* Electric-immersion DHW: bill at 100%, not the space boiler's efficiency 🟩
A separate electric immersion heater (SAP water-heating code 903) is 100%
efficient (SAP 10.2 Table 4a) and the space-heating boiler provides no water
heating, so Appendix D2.1 Eq D1 (the boiler seasonal-efficiency cascade) must
not apply to it. But `_water_heating_main` resolves DHW to the SPACE main — a
gas/oil boiler keeps its PCDB record — so three water-efficiency branches in
cert_to_inputs billed the immersion-heated cylinder at the boiler's ~87% summer
efficiency (a mongrel: electric fuel price x gas-boiler efficiency):
1. the scalar `water_eff = water_pcdb_main.summer_efficiency_pct / 100`,
2. the SAP §9.4.11 / Table 4c(2) -5pp no-interlock adjustment, and
3. the Eq D1 (winter, summer) seasonal pair from `pcdb_main`.
Gate all three on `not dhw_is_electric_immersion`; the correct immersion path
(`_water_efficiency_with_category_inherit` -> 1.0, Eq D1 off) then applies,
mirroring the Table 3 zero-primary-loss gate already present for WHC 903.
General bug — fires for any WHC-903 dwelling whose space main is a PCDB gas/oil
boiler. It surfaced via the PasHub campaign's #1600 no-water-heating default
(WHC 999 -> 903) on a gas-combi dwelling: 58 Hackle St M11 4WU, SAP 55.30 ->
57.67 (pre_sap 58, verified 59).
Guardrails: the gov-API RdSAP corpus IMPROVES 78.8% -> 78.9% within-0.5, MAE
0.625 -> 0.622 (a handful of corpus certs with a boiler space main + electric
immersion move closer to accredited) — MAE ceiling ratcheted 0.626 -> 0.625.
Regression pinned in test_cert_to_inputs (RED before / GREEN after). pyright
0-new (cert_to_inputs baseline 30).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* PasHub SAP accuracy: thread low-energy lights + draught lobby (from_site_notes) 🟩
Two systematic silent-drops in the PAS Hub `from_site_notes` path, each a field
the gov-API/Elmhurst mappers thread but site-notes dropped, letting a favourable
default reach the SAP-10.2 calculator. Validated against the correct pashub
oracle (property_baseline_performance.effective_sap_score, portfolio 838):
cohort within-0.5 55.1% → 62.6%, MAE 0.599 → 0.521.
- Low-energy lights: when "exact LED/CFL known = No", PAS Hub lodges an aggregate
"Number of fixed low energy lights?" count. Previously dropped (no dataclass
field / extractor key / mapper thread) → calculator saw 0 low-energy bulbs and
applied the pessimistic L5b/L8c no-data default, under-rating SAP. Now threaded
into low_energy_fixed_lighting_bulbs_count, mirroring from_elmhurst_site_notes.
~6% of the cohort; resolves 58 Hackle (−0.43 vs oracle 59 with #1615).
- Draught lobby: _map_sap_ventilation set only the legacy `draught_lobby` field,
never the canonical `has_draught_lobby` §2 (13) gate the cascade reads, so the
surveyed lobby was ignored and infiltration over-stated. Now mirrors Elmhurst.
Two other audited levers were REJECTED against the pashub oracle (they matched
the gov-cert/RdSAP convention but pashub does not apply them): percent_draughtproofed
(cohort 30.8%) and the §A.2.2 assumed secondary heater (19.2%). A heat-network
control-code fix (2306→2303 for 16 Bingley) is HELD pending spec/Elmhurst
adjudication — it contradicts ADR-0053; see the NOTE on _PASHUB_HEAT_NETWORK_CONTROL_TO_SAP10.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* PasHub heat-network control: room-thermostat-only maps to 2308, not 2306 🟩
The Table 4e Group 3 label "charging linked to use of community heating, room
thermostat only" was mapped to 2306 — the linked-to-use *with-TRVs* code
(control type 3, space charging 1.00). The label explicitly excludes TRVs, so
it is control type 2 / space 1.05 = code 2308/2309 (linked-to-use → DHW 1.00).
2306 asserted TRVs the survey doesn't have and over-rated the cohort's sole
heat-network dwelling (16 Bingley Close 56.89 → 54.01 vs pashub oracle 52).
Verified against SAP 10.2 Table 4e as encoded in cert_to_inputs.py
(_CONTROL_TYPE_BY_CODE 2308→2, space-charging 2308→1.05, DHW 2308→1.00) and the
RdSAP control-label vocabulary in MainheatControlAttributes.py. 2303 (the earlier
audit's guess) is rejected: it is a flat-rate code (DHW 1.05) whose oracle match
was a coincidence of two offsetting spec violations. The residual +2.0 to oracle
52 is the documented SAP-10.2-engine-vs-lodged offset, not a fuel/flags gap
(those were threaded by the #1590 follow-up) — supersedes the ADR-0053 /
HANDOVER_838 "community fuel/flags" attribution.
