diff --git a/packages/domain/src/domain/sap/worksheet/tests/_elmhurst_worksheet_000474.py b/packages/domain/src/domain/sap/worksheet/tests/_elmhurst_worksheet_000474.py
index 8b2d8dbd..970cbf90 100644
--- a/packages/domain/src/domain/sap/worksheet/tests/_elmhurst_worksheet_000474.py
+++ b/packages/domain/src/domain/sap/worksheet/tests/_elmhurst_worksheet_000474.py
@@ -401,20 +401,41 @@ LINE_73_M_TOTAL_INTERNAL_GAINS_W: tuple[float, ...] = (
 # ============================================================================
 # §6 Solar gains — cert-derived inputs + expected outputs
 # ============================================================================
-# 5 wall windows across 2 glazing types (Manufacturer-declared g⊥):
-#   "Double between 2002" g=0.72: E 3.74, SE 0.50, NW 1.98
-#   "Double with unknown" g=0.76: E 3.74, NW 1.76
-# All PVC frame. No roof windows, no rooflights.
+# 7 wall windows mirroring the Summary §11 1:1, matching the Elmhurst
+# mapper's per-row extraction (mapper-vs-hand-built field-parity test).
+# Per-window curtain-transform U_eff sums to the same total as the prior
+# 5-window collapsed encoding (same total area per glazing-type group:
+# g=0.72/U=2.0 → 6.22 m² across 4 rows; g=0.76/U=2.8 → 5.50 m² across
+# 3 rows). Cascade output is unchanged at 1e-4.
+#
+# `window_location` carries the string bp identifier the Elmhurst mapper
+# surfaces ("Main", "1st Extension", "2nd Extension") — the per-bp
+# window apportionment in `heat_transmission_from_cert` (Slice 59)
+# routes via `_window_bp_index` which handles both the str and int
+# encodings; cohort 000474 has uniform wall U so the apportionment is
+# heat-loss-invariant.
 SECTION_6_VERTICAL_WINDOWS: tuple[SapWindow, ...] = (
-    # Windows 1 (PDF (27) U_eff=1.8519, raw U=2.0 post-2002 default; g_⊥=0.72):
-    # 3 entries, total area 6.22 m².
-    make_window(orientation=3, width=3.74, height=1.0, solar_transmittance=0.72, u_value=2.0),
-    make_window(orientation=4, width=0.50, height=1.0, solar_transmittance=0.72, u_value=2.0),
-    make_window(orientation=8, width=1.98, height=1.0, solar_transmittance=0.72, u_value=2.0),
-    # Windows 2 (PDF (27) U_eff=2.5180, raw U=2.8 pre-2002 default; g_⊥=0.76):
-    # 2 entries, total area 5.50 m². make_window default u_value=2.8 matches.
-    make_window(orientation=3, width=3.74, height=1.0, solar_transmittance=0.76),
-    make_window(orientation=8, width=1.76, height=1.0, solar_transmittance=0.76),
+    # Windows 1(Ext1) — NW
+    make_window(orientation=8, width=1.98, height=1.0, solar_transmittance=0.72,
+                u_value=2.0, window_location="1st Extension"),
+    # Windows 2(Ext1) — NW
+    make_window(orientation=8, width=1.76, height=1.0, solar_transmittance=0.76,
+                u_value=2.8, window_location="1st Extension"),
+    # Windows 3(Ext1) — E
+    make_window(orientation=3, width=1.98, height=1.0, solar_transmittance=0.72,
+                u_value=2.0, window_location="1st Extension"),
+    # Windows 3(Main) — E (0.50)
+    make_window(orientation=3, width=0.50, height=1.0, solar_transmittance=0.76,
+                u_value=2.8, window_location="Main"),
+    # Windows 3(Main) — E (1.76)
+    make_window(orientation=3, width=1.76, height=1.0, solar_transmittance=0.72,
+                u_value=2.0, window_location="Main"),
+    # Windows 3(Main) — SE (0.50)
+    make_window(orientation=4, width=0.50, height=1.0, solar_transmittance=0.72,
+                u_value=2.0, window_location="Main"),
+    # Windows 3(Ext2) — E
+    make_window(orientation=3, width=3.24, height=1.0, solar_transmittance=0.76,
+                u_value=2.8, window_location="2nd Extension"),
 )
 SECTION_6_ROOF_WINDOWS: tuple[RoofWindowInput, ...] = ()
 SECTION_6_ROOFLIGHTS: tuple[RooflightInput, ...] = ()