Map full-SAP energy source, mains-gas inference and lighting bulbs 🟩

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

datatypes/epc/domain/mapper.py

@@ -688,9 +688,17 @@ class EpcPropertyDataMapper:
             door_count=door_count,
             insulated_door_count=door_count,
             insulated_door_u_value=insulated_door_u,
+            # D5: lighting outlet counts → bulb counts (full SAP lodges total +
+            # low-energy outlet counts, like the RdSAP 17.1 path).
             cfl_fixed_lighting_bulbs_count=0,
             led_fixed_lighting_bulbs_count=0,
-            incandescent_fixed_lighting_bulbs_count=0,
+            incandescent_fixed_lighting_bulbs_count=(
+                (schema.sap_energy_source.fixed_lighting_outlets_count or 0)
+                - (schema.sap_energy_source.low_energy_fixed_lighting_outlets_count or 0)
+            ),
+            low_energy_fixed_lighting_bulbs_count=(
+                schema.sap_energy_source.low_energy_fixed_lighting_outlets_count or 0
+            ),
             # D4: full SAP lodges the measured U as text in the element
             # description ("Average thermal transmittance X W/m²K"); carry it
             # through so u_wall/u_floor/u_roof parse it instead of re-deriving
@@ -714,14 +722,18 @@ class EpcPropertyDataMapper:
             # the domain SapHeating the calculator consumes (PCDB efficiency via
             # main_heating_index_number; water cascade via water_heating_code).
             sap_heating=_sap_17_1_heating(schema),
+            # D5: mains_gas derived from the heating fuel (full SAP has no
+            # explicit flag); tariff → meter_type; wind turbines pass through.
             sap_energy_source=SapEnergySource(
-                mains_gas=False,
-                meter_type="",
+                mains_gas=_sap_dwelling_on_mains_gas(schema),
+                meter_type=str(schema.sap_energy_source.electricity_tariff or ""),
                 pv_battery_count=0,
-                wind_turbines_count=0,
+                wind_turbines_count=schema.sap_energy_source.wind_turbines_count or 0,
                 gas_smart_meter_present=False,
                 is_dwelling_export_capable=False,
-                wind_turbines_terrain_type="",
+                wind_turbines_terrain_type=str(
+                    schema.sap_energy_source.wind_turbine_terrain_type or ""
+                ),
                 electricity_smart_meter_present=False,
             ),
         )
@@ -2504,6 +2516,19 @@ _SAP_LIVING_AREA_FRACTION_BY_ROOMS: Final[Dict[int, float]] = {
 }
 
 
+# SAP main_fuel_type code for mains gas.
+_SAP_MAINS_GAS_FUEL_CODE: Final[int] = 1
+
+
+def _sap_dwelling_on_mains_gas(schema: SapSchema17_1) -> bool:
+    """D5: full SAP has no explicit mains-gas flag — infer it from whether any
+    main-heating system burns mains gas (fuel code 1)."""
+    return any(
+        d.main_fuel_type == _SAP_MAINS_GAS_FUEL_CODE
+        for d in schema.sap_heating.main_heating_details
+    )
+
+
 def _sap_17_1_heating(schema: SapSchema17_1) -> SapHeating:
     """D6: map full-SAP `sap_heating` onto the domain `SapHeating`. Field names
     differ from RdSAP — `is_flue_fan_present`→`fan_flue_present`,

datatypes/epc/domain/tests/test_from_sap_schema.py

@@ -232,6 +232,28 @@ class TestFromSapSchema17_1LivingArea:
         assert self._map("sap_17_1_flat.json").habitable_rooms_count == 3
 
 
+class TestFromSapSchema17_1EnergySource:
+    """Slice D5: full-SAP sap_energy_source → mains_gas (derived from heating
+    fuel), lighting outlet counts → bulb counts, and the tariff/meter."""
+
+    @pytest.fixture
+    def sample(self) -> EpcPropertyData:
+        schema = from_dict(SapSchema17_1, load("sap_17_1.json"))
+        return EpcPropertyDataMapper.from_sap_schema_17_1(schema)
+
+    def test_mains_gas_derived_from_heating_fuel(self, sample: EpcPropertyData) -> None:
+        # Main heating fuel is mains gas (code 1) → mains_gas True.
+        assert sample.sap_energy_source.mains_gas is True
+
+    def test_lighting_outlet_counts_to_bulbs(self, sample: EpcPropertyData) -> None:
+        # 1 fixed outlet, 1 low-energy → 1 low-energy bulb, 0 incandescent.
+        assert sample.low_energy_fixed_lighting_bulbs_count == 1
+        assert sample.incandescent_fixed_lighting_bulbs_count == 0
+
+    def test_wind_turbine_fields_pass_through(self, sample: EpcPropertyData) -> None:
+        assert sample.sap_energy_source.wind_turbines_count == 0
+
+
 class TestFromSapSchema17_1Heating:
     """Slice D6: full-SAP sap_heating (differing field names) maps onto the
     domain SapHeating + MainHeatingDetail the calculator consumes."""

datatypes/epc/schema/sap_schema_17_1.py

@@ -88,6 +88,19 @@ class SapBuildingPart:
     building_part_number: Optional[int] = None
 
 
+@dataclass
+class SapEnergySource:
+    """Electricity tariff, on-site generation and lighting. Lighting outlet
+    counts map to the engine's bulb counts; `mains_gas` is derived from the
+    heating fuel (full SAP has no explicit flag)."""
+
+    electricity_tariff: Optional[int] = None
+    wind_turbines_count: Optional[int] = None
+    wind_turbine_terrain_type: Optional[int] = None
+    fixed_lighting_outlets_count: Optional[int] = None
+    low_energy_fixed_lighting_outlets_count: Optional[int] = None
+
+
 @dataclass
 class SapMainHeatingDetail:
     """One main-heating system. Field names differ from RdSAP (e.g.
@@ -157,6 +170,7 @@ class SapSchema17_1:
     sap_opening_types: List[SapOpeningType]
     sap_building_parts: List[SapBuildingPart]
     sap_heating: SapHeating
+    sap_energy_source: SapEnergySource = field(default_factory=SapEnergySource)
     # measured living-room area (m²); the engine consumes it via a back-solved
     # habitable_rooms_count (Table 27). Optional — 100% present in the corpus.
     living_area: Optional[Union[int, float]] = None