16 Bingley is the only heat-network fixture in portfolio 838, so this moves one
fixture strictly toward its oracle. Harness ratcheted: within-0.5 0.51→0.58,
MAE 0.625→0.521 (observed 58.5% / 0.520 with all three 2026-07-15 levers).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* PasHub SAP accuracy: restore 3 dropped §2 infiltration inputs (from_site_notes)
`from_site_notes` uniquely dropped three ventilation inputs that the gov-API
and Elmhurst sibling mappers all set, causing a systematic cohort-wide SAP
under-rate vs the company's own accredited SAP-10.2 certs
(property_baseline_performance.effective_sap_score, portfolio 838):
1. percent_draughtproofed — never set, so §2(15) window infiltration was
pinned at its 0.25-ACH worst case on every dwelling. Reconstructed as the
area-weighted % of draught-proofed windows (mirrors Elmhurst
`draught_proofing_percent`). Dominant term.
2. Upper-storey +0.25 m joist void — omitted; now added, matching
`_UPPER_FLOOR_HEIGHT_ADD_M` on the gov-API/Elmhurst paths. This
RE-ADJUDICATES #1601 ("keep raw"): that call was confounded by the
then-present draught-proofing drop suppressing every verified dwelling.
3. sheltered_sides — left None → calculator's flat default of 2, which
over-shelters end/semi/detached (RdSAP §S5 = 1/1/0). Now derived from
built form.
The three are NON-ADDITIVE — each overshoots alone (which is why all three
were previously rejected individually) — but together they land all 7
verified ground-truth dwellings toward truth (none regress) and every built
form near zero. Cohort 62.1% -> 83.3% within-0.5, MAE 0.507 -> 0.377.
Guardrails: gov-API RdSAP corpus unchanged (78.9%, these are from_site_notes-
only helpers). pashub harness 58.5% -> 79.5% / MAE 0.520 -> 0.389; ratchets
tightened 0.58->0.78 and 0.521->0.40. pyright zero-new (mapper baseline 39).
New focused tests in TestFromSiteNotesInfiltrationFixes cover all three
fields incl. area-weighting and the built-form shelter map; goldens updated.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Resolve#1601 and land #1602/#1603 on the merged-#1609 tree, adjudicated
against Khalim's verified ground truth (not pre_sap).
#1601 (upper-floor +0.25 m joist void) — RESOLVED as keep-raw. The
gov-API/Elmhurst mappers add 0.25 m to upper-storey heights because their
lodged height is a clear internal ceiling. Against verified truth RAW beats
+0.25 on all 7 verified dwellings (16 Stillwater raw -0.35 within-band vs
+0.25 -0.75; every verified property is already under truth and +0.25 only
lowers SAP). pashub surveys internal dimensions (202/205 "Measurements
Location: Internal") and its upper-ground height gap is modal 0.00, so the
joist void is not differentially present and a blanket +0.25 is unsafe.
_map_floor_dimensions keeps the raw surveyed height with a RESOLVED note.
#1602 — semi-exposed / exposed floor exposure. The surveyed "Floor type"
"Semi Exposed (unheated)" now sets is_above_partially_heated_space (RdSAP
§5.14 U=0.7) and "Exposed Floor" sets is_exposed_floor (§5.13 Table 20), on
the lowest storey (floor==0) only, mirroring the gov-API/Elmhurst siblings.
New strict-raise _pashub_floor_exposure (ADR-0015).
#1603a — alternative walls. New AlternativeWall survey dataclass +
extract_alternative_walls (the "Alternative Wall"->"Windows" section) +
_map_pashub_alternative_walls -> sap_alternative_wall_1/2. The cascade
deducts each alt-wall area from the part's main opaque wall (no double
count), so a mixed-facade dwelling is billed at each sub-area's own
construction. The alt-wall block lodges "As Built" (capital B) — aliased to
the existing default insulation code.
#1603b — extension floor construction. ExtensionConstruction gains a floor
block (parsed like the main building) and _map_extension_building_part now
threads floor_type/construction/insulation/u_value_known, which the main
path already did and the extension silently dropped.
Cohort: within-0.5 50.2% -> 51.2%, MAE 0.652 -> 0.624, 0 strict-raise
errors across all 205. Verified-truth safe: none of the 7 verified
dwellings have alt walls, and #1602 moves the one it touches (2 Philips
exposed ext floor) by -0.00. pyright 0-new (mapper baseline 39). Goldens
test_full_building_construction + end_to_end EXTENSION_1 updated.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Three silent-drop extraction fixes the gov-API/Elmhurst mappers already apply
but `from_site_notes` uniquely omitted — each let a favorable default reach the
SAP-10.2 calculator and over-rate the dwelling. Same calculator, so the whole
gap was extraction fidelity (gov-API corpus 78.6% within-0.5 vs pashub 23.9%).
