro = layGro.nLay "Number of ground layers";
@@ -103,9 +104,10 @@ protected
      "Boundary for bus a" annotation(
     Placement(transformation(origin = {0, -4}, extent = {{-28, -76}, {-8, -56}})));
 
-
+initial equation
+    QTra_design=UEqui*A*(TRefZon - weaBus.TGroundDes);
 equation
-
+  connect(TdesGround.u, weaBus.TGroundDes);
   connect(periodicFlow.port, layMul.port_b) annotation (Line(points={{-20,22},{
           -14,22},{-14,0},{-10,0}}, color={191,0,0}));
   connect(layGro.port_a, layMul.port_b)
@@ -191,6 +193,11 @@ zone that is surrounded by air at the ambient temperature.
 </html>", revisions="<html>
 <ul>
 <li>
+November 7, 2024, by Anna Dell'Isola and Jelger Jansen:<br/>
+Update calculation of transmission design losses.
+See <a href=\"https://github.com/open-ideas/IDEAS/issues/1337\">#1337</a>
+</li>
+<li>
 May 16, 2024, by Lucas Verleyen:<br>
 Created final and protected parameter <code>T_start_gro</code> for initial temperature of the ground (<code>layGro</code>).<br>
 See <a href=https://github.com/open-ideas/IDEAS/issues/1292>#1292</a> for more information.
diff --git a/IDEAS/Buildings/Components/Window.mo b/IDEAS/Buildings/Components/Window.mo
index f9d458d7db..6ff9334e52 100644
--- a/IDEAS/Buildings/Components/Window.mo
+++ b/IDEAS/Buildings/Components/Window.mo
@@ -12,7 +12,7 @@ model Window "Multipane window"
            A*(1 - frac),
            linearise=linIntCon_a or sim.linearise,
            dT_nominal=dT_nominal_a),
-    QTra_design(fixed=false),
+    final QTra_design(fixed=false),
     Qgai(y=if sim.computeConservationOfEnergy then
                                                   (gain.propsBus_a.surfCon.Q_flow +
         gain.propsBus_a.surfRad.Q_flow + gain.propsBus_a.iSolDif.Q_flow + gain.propsBus_a.iSolDir.Q_flow) else 0),
@@ -86,15 +86,12 @@ model Window "Multipane window"
   Modelica.Blocks.Interfaces.RealInput Ctrl if controlled
     "Control signal for screen between 0 and 1, 1 is fully closed" annotation (
       Placement(visible = true,transformation(
-        origin={-50,-120},extent={{20,-20},{-20,20}},
+        origin={-50,-110},extent={{20,-20},{-20,20}},
         rotation=-90), iconTransformation(
         origin={-40,-100},extent={{10,-10},{-10,10}},
         rotation=-90)));
 
-
-
-          replaceable parameter
-    IDEAS.Buildings.Data.WindPressureCoeff.Lowrise_Square_Exposed Cp_table
+  replaceable parameter IDEAS.Buildings.Data.WindPressureCoeff.Lowrise_Square_Exposed Cp_table
     constrainedby IDEAS.Buildings.Data.Interfaces.WindPressureCoeff
     "Tables with wind pressure coefficients for walls, floors and roofs"
     annotation (
@@ -273,7 +270,7 @@ protected
 
 
 initial equation
-  QTra_design = (U_value*A + fraType.briTyp.G) *(273.15 + 21 - Tdes.y);
+  QTra_design = (U_value*A + fraType.briTyp.G) *(TRefZon - Tdes.y);
   Habs =hAbs_floor_a + hRelSurfBot_a + (hVertical/2);
 
   assert(not use_trickle_vent or sim.interZonalAirFlowType <> IDEAS.BoundaryConditions.Types.InterZonalAirFlow.None,
@@ -360,7 +357,7 @@ equation
     Line(points={{-68.5,-32.7043},{-76,-32.7043},{-76,-62.2},{-79.4,-62.2}},
                                                                     color = {0, 0, 127}));
   connect(outsideAir.TDryBul_in, shaType.TDryBul) annotation (
-    Line(points={{-42,-80},{-46,-80},{-46,-49.4895},{-57.5,-49.4895}},
+    Line(points={{-42,-90},{-46,-90},{-46,-49.4895},{-57.5,-49.4895}},
                                                                     color = {0, 0, 127}));
   connect(trickleVent.y, y_trickleVent) annotation (
     Line(points={{36,-92},{36,-106},{30,-106},{30,-120}},
@@ -465,6 +462,11 @@ IDEAS.Buildings.Components.Validations.WindowEN673</a>
 </html>", revisions="<html>
 <ul>
 <li>
+November 7, 2024, by Anna Dell'Isola and Jelger Jansen:<br/>
+Update calculation of transmission design losses.
+See <a href=\"https://github.com/open-ideas/IDEAS/issues/1337\">#1337</a>
+</li>
+<li>
 October 30, 2024, by Klaas De Jonge:<br/>
 Modifications for stack-effect interzonal airflow heights and wind pressure profiles.
 </li>
diff --git a/IDEAS/Buildings/Components/Zone.mo b/IDEAS/Buildings/Components/Zone.mo
index ef1c990634..f1e707bfde 100644
--- a/IDEAS/Buildings/Components/Zone.mo
+++ b/IDEAS/Buildings/Components/Zone.mo
@@ -117,6 +117,13 @@ The model <code>ligCtr</code> determines how the lighting is controlled.
 See <a href=\"modelica://IDEAS.Buildings.Components.LightingControl\">
 IDEAS.Buildings.Components.LightingControl</a> for the available options.
 </p>
+<p>
+The design heat losses <code>Q_design</code> are calculated via an initial equation based on, but not exactly according to, NBN EN 12831-1 ANB:2020.
+This value includes heat losses via transmission (<code>QTra_design</code>) and infiltration (<code>QInf_design</code>) and accounts for reheating (<code>QRH_design</code>).
+Ventilation losses are not considered as this system is typically modelled in a seperate block, 
+see for example <a href=\"modelica://IDEAS.Templates.Interfaces.Building\"> IDEAS.Templates.Interfaces.Building</a>.
+In this model, the total design losses are calculated as the sum of the design losses from the building envelope (transmission, infiltration, reheating) and the ventilation system.
+</p>
 </html>", revisions="<html>
 <ul>
 <li>