diff --git a/domain/epc/property_overlays/glazing_overlay.py b/domain/epc/property_overlays/glazing_overlay.py
index 9da7582d..6ee05030 100644
--- a/domain/epc/property_overlays/glazing_overlay.py
+++ b/domain/epc/property_overlays/glazing_overlay.py
@@ -14,10 +14,19 @@ from __future__ import annotations
 
 from typing import Optional
 
-from domain.modelling.simulation import EpcSimulation
+from domain.modelling.simulation import EpcSimulation, GlazingOverlay
+
+# Canonical glazing description → SAP10 glazing-type code (the Table 24 /
+# `u_window` cascade enum, `_GLAZING_CODE_TO_UWINDOW` in heat_transmission).
+_GLAZING_CODES: dict[str, int] = {
+    "Double glazing, 2002 or later": 2,
+}
 
 
 def glazing_overlay_for(
     glazing_value: str, building_part: int
 ) -> Optional[EpcSimulation]:
-    raise NotImplementedError
+    code = _GLAZING_CODES.get(glazing_value)
+    if code is None:
+        return None
+    return EpcSimulation(glazing=GlazingOverlay(glazing_type=code))