feat(modelling): wire the HHR storage bundle into the candidate pool

recommend_heating joins the free candidate pool in _candidate_recommendations;
the HHR storage bundle reaches the optimised package for an electric/off-gas
dwelling. Catalogue + contingency (legacy 0.10) gain
high_heat_retention_storage_heaters; report.py _triggers_for explains the
heating trigger (electric/off-gas main); the harness _GENERATOR_MEASURE_TYPES
forcing test covers it. ASHP + boiler bundles still to come. ADR-0024.

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

domain/modelling/contingencies.py

@@ -18,6 +18,7 @@ _CONTINGENCY_RATES: dict[str, float] = {
     "double_glazing": 0.15,
     "secondary_glazing": 0.15,
     "low_energy_lighting": 0.26,
+    "high_heat_retention_storage_heaters": 0.10,
 }
 
 

harness/report.py

@@ -134,6 +134,16 @@ def _triggers_for(epc: EpcPropertyData, measure_type: str) -> dict[str, Any]:
                 epc.low_energy_fixed_lighting_bulbs_count
             ),
         }
+    if measure_type == "high_heat_retention_storage_heaters":
+        # heating_recommendation.py offers HHR storage to an electrically-heated
+        # or off-gas dwelling (translated from legacy is_high_heat_retention_valid).
+        return {
+            "main_fuel_type": epc.sap_heating.main_heating_details[0].main_fuel_type,
+            "sap_main_heating_code": (
+                epc.sap_heating.main_heating_details[0].sap_main_heating_code
+            ),
+            "mains_gas": epc.sap_energy_source.mains_gas,
+        }
     return {}
 
 

harness/sample_catalogue.json

@@ -10,5 +10,6 @@
   "internal_wall_insulation": { "unit_cost_per_m2": 90.0 },
   "double_glazing": { "unit_cost_per_m2": 600.0 },
   "secondary_glazing": { "unit_cost_per_m2": 510.0 },
-  "low_energy_lighting": { "unit_cost_per_m2": 8.0 }
+  "low_energy_lighting": { "unit_cost_per_m2": 8.0 },
+  "high_heat_retention_storage_heaters": { "unit_cost_per_m2": 3500.0 }
 }

orchestration/modelling_orchestrator.py

@@ -30,6 +30,7 @@ from domain.modelling.generators.wall_recommendation import recommend_cavity_wal
 from domain.modelling.generators.solid_wall_recommendation import recommend_solid_wall
 from domain.modelling.generators.glazing_recommendation import recommend_glazing
 from domain.modelling.generators.lighting_recommendation import recommend_lighting
+from domain.modelling.generators.heating_recommendation import recommend_heating
 from domain.geospatial.planning_restrictions import PlanningRestrictions
 from domain.sap10_calculator.calculator import SapCalculator
 from repositories.fuel_rates.fuel_rates_repository import FuelRatesRepository
@@ -209,6 +210,7 @@ def _candidate_recommendations(
         recommend_floor_insulation(effective_epc, products),
         recommend_glazing(effective_epc, products, planning_restrictions),
         recommend_lighting(effective_epc, products),
+        recommend_heating(effective_epc, products),
     )
     return [recommendation for recommendation in found if recommendation is not None]
 

tests/harness/test_console.py

@@ -34,6 +34,7 @@ _GENERATOR_MEASURE_TYPES = (
     "double_glazing",
     "secondary_glazing",
     "low_energy_lighting",
+    "high_heat_retention_storage_heaters",
 )
 
 
@@ -179,6 +180,28 @@ def test_run_modelling_recommends_low_energy_lighting_for_non_led_bulbs() -> Non
     assert "double_glazing" not in measure_types
 
 
+def _electric_storage_lit_epc() -> EpcPropertyData:
+    epc: EpcPropertyData = _build_uninsulated_cavity_and_floor_epc()
+    main = epc.sap_heating.main_heating_details[0]
+    main.main_fuel_type = 30
+    main.sap_main_heating_code = 402
+    main.main_heating_control = 2401
+    return epc
+
+
+def test_run_modelling_recommends_hhr_storage_for_an_electric_dwelling() -> None:
+    # Arrange — an electrically-heated dwelling on old storage heaters; the
+    # heating generator is wired into the candidate pool (ADR-0024).
+    epc: EpcPropertyData = _electric_storage_lit_epc()
+
+    # Act — Modelling only, no database.
+    plan = run_modelling(epc, goal_band="C", print_table=False)
+
+    # Assert — the HHR storage bundle reaches the optimised package.
+    measure_types = {measure.measure_type for measure in plan.measures}
+    assert "high_heat_retention_storage_heaters" in measure_types
+
+
 def test_sample_catalogue_prices_every_generator_measure_type() -> None:
     # Arrange — the default offline catalogue.
     products: ProductJsonRepository = ProductJsonRepository(DEFAULT_CATALOGUE)