Slice S0380.131: flip Table 32 heating-oil price 7.64 → 5.44 (empirical)

The published RdSAP 10 Specification 10-06-2025 PDF Table 32 (p.95) lists heating oil at 7.64 p/kWh. Two independent operational sources both use 5.44 p/kWh for the same fuel: - Elmhurst P960 worksheets across all five oil-fired variants in `sap worksheets/heating systems examples/` (oil 1, oil pcdb 1/2/3, pcdb 1) lodge 5.4400 p/kWh on (240) "Space heating - main system 1" and (247) "Water heating (other fuel)" for every "FuelType: Heating oil" worksheet. - The gov.uk EPC register's lodging software back-solves to ~5.48 p/kWh from cert 0240-0200-5706-2365-8010's lodged SAP 73 (oil + PV detached, age J). With heating-oil at 5.44 in the cascade this cert closes to ΔSAP = 0 exactly against its lodged value. The BRE technical papers (`docs/specs/sap10 technical papers/`) carry no Table 32 errata or fuel-price update, so the change is grounded in empirical cross-source evidence rather than a spec citation — the worksheet PDF is the source of truth per the project convention. Post-flip residuals: Heating-systems corpus (cascade − worksheet ΔSAP_c): oil 1 −9.7030 → +2.6578 oil pcdb 1 −11.6343 → +0.4239 ← within 1 SAP of closure oil pcdb 2 −11.6343 → +0.4239 oil pcdb 3 −10.8674 → +1.1597 pcdb 1 −9.4083 → +6.9521 ← largest remaining oil-cohort gap Golden fixtures (cascade − lodged SAP): 0240-0200-5706-2365-8010 resid −10 → +0 ← EXACT closure 0390-2954-3640-2196-4175 resid −6 → +7 ← oil-price bug was masking +13 SAP of opposite-direction cascade gaps; now exposed for follow-up PE / CO2 residuals are unaffected by the unit-price flip (cost-only change). The 41-variant corpus regression guard (S0380.129) holds; all other golden cohorts pass unchanged. Extended handover suite: 874 pass. Bio-FAME (code 73) shows the inverse divergence on oil 3/4 worksheets (worksheet 7.64 vs spec 5.44 — possible row-swap typo in the spec PDF) but flipping it has no measurable cascade effect today, so deferred until a cert that exercises it surfaces. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-06-08 11:17:27 +00:00 · 2026-05-31 09:21:29 +00:00 · 2026-05-31 09:21:29 +00:00 · 14eee259b4
commit 14eee259b4
parent 38e6d18a13
3 changed files with 51 additions and 14 deletions
--- a/backend/documents_parser/tests/test_heating_systems_corpus.py
+++ b/backend/documents_parser/tests/test_heating_systems_corpus.py
@ -76,6 +76,12 @@ class _CorpusExpectation:
 # fixtures cascade-execute; the residuals below are the current
 # cascade-vs-worksheet diff per variant. Closures land by re-pinning
 # the smaller expected residual.
+#
+# Slice S0380.131 re-pinned the 5 heating-oil variants (oil 1, oil pcdb
+# 1/2/3, pcdb 1) after `tables/table_32.py` flipped the heating-oil unit
+# price from RdSAP 10 Table 32's published 7.64 p/kWh to the Elmhurst-
+# worksheet-canonical 5.44 p/kWh. Worst-residual oil ΔSAP −11.63 → +0.42;
+# pcdb 1 −9.41 → +6.95 (largest remaining oil-cohort gap).
 _EXPECTATIONS: tuple[_CorpusExpectation, ...] = (
    _CorpusExpectation(variant='ashp', block='11a', expected_sap_resid=+5.6680, expected_cost_resid_gbp=-130.5995, expected_co2_resid_kg=-1.4283, expected_pe_resid_kwh=+1467.8983),
    _CorpusExpectation(variant='community heating 1', block='11b', expected_sap_resid=+4.1830, expected_cost_resid_gbp=-96.3816, expected_co2_resid_kg=-786.6453, expected_pe_resid_kwh=-940.7364),
@ -97,16 +103,16 @@ _EXPECTATIONS: tuple[_CorpusExpectation, ...] = (
    _CorpusExpectation(variant='electric 9', block='11a', expected_sap_resid=+12.0340, expected_cost_resid_gbp=-277.2813, expected_co2_resid_kg=-255.6076, expected_pe_resid_kwh=+362.4518),
    _CorpusExpectation(variant='gshp', block='11a', expected_sap_resid=+5.1598, expected_cost_resid_gbp=-118.8901, expected_co2_resid_kg=-41.4461, expected_pe_resid_kwh=+639.1890),
    _CorpusExpectation(variant='no system', block='11a', expected_sap_resid=+21.9350, expected_cost_resid_gbp=-505.4134, expected_co2_resid_kg=+689.2188, expected_pe_resid_kwh=-2454.8193),
-    _CorpusExpectation(variant='oil 1', block='11a', expected_sap_resid=-9.7030, expected_cost_resid_gbp=+223.5710, expected_co2_resid_kg=-242.2677, expected_pe_resid_kwh=+1259.6587),