#1598 — electric-shower + bath counts: `_map_sap_heating` built `shower_outlets`
but never set `electric_shower_count`/`mixer_shower_count`/`number_baths`, so
the cascade defaulted to 1 gas mixer / 0 electric, billing electric-shower hot
water off the cheap main system. 100/205 fixtures lodge "Electric Shower".
#1599 — floor label: pashub lodges "Ground Floor" (capital F); the calculator's
RdSAP §5(12) suspended-timber floor-infiltration gate is case-sensitive on
"Ground floor", so the 0.2-ACH term was silently dropped. Normalized at the
mapper boundary. 98/205 suspended-timber.
#1600 — water-heating "None": the RdSAP 10 §10.7 "no water heating system"
signal was discarded and HW inherited the gas combi (58 Hackle 67.7 vs
verified 59). Coded to WHC 999 so the existing electric-immersion + Table
28/29 default fires (also folds in #1594: blank cylinder size is no cylinder,
not a phantom one).
Guinness GMCA 205 cohort: within-0.5 23.9% -> 50.2% (103/205), MAE 1.410 ->
0.650. Ratchets tightened to 0.50 / 0.65. Verified vs Khalim's ground truth
(16 Stillwater 78.2 -> 75.7 vs 76). #1601 (upper-floor +0.25 m) held — it
empirically over-corrects this cohort (internal-vs-external dimension question,
under investigation). pyright: 0 new errors.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Second sanctioned exception to "ratchets never loosen" — needs @KhalimCK's
call, since the prior note expected to re-tighten here. Exactly one cohort
property is WHC 950 (16 Bingley Close, +5.946 -> +6.818 = the whole +0.0043);
within-0.5 unchanged at 23.9%. Its pre_sap is verified correct but its ~+6
residual is a known extraction bug, and this hybrid gauge cannot adjudicate a
calculator fix (#1592 Problem 2). The gov-API corpus, which gauges the
calculator alone, improves.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Enumerates the 3 corpus certs that can move (all WHC 950) individually per
#1592 sub-task D: two improve (one crossing inside 0.5), one worsens and is
handed to sub-task C for an accredited oracle. No loosening required.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
pytest.approx is untyped under pyright strict, so the new assertions added
3 errors against the repo's zero-new-errors bar. Switches to the abs(...)
<= tol form already dominant in this file. No behaviour change.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
SAP 10.2 Table 3 ("For heat networks apply the formula above with p = 1.0
and h = 3 for all months") and §4.3's "insulated pipework" literal both
scope on the DHW source, so a water-only network gets the same row as a
network space main. Was falling back to the RdSAP §3 age-band default —
band E → p=0, h=5 — billing 64.58 kWh in January against the spec's 23.26.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
SAP 10.2 §4.3 (p.24) scopes itself to "where hot water is provided by a
heat network" and requires the Table 3 primary loss, so the gate keys on
the DHW source. Checked off the WHC before the main-keyed branches so a
non-boiler space main (cert 9093's warm air) can't zero it out.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
950 boilers / 951 CHP / 952 community heat pump differ only in plant
efficiency, which SAP 10.2 §4.3 puts in the Table 12 heat price — so the
dwelling's delivered-heat demand must not vary with it. Passes on the
previous commit's expression; verified RED against the prior impl, where
951 leaked 0.80/0.75 and 952 under-billed its DHW fuel by 3.15×.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
SAP 10.2 §4.3 (p.24) puts the water-heating efficiency in the Table 12
heat price, and C4 (p.53) scopes the plant efficiency to CO2/PE only, so
worksheet (310) = (64) × (305a) × (306) carries no efficiency term. The
dwelling-side divisor was applying it a second time.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Read stored lodged EPCs whatever refetch_epc says, so a stored assessment
can win the ADR-0001 Recency Tie-Break against the gov register.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Backs out the WHC-950/951/952 primary-loss (d3c0b9e4) and flat-rate-charging
(fecf4f62) changes to cert_to_inputs.py: they fire on ANY cert with those
water-heating codes, regressing the gov-API RdSAP corpus
(test_api_path_sap_accuracy_on_rdsap_21_0_1_corpus MAE 0.627 -> 0.630), and an
Opus audit found the water-only branch has a pre-existing plant-efficiency
double count they flow more kWh through. The calculator work + the correct
fix (water_eff = 1.0/(DLF*1.05)) + an Elmhurst-worksheet regression are
tracked in #1592, isolated from the extractor accuracy PR. The cylinