diff --git a/datatypes/epc/domain/tests/test_from_sap_schema.py b/datatypes/epc/domain/tests/test_from_sap_schema.py
index 2153b3f5..47b6cc8c 100644
--- a/datatypes/epc/domain/tests/test_from_sap_schema.py
+++ b/datatypes/epc/domain/tests/test_from_sap_schema.py
@@ -800,3 +800,20 @@ class TestFullSapSchema16xNoFloorDimensions:
 
         # Act / Assert
         assert len(main_part.sap_floor_dimensions) == 1
+
+    def test_synthesised_floor_dimension_total_area(self, epc: EpcPropertyData) -> None:
+        # Arrange
+        fd = epc.sap_building_parts[0].sap_floor_dimensions[0]
+
+        # Act / Assert
+        assert fd.total_floor_area_m2 == 72.0
+
+    def test_synthesised_floor_dimension_heat_loss_perimeter(
+        self, epc: EpcPropertyData
+    ) -> None:
+        # Arrange: both sap_walls are wall_type=2 (exposed): 43.2 + 3.88 = 47.08 m².
+        # total_height falls back to 1.0 (no storey heights lodged), so perimeter = 47.08 m.
+        fd = epc.sap_building_parts[0].sap_floor_dimensions[0]
+
+        # Act / Assert
+        assert fd.heat_loss_perimeter_m == pytest.approx(47.08)