Calculation updates

assets/js/physics.js

@@ -239,8 +239,13 @@ export function calcManagedIndoorTempPass(TaArr, globArr, elevArr, buildingType
 //     so it adds to ambient cabin temp, not direct radiant load.
 //     Above 60° the sun mostly hits the roof; below 10° it reflects.
 //
-//  Wind is ignored (vehicle is sealed). No evaporative cooling.
-//  Steady-state reached after ~45–60 min of parking.
+//  Wind is ignored unless ventilation is enabled. No evaporative cooling.
+//  Cars warm quickly; motorhomes and caravans are treated as insulated living
+//  spaces with 25–35 mm sandwich panels, so panel heat gain is much smaller
+//  and the interior response is slower than a car cabin. Because they are
+//  occupied living spaces, they also retain warmth from previous hours, people,
+//  appliances, and background heating; without that, cool sunny days are
+//  under-estimated badly.
 //
 // Colour thresholds in the table:
 //   < 35 °C  — warm but tolerable for short periods
@@ -259,8 +264,9 @@ export function calcVehicleInteriorTemp(Ta, globalRad, solElev, vehicleType = 'c
   // hOut ~10 W/m²K (light breeze over panel surface even when parked)
   const hOut = 10;
   const panelSurfaceTemp = Ta + panelAbsorbed / hOut;
-  // Conductive gain into cabin: panel-to-cabin air, ~4 W/m²K through metal + trim
-  const hCabin = 4;
+  // Conductive gain into cabin. Cars are thin metal + trim; motorhomes and
+  // caravans use insulated sandwich panels, so their bodyU is much lower.
+  const hCabin = preset.bodyU ?? 4;
   const conductionGain = hCabin * (panelSurfaceTemp - Ta); // W/m²
 
   // ── 2. Side-window glazing gain (angle-dependent) ─────────────────
@@ -285,12 +291,24 @@ export function calcVehicleInteriorTemp(Ta, globalRad, solElev, vehicleType = 'c
   // ── Combine into cabin air temperature ───────────────────────────
   // Total heat input per m² of cabin surface
   const totalGain = conductionGain + glazingGain;
-  // Cabin heat loss: varies by vehicle type (motorhomes insulated, cars not).
-  // With windows open, convective loss is roughly 5× higher — air moves freely
+  // Cabin heat rejection: an effective blend of leakage, internal air volume,
+  // and surfaces exchanging heat with the outside. With windows open it is
+  // roughly 5× higher — air moves freely
   // through the cabin, flushing heat out and capping interior temperature much
   // closer to ambient. Cabin temp still rises a little due to panel/roof solar gain.
   const effectiveHLoss = ventilated ? preset.hCabinLoss * 5 : preset.hCabinLoss;
-  const Ti = Ta + totalGain / effectiveHLoss;
+  const thermalMass = preset.thermalMass ?? 1;
+  const solarRise = (totalGain / effectiveHLoss) * thermalMass;
+
+  // Motorhomes/caravans behave more like small insulated rooms than parked
+  // cars. This term captures retained living-space warmth: strongest on cool
+  // days, tapering away as outdoor air warms, and reduced when ventilated.
+  const retainedWarmth = preset.retainedWarmth
+    ? Math.max(0, 8 - 0.25 * Ta) * (ventilated ? 0.35 : 1)
+    : 0;
+  const internalGain = (preset.internalGain ?? 0) * (ventilated ? 0.35 : 1);
+
+  const Ti = Ta + solarRise + retainedWarmth + internalGain;
 
   // Clamp: can't be cooler than outside air; physical cap at 90 °C
   return Math.max(Ta, Math.min(Ti, 90));