Slice S0380.126: resolve Elmhurst bare "Underfloor Heating" via RdSAP 10 §10.11

Elmhurst Summary §14.0 Main Heating1 sometimes lodges the bare form
"Heat Emitter: Underfloor Heating" without a subtype qualifier (in
screed / timber floor). The mapper's `_ELMHURST_HEAT_EMITTER_TO_SAP10`
dict only carried the qualified forms, so the bare lodging fell through
to None and was passed as a raw string into `MainHeatingDetail.heat_
emitter_type` — causing `_responsiveness` to strict-raise
`UnmappedSapCode` on every cert with this lodging (2 variants on the
heating-systems corpus: `electric 1` + `oil 6`).

Per RdSAP 10 Specification §10.11 Table 29 page 56 ("Heating and hot
water parameters"):

  > "Underfloor heating: If dwelling has a ground floor, then according
  >  to the floor construction (see Table 19 if unknown):
  >    - solid, main property age band A to E: concrete slab
  >    - solid, main property age band F to M: in screed
  >    - suspended timber: in timber floor
  >    - suspended, not timber: in screed
  >  Otherwise (i.e. upper floor flats), take floor as suspended"

New helper `_resolve_elmhurst_underfloor_subtype` keys off the main BP's
`floor.floor_type` + `construction_age_band` and returns:

  - SAP10.2 Table 4d emitter code 2 (in screed) → R=0.75 — for
    solid + age F-M, suspended-not-timber, and upper-floor-flat cases
  - SAP10.2 Table 4d emitter code 3 (timber floor) → R=1.0 — for
    suspended-timber

The solid + age A-E "concrete slab" branch (R=0.25) has no cert-side
enum entry yet, so the helper strict-raises `UnmappedElmhurstLabel`
when that combination lands — the next variant lodging an A-E solid
underfloor will surface the gap loudly per
[[reference-unmapped-sap-code]].

Property 001431 (the heating-systems corpus dwelling) lodges §9.0
"Type: S Solid" + §3.0 "Date Built: G 1983-1990" (age band G ∈ F-M)
→ "in screed" → code 2 → R=0.75. Both `electric 1` and `oil 6` now
cascade-execute (corpus tally 32 → 34 OK / 41 populated).

Extended handover suite at HEAD post-slice: **830 pass, 0 fail**
(was 829 + 1 new AAA test).

Pyright net-zero on touched files (45 → 45 — pre-existing errors
unrelated).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/documents_parser/tests/test_summary_pdf_mapper_chain.py

@@ -236,6 +236,44 @@ def test_summary_001479_mapper_extensions_count_matches_extension_bps() -> None:
     assert len(epc.sap_building_parts) == 3
 
 
+def test_summary_001431_electric_1_underfloor_heating_resolves_to_in_screed_per_rdsap_10_section_10_11() -> None:
+    # Arrange — Heating-systems corpus fixture 001431 / "electric 1" lodges
+    # §14.0 "Heat Emitter: Underfloor Heating" (bare form, no subtype
+    # qualifier). Per RdSAP 10 Specification §10.11 Table 29 page 56
+    # ("Heating and hot water parameters"):
+    #
+    #   "Underfloor heating: If dwelling has a ground floor, then
+    #    according to the floor construction (see Table 19 if unknown):
+    #      - solid, main property age band A to E: concrete slab
+    #      - solid, main property age band F to M: in screed
+    #      - suspended timber: in timber floor
+    #      - suspended, not timber: in screed"
+    #
+    # Property 001431 lodges §9.0 Floors as "Type: S Solid" + §3.0 Date
+    # Built "G 1983-1990" (age band G ∈ F-M), so the spec rule resolves
+    # to "in screed" → SAP10.2 Table 4d emitter enum 2 (R=0.75).
+    #
+    # Pre-slice the Elmhurst mapper passed the raw "Underfloor Heating"
+    # string through `_elmhurst_heat_emitter_int`'s `dict.get` (which
+    # returned None for the bare lodging) and then through to the
+    # MainHeatingDetail's `heat_emitter_type` field, which made the
+    # cascade strict-raise at `_responsiveness` for any of the 2
+    # corpus variants lodging this form (`electric 1` + `oil 6`).
+    summary_pdf = (
+        Path(__file__).parents[3]
+        / "sap worksheets/heating systems examples/electric 1/Summary_001431.pdf"
+    )
+    pages = _summary_pdf_to_textract_style_pages(summary_pdf)
+    site_notes = ElmhurstSiteNotesExtractor(pages).extract()
+
+    # Act
+    epc = EpcPropertyDataMapper.from_elmhurst_site_notes(site_notes)
+
+    # Assert
+    main_1 = epc.sap_heating.main_heating_details[0]
+    assert main_1.heat_emitter_type == 2
+
+
 def test_summary_001479_main_party_wall_construction_is_cavity_unfilled() -> None:
     # Arrange — cert 001479 Main §7 Walls lodges "Party Wall Type: CU
     # Cavity masonry unfilled". The Elmhurst leading-code map previously

datatypes/epc/domain/mapper.py

@@ -3836,8 +3836,78 @@ def _elmhurst_main_fuel_int(fuel_type: str) -> Optional[int]:
     return _ELMHURST_MAIN_FUEL_TO_SAP10.get(fuel_type)
 
