From cf131a4414616c82def6ffb2979a3fdfcc2e7256 Mon Sep 17 00:00:00 2001
From: DamonHD <d@hd.org>
Date: Fri, 22 Sep 2023 12:27:14 +0100
Subject: [PATCH] Extending ifHeatLossPerA2Storey().

---
 .../hg/HGTRVHPMModelParameterised.java        | 24 ++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/javasrc/org/hd/d/TRVmodel/hg/HGTRVHPMModelParameterised.java b/javasrc/org/hd/d/TRVmodel/hg/HGTRVHPMModelParameterised.java
index 7acae2b..d7c0498 100644
--- a/javasrc/org/hd/d/TRVmodel/hg/HGTRVHPMModelParameterised.java
+++ b/javasrc/org/hd/d/TRVmodel/hg/HGTRVHPMModelParameterised.java
@@ -252,9 +252,31 @@ private static double iwHeatLossPerA(final ModelParameters params)
      * This is only for a 2-storey detached, so in an ABAB arrangement (with BABA below)
      * each A room will lose each <em>either</em> to a B room below or above (not both).
      * Heat loss in each direction (up or down) is treated as the same.
+     * <p>
+     * Assumes that A room is at 'normal' temperature and B room is at setback temperature.
+     *
+     * @param params  model parameters; non-null
      */
 	private static double ifHeatLossPerA2Storey(final ModelParameters params)
 		{
+		return(ifHeatLossPerA2Storey(params, HGTRVHPMModel.NORMAL_ROOM_TEMPERATURE_C));
+		}
+
+    /**Internal floor/ceiling heat loss/transfer per A room (W) for 2-storey detached.
+     * Only applies when a B room is directly above or below.
+     * <p>
+     * This is only for a 2-storey detached, so in an ABAB arrangement (with BABA below)
+     * each A room will lose each <em>either</em> to a B room below or above (not both).
+     * Heat loss in each direction (up or down) is treated as the same.
+     *
+     * @param params  model parameters; non-null
+     * @param tempA  temperature of A room, must be no lower than B room setback.
+     */
+	private static double ifHeatLossPerA2Storey(final ModelParameters params, final double tempA)
+		{
+		if(!Double.isFinite(tempA)) { throw new IllegalArgumentException(); }
+		if(tempA < HGTRVHPMModel.SETBACK_ROOM_TEMPERATURE_C) { throw new IllegalArgumentException("A must not be colder than B"); }
+
 		if(!params.roomsAlternatingABAB) { return(0); }
 
     	// IFAabHL: internal floor/ceiling heat loss per Kelvin (W/K).
@@ -264,7 +286,7 @@ private static double ifHeatLossPerA2Storey(final ModelParameters params)
         // IFAabHLW: internal floor/ceiling heat loss per A room (W).
         final double IFAabHLW =
     		IFAabHL *
-    			(HGTRVHPMModel.NORMAL_ROOM_TEMPERATURE_C - HGTRVHPMModel.SETBACK_ROOM_TEMPERATURE_C);
+    			(tempA - HGTRVHPMModel.SETBACK_ROOM_TEMPERATURE_C);
 
 		return(IFAabHLW);
 		}