+    _CorpusExpectation(variant='oil 1', block='11a', expected_sap_resid=+2.6578, expected_cost_resid_gbp=-61.2402, expected_co2_resid_kg=-242.2677, expected_pe_resid_kwh=+1259.6587),
    _CorpusExpectation(variant='oil 2', block='11a', expected_sap_resid=+26.0712, expected_cost_resid_gbp=-600.7179, expected_co2_resid_kg=+2230.1071, expected_pe_resid_kwh=+801.2920),
    _CorpusExpectation(variant='oil 3', block='11a', expected_sap_resid=+30.9500, expected_cost_resid_gbp=-712.1785, expected_co2_resid_kg=+2859.5796, expected_pe_resid_kwh=+738.4592),
    _CorpusExpectation(variant='oil 4', block='11a', expected_sap_resid=+28.5927, expected_cost_resid_gbp=-655.6129, expected_co2_resid_kg=+2636.9526, expected_pe_resid_kwh=+701.8340),
    _CorpusExpectation(variant='oil 5', block='11a', expected_sap_resid=+120.7457, expected_cost_resid_gbp=-6312.0020, expected_co2_resid_kg=+1345.3630, expected_pe_resid_kwh=-2780.6222),
    _CorpusExpectation(variant='oil 6', block='11a', expected_sap_resid=+24.4087, expected_cost_resid_gbp=-561.8886, expected_co2_resid_kg=-658.8928, expected_pe_resid_kwh=-478.5733),
-    _CorpusExpectation(variant='oil pcdb 1', block='11a', expected_sap_resid=-11.6343, expected_cost_resid_gbp=+268.0722, expected_co2_resid_kg=-35.9551, expected_pe_resid_kwh=+2086.7505),
-    _CorpusExpectation(variant='oil pcdb 2', block='11a', expected_sap_resid=-11.6343, expected_cost_resid_gbp=+268.0722, expected_co2_resid_kg=-35.9551, expected_pe_resid_kwh=+2086.7505),
-    _CorpusExpectation(variant='oil pcdb 3', block='11a', expected_sap_resid=-10.8674, expected_cost_resid_gbp=+250.4014, expected_co2_resid_kg=-53.1709, expected_pe_resid_kwh=+1897.4341),
-    _CorpusExpectation(variant='pcdb 1', block='11a', expected_sap_resid=-9.4083, expected_cost_resid_gbp=+228.9812, expected_co2_resid_kg=-845.8065, expected_pe_resid_kwh=-171.6971),
+    _CorpusExpectation(variant='oil pcdb 1', block='11a', expected_sap_resid=+0.4239, expected_cost_resid_gbp=-9.7668, expected_co2_resid_kg=-35.9551, expected_pe_resid_kwh=+2086.7505),
+    _CorpusExpectation(variant='oil pcdb 2', block='11a', expected_sap_resid=+0.4239, expected_cost_resid_gbp=-9.7668, expected_co2_resid_kg=-35.9551, expected_pe_resid_kwh=+2086.7505),
+    _CorpusExpectation(variant='oil pcdb 3', block='11a', expected_sap_resid=+1.1597, expected_cost_resid_gbp=-26.7204, expected_co2_resid_kg=-53.1709, expected_pe_resid_kwh=+1897.4341),
+    _CorpusExpectation(variant='pcdb 1', block='11a', expected_sap_resid=+6.9521, expected_cost_resid_gbp=-157.6055, expected_co2_resid_kg=-845.8065, expected_pe_resid_kwh=-171.6971),
    _CorpusExpectation(variant='pcdb 3', block='11a', expected_sap_resid=+27.7563, expected_cost_resid_gbp=-637.0435, expected_co2_resid_kg=-446.3815, expected_pe_resid_kwh=+2097.4553),
    _CorpusExpectation(variant='solid fuel 10', block='11a', expected_sap_resid=+14.7769, expected_cost_resid_gbp=-340.4814, expected_co2_resid_kg=+1906.2620, expected_pe_resid_kwh=-584.5284),
    _CorpusExpectation(variant='solid fuel 11', block='11a', expected_sap_resid=+8.4098, expected_cost_resid_gbp=-193.7739, expected_co2_resid_kg=+2262.3481, expected_pe_resid_kwh=+2583.7764),
--- a/domain/sap10_calculator/rdsap/tests/test_golden_fixtures.py
+++ b/domain/sap10_calculator/rdsap/tests/test_golden_fixtures.py
@ -74,7 +74,7 @@ _EXPECTATIONS: tuple[_GoldenExpectation, ...] = (
    _GoldenExpectation(
        cert_number="0240-0200-5706-2365-8010",
        actual_sap=73,
-        expected_sap_resid=-10,
+        expected_sap_resid=+0,
        expected_pe_resid_kwh_per_m2=+0.0542,
        expected_co2_resid_tonnes_per_yr=+0.0626,
        notes=(
@ -88,9 +88,11 @@ _EXPECTATIONS: tuple[_GoldenExpectation, ...] = (
            "(total HLC 221.6 W/K). Slice 97 added glazing_type=2 "
            "(RdSAP 10 Table 24 DG England/Wales 2002+, U=2.0, g=0.72) — "
            "PE residual +17.85 → +15.69 and CO2 +1.01 → +0.90. SAP "
-            "residual still -15: the residual sits in subsystems other than "
-            "the windows lookup (PV cascade, RR description-implied "
-            "insulation nuance, possibly oil-tariff secondary)."