 
-def _elmhurst_heat_emitter_int(emitter: str) -> Optional[int]:
-    return _ELMHURST_HEAT_EMITTER_TO_SAP10.get(emitter)
+def _resolve_elmhurst_underfloor_subtype(
+    main_floor: ElmhurstFloorDetails,
+    main_age_band: str,
+) -> int:
+    """RdSAP 10 Specification §10.11 Table 29 page 56 — derive the
+    underfloor-heating subtype from the main BP's floor construction +
+    age band when the Elmhurst Summary §14.0 lodges the bare
+    "Underfloor Heating" lodging form (no subtype qualifier).
+
+    Spec rule verbatim:
+
+      "Underfloor heating: If dwelling has a ground floor, then according
+       to the floor construction (see Table 19 if unknown):
+         - solid, main property age band A to E: concrete slab
+         - solid, main property age band F to M: in screed
+         - suspended timber: in timber floor
+         - suspended, not timber: in screed
+       Otherwise (i.e. upper floor flats), take floor as suspended"
+
+    Returns the SAP10.2 Table 4d emitter int code:
+      2 = Underfloor (in screed above insulation) → R=0.75
+      3 = Underfloor (timber floor)               → R=1.0
+
+    The "concrete slab" branch (R=0.25 per Table 4d) has no cert-side
+    enum entry yet — strict-raise per [[reference-unmapped-sap-code]]
+    so a future age A-E + solid + underfloor fixture surfaces the gap
+    loudly instead of silently routing through `in screed`.
+    """
+    floor_type = main_floor.floor_type
+    age_letter = main_age_band[0] if main_age_band else ""
+    is_solid = floor_type.startswith("S Solid") or floor_type == "Solid"
+    is_suspended_timber = (
+        floor_type.startswith("T Suspended timber")
+        or floor_type == "Suspended timber"
+    )
+    is_suspended_not_timber = (
+        floor_type.startswith("N Suspended, not timber")
+        or floor_type == "Suspended, not timber"
+    )
+    if is_solid:
+        if age_letter in {"A", "B", "C", "D", "E"}:
+            raise UnmappedElmhurstLabel(
+                "main_heating.heat_emitter",
+                (
+                    f"Underfloor heating on solid floor + age band "
+                    f"{main_age_band!r} resolves to 'concrete slab' per "
+                    f"RdSAP 10 §10.11 Table 29 (p.56) — SAP10.2 Table 4d "
+                    f"R=0.25 — but no cert-side enum entry exists yet"
+                ),
+            )
+        return 2  # solid + F-M → in screed
+    if is_suspended_timber:
+        return 3  # suspended timber → in timber floor
+    if is_suspended_not_timber:
+        return 2  # suspended not timber → in screed
+    # Upper-floor flat (no ground floor) → "take floor as suspended"
+    # → in screed per spec (defaults to suspended-not-timber side).
+    return 2
+
+
+def _elmhurst_heat_emitter_int(
+    emitter: str,
+    main_floor: Optional[ElmhurstFloorDetails] = None,
+    main_age_band: Optional[str] = None,
+) -> Optional[int]:
+    if emitter in _ELMHURST_HEAT_EMITTER_TO_SAP10:
+        return _ELMHURST_HEAT_EMITTER_TO_SAP10[emitter]
+    # RdSAP 10 §10.11 Table 29 (p.56): bare "Underfloor heating" lodging
+    # derives subtype from main floor construction + age band.
+    if emitter == "Underfloor Heating" and main_floor is not None and main_age_band is not None:
+        return _resolve_elmhurst_underfloor_subtype(main_floor, main_age_band)
+    return None
 
 
 # Elmhurst boiler flue-type strings → SAP10 integer codes. Codes mirror
@@ -4294,7 +4364,11 @@ def _map_elmhurst_sap_heating(survey: ElmhurstSiteNotes) -> SapHeating:
         and mh.main_heating_sap_code in _ELECTRIC_SAP_MAIN_HEATING_CODES
     ):
         main_fuel_int = _STANDARD_ELECTRICITY_FUEL_CODE
-    heat_emitter_int = _elmhurst_heat_emitter_int(mh.heat_emitter)
+    heat_emitter_int = _elmhurst_heat_emitter_int(
+        mh.heat_emitter,
+        main_floor=survey.floor,
+        main_age_band=survey.construction_age_band,
+    )
     sap_control_int = _elmhurst_sap_control_code(sap_control)
     main_heating_category = _elmhurst_main_heating_category(mh, pcdb_index)
     # Strict-raise mirror of [[unmapped-api-code]] — when Main 1 has