diff --git a/IDEAS/Buildings/Components/Interfaces/PartialZone.mo b/IDEAS/Buildings/Components/Interfaces/PartialZone.mo
index b01afd5b2..fcd38bc3b 100644
--- a/IDEAS/Buildings/Components/Interfaces/PartialZone.mo
+++ b/IDEAS/Buildings/Components/Interfaces/PartialZone.mo
@@ -43,7 +43,7 @@ model PartialZone "Building zone model"
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"));
@@ -306,7 +306,9 @@ 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
diff --git a/IDEAS/Buildings/Components/Zone.mo b/IDEAS/Buildings/Components/Zone.mo
index ef1c99063..f1e707bfd 100644
--- a/IDEAS/Buildings/Components/Zone.mo
+++ b/IDEAS/Buildings/Components/Zone.mo
@@ -117,6 +117,13 @@ The model ligCtr determines how the lighting is controlled.
See
IDEAS.Buildings.Components.LightingControl for the available options.
+
+The design heat losses Q_design 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 (QTra_design) and infiltration (QInf_design) and accounts for reheating (QRH_design).
+Ventilation losses are not considered as this system is typically modelled in a seperate block,
+see for example IDEAS.Templates.Interfaces.Building.
+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.
+