feat(modelling): secondary-heating-removal generator + MeasureType (ADR-0028)

recommend_secondary_heating_removal offers one standalone Option that clears the
lodged secondary system. Eligibility is purely physical (offer iff
sap_heating.secondary_heating_type is set) — no effectiveness gate, since a
lodged secondary is a fixed emitter per RdSAP (portables are ignored), and the
electric-storage §A.2.2 no-op is the Optimiser's call (ADR-0028 decisions 1-2).
Priced at a flat per-dwelling decommission cost, not room-scaled.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

domain/modelling/generators/secondary_heating_recommendation.py

@@ -0,0 +1,57 @@
+"""The Secondary Heating Removal Recommendation Generator (ADR-0028).
+
+Offers to strip a dwelling's lodged secondary heating system so the main system
+serves 100% of space heating. A **standalone, co-selectable** Recommendation —
+not an Option in the Heating & Hot Water rec — because removing a secondary
+heater is independent of (and combinable with) a tune-up or boiler upgrade.
+
+Eligibility is purely physical: offered **iff a secondary is lodged**
+(`sap_heating.secondary_heating_type` is set). RdSAP only records a secondary
+when a *fixed* emitter is present (portable plug-in heaters are ignored), so a
+lodged secondary is by definition a fixed unit worth removing. There is no
+effectiveness gate — on an electric-storage main RdSAP §A.2.2 forces a default
+secondary back, making removal a no-op, but that is the Optimiser's call (it
+owns the economics), not eligibility's. Detection + pricing only; impact is
+produced later by scoring (ADR-0016).
+
+Priced at a flat per-dwelling decommission cost (one electrician visit to
+disconnect a fixed/hard-wired heater + localised making-good), not scaled by
+room count — the EPC lodges one secondary system with no heater count (ADR-0028).
+"""
+
+from typing import Final, Optional
+
+from datatypes.epc.domain.epc_property_data import EpcPropertyData
+from domain.modelling.measure_type import MeasureType
+from domain.modelling.recommendation import Cost, MeasureOption, Recommendation
+from domain.modelling.simulation import EpcSimulation, SecondaryHeatingOverlay
+from repositories.product.product_repository import ProductRepository
+
+_SECONDARY_HEATING_REMOVAL_MEASURE_TYPE: Final[MeasureType] = (
+    MeasureType.SECONDARY_HEATING_REMOVAL
+)
+
+
+def recommend_secondary_heating_removal(
+    epc: EpcPropertyData, products: ProductRepository
+) -> Optional[Recommendation]:
+    """Return a Secondary Heating Removal Recommendation — its single Option
+    clears the lodged secondary system — else None when no secondary is lodged
+    (nothing physical to remove)."""
+    if epc.sap_heating.secondary_heating_type is None:
+        return None
+
+    product = products.get(_SECONDARY_HEATING_REMOVAL_MEASURE_TYPE)
+    overlay = EpcSimulation(secondary_heating=SecondaryHeatingOverlay())
+    cost = Cost(
+        total=product.unit_cost_per_m2,
+        contingency_rate=product.contingency_rate,
+    )
+    option = MeasureOption(
+        measure_type=_SECONDARY_HEATING_REMOVAL_MEASURE_TYPE,
+        description="Remove the secondary heating system",
+        overlay=overlay,
+        cost=cost,
+        material_id=product.id,
+    )
+    return Recommendation(surface="Secondary Heating", options=(option,))

domain/modelling/measure_type.py

@@ -36,3 +36,4 @@ class MeasureType(StrEnum):
     SYSTEM_TUNE_UP = "system_tune_up"
     SYSTEM_TUNE_UP_ZONED = "system_tune_up_zoned"
     SOLAR_PV = "solar_pv"
+    SECONDARY_HEATING_REMOVAL = "secondary_heating_removal"

tests/domain/modelling/test_measure_type.py

@@ -30,6 +30,7 @@ _EXPECTED_VALUES = {
     "system_tune_up",
     "system_tune_up_zoned",
     "solar_pv",
+    "secondary_heating_removal",
 }
 