+            "residual was -10 throughout the Slice 97..130 range; "
+            "Slice S0380.131 flipped table_32.py heating-oil price 7.64 → "
+            "5.44 per Elmhurst worksheet evidence + this cert's gov.uk "
+            "back-solve, closing SAP residual -10 → +0 exactly. PE / CO2 "
+            "residuals are unaffected by the unit-price flip."
        ),
    ),
    _GoldenExpectation(
@ -124,7 +126,7 @@ _EXPECTATIONS: tuple[_GoldenExpectation, ...] = (
    _GoldenExpectation(
        cert_number="0390-2954-3640-2196-4175",
        actual_sap=60,
-        expected_sap_resid=-6,
+        expected_sap_resid=+7,
        expected_pe_resid_kwh_per_m2=-26.3749,
        expected_co2_resid_tonnes_per_yr=-2.5544,
        notes=(
@ -136,9 +138,14 @@ _EXPECTATIONS: tuple[_GoldenExpectation, ...] = (
            "(_separately_timed_dhw=True when cylinder lodged per "
            "SAP 10.2 Table 2b note b) + RdSAP §3 default) closed a "
            "10% storage-loss over-count via TF 0.60 → 0.54, lifting SAP "
-            "53 → 54 (resid -7 → -6). Remaining -6 traces to fabric heat-"
-            "loss / oil-fuel cost cascade (oil tariff + age-F masonry on "
-            "a 360 m² detached typically lands -5..-10 SAP)."
+            "53 → 54 (resid -7 → -6). Slice S0380.131 flipped heating-oil "
+            "tariff 7.64 → 5.44 (cert 0240 closed exactly), exposing this "
+            "cert's previously-masked +13 SAP of cascade gaps: residual "
+            "swung -6 → +7. The oil-price bug was netting against an "
+            "opposite-direction gap (cert lodges age F + 360 m² detached "
+            "+ Firebird PCDF — likely fabric or hot-water cascade). PE / "
+            "CO2 residuals unchanged by the unit-price flip; remaining "
+            "SAP residual is a follow-up slice candidate."
        ),
    ),
    _GoldenExpectation(
--- a/domain/sap10_calculator/tables/table_32.py
+++ b/domain/sap10_calculator/tables/table_32.py
@ -8,6 +8,9 @@ targets RdSAP10 cost per ADR-0010 amendment.
 CO2 emission factors and primary energy factors are unchanged from
 SAP10.2 Table 12 (RdSAP10 §19.2), so they continue to live in
 `domain.sap10_calculator.tables.table_12` rather than being duplicated here.
+
+Heating-oil (code 4) is a documented divergence from the published spec
+PDF — see the note on the dict entry below.
 """

 from __future__ import annotations
@ -31,7 +34,28 @@ UNIT_PRICE_P_PER_KWH: Final[dict[int, float]] = {
    9: 3.48,    # LPG SC11F
    7: 7.60,    # biogas (including anaerobic digestion)
    # Liquid fuels
-    4: 7.64,    # heating oil
+    #
+    # Slice S0380.131 — heating oil (code 4): operationally-canonical
+    # 5.44 p/kWh, not the 7.64 published in the RdSAP 10 Specification
+    # 10-06-2025 PDF Table 32 (p.95). The spec PDF value is the outlier;
+    # two independent implementations agree on 5.44:
+    #   - Elmhurst P960 worksheets (fuel cost row, line ref (240) "Space
+    #     heating - main system 1") for variants oil 1, oil pcdb 1/2/3,
+    #     pcdb 1 in `sap worksheets/heating systems examples/` — every
+    #     "FuelType: Heating oil" worksheet lodges 5.4400 p/kWh.
+    #   - The gov.uk EPC register's lodging software back-solves to
+    #     ~5.48 p/kWh from cert 0240-0200-5706-2365-8010's lodged SAP
+    #     73 (an oil + PV detached at age J), and with 5.44 in the
+    #     cascade this cert closes to ΔSAP = 0 exactly against its
+    #     lodged value.
+    # BRE technical papers (`docs/specs/sap10 technical papers/`) carry
+    # no Table 32 errata or fuel-price update, so the change is grounded
+    # in empirical cross-source evidence rather than a spec citation.
+    # FAME (code 73) shows the inverse pattern on oil 3/4 worksheets
+    # (worksheet 7.64 vs spec 5.44) but flipping it has no measurable
+    # cascade effect today — deferred until a cert that exercises it
+    # surfaces.
+    4: 5.44,    # heating oil — see comment above (Slice S0380.131)
    71: 7.64,   # bio-liquid HVO
    73: 5.44,   # bio-liquid FAME
    75: 6.10,   # B30K