diff --git a/repositories/epc/epc_postgres_repository.py b/repositories/epc/epc_postgres_repository.py
index 3f4e09b1..60383fd1 100644
--- a/repositories/epc/epc_postgres_repository.py
+++ b/repositories/epc/epc_postgres_repository.py
@@ -582,6 +582,12 @@ class EpcPostgresRepository(EpcRepository):
                 else None
             ),
             multiple_glazed_proportion=p.multiple_glazed_proportion,
+            # Top-level mirror of sap_ventilation.extract_fans_count (the mapper
+            # sets both from the same source). The deterministic calculator reads
+            # the sap_ventilation copy, not this one; reconstruct it from the same
+            # column anyway so EpcPropertyData round-trips complete, with no
+            # allow-list exception for a field that trivially mirrors a persisted one.
+            extract_fans_count=p.ventilation_extract_fans_count,
             calculation_software_version=p.calculation_software_version,
             mechanical_vent_duct_placement=p.mechanical_vent_duct_placement,
             mechanical_vent_duct_insulation=p.mechanical_vent_duct_insulation,
diff --git a/tests/repositories/epc/test_epc_persistence_field_coverage.py b/tests/repositories/epc/test_epc_persistence_field_coverage.py
index 6f9481d8..4f0c8faa 100644
--- a/tests/repositories/epc/test_epc_persistence_field_coverage.py
+++ b/tests/repositories/epc/test_epc_persistence_field_coverage.py
@@ -35,10 +35,6 @@ from repositories.epc.epc_postgres_repository import EpcPostgresRepository
 # ``ClassName.field`` (a single field) or ``ClassName`` (the whole dataclass is
 # an un-persisted, tracked gap awaiting its FE columns / child table).
 _UNPERSISTED_ALLOWLIST: dict[str, str] = {
-    # Redundant top-level field: the calculator reads
-    # `sap_ventilation.extract_fans_count` (which round-trips via
-    # `_to_ventilation`), never this top-level duplicate.
-    "EpcPropertyData.extract_fans_count": "redundant; scoring uses sap_ventilation.extract_fans_count",
     # Not read by the calculator (dormant); no DB column yet.
     "EpcPropertyData.air_tightness": "dormant — not read by the calculator; no FE column",
     "EpcPropertyData.lzc_energy_sources": "dormant — not read by the calculator; no FE column",