 

tests/domain/modelling/test_secondary_heating_recommendation.py

@@ -0,0 +1,94 @@
+"""Behaviour of the Secondary Heating Removal Recommendation Generator: offering
+to strip a dwelling's lodged secondary heating system so the main serves 100% of
+space heating (ADR-0028). A standalone, co-selectable Recommendation; eligibility
+is purely physical (offer iff a secondary is lodged) — the Optimiser de-selects
+the cases where removal cannot move SAP. Detection + pricing only (ADR-0016).
+"""
+
+import copy
+
+from datatypes.epc.domain.epc_property_data import EpcPropertyData
+from domain.modelling.generators.secondary_heating_recommendation import (
+    recommend_secondary_heating_removal,
+)
+from domain.modelling.product import Product
+from domain.modelling.recommendation import Recommendation
+from domain.modelling.simulation import SecondaryHeatingOverlay
+from repositories.product.product_repository import ProductRepository
+from tests.domain.sap10_calculator.worksheet._elmhurst_worksheet_000490 import (
+    build_epc,
+)
+
+
+class _StubProducts(ProductRepository):
+    """In-memory ProductRepository returning a fixed flat per-dwelling
+    decommission price (ADR-0028)."""
+
+    def get(self, measure_type: str) -> Product:
+        return Product(
+            measure_type=measure_type,
+            unit_cost_per_m2=250.0,
+            contingency_rate=0.25,
+            id=11,
+        )
+
+
+def _without_secondary(epc: EpcPropertyData) -> EpcPropertyData:
+    """Return a copy of `epc` with no secondary heating system lodged."""
+    clone: EpcPropertyData = copy.deepcopy(epc)
+    clone.sap_heating.secondary_heating_type = None
+    clone.sap_heating.secondary_fuel_type = None
+    return clone
+
+
+def test_dwelling_with_a_lodged_secondary_yields_a_removal_recommendation() -> None:
+    # Arrange — 000490 lodges a secondary system (SAP code 691, electric panel/
+    # convector/radiant heaters).
+    baseline: EpcPropertyData = build_epc()
+    assert baseline.sap_heating.secondary_heating_type == 691
+
+    # Act
+    recommendation: Recommendation | None = recommend_secondary_heating_removal(
+        baseline, _StubProducts()
+    )
+
+    # Assert — one Option whose overlay clears the secondary.
+    assert recommendation is not None
+    assert recommendation.surface == "Secondary Heating"
+    assert len(recommendation.options) == 1
+    option = recommendation.options[0]
+    assert option.measure_type == "secondary_heating_removal"
+    assert option.overlay.secondary_heating == SecondaryHeatingOverlay()
+
+
+def test_dwelling_without_a_secondary_yields_no_recommendation() -> None:
+    # Arrange — nothing lodged to remove (RdSAP only records a secondary when a
+    # fixed emitter is present; a portable would not be lodged at all).
+    baseline: EpcPropertyData = _without_secondary(build_epc())
+
+    # Act
+    recommendation: Recommendation | None = recommend_secondary_heating_removal(
+        baseline, _StubProducts()
+    )
+
+    # Assert
+    assert recommendation is None
+
+
+def test_recommendation_prices_a_flat_per_dwelling_decommission() -> None:
+    # Arrange — a lodged secondary; the cost is a flat per-dwelling decommission
+    # figure (one electrician visit + localised making-good), not room-scaled.
+    baseline: EpcPropertyData = build_epc()
+
+    # Act
+    recommendation: Recommendation | None = recommend_secondary_heating_removal(
+        baseline, _StubProducts()
+    )
+
+    # Assert
+    assert recommendation is not None
+    cost = recommendation.options[0].cost
+    assert cost is not None
+    assert cost.total == 250.0
+    assert cost.contingency_rate == 0.25
+    assert recommendation.options[0].material_id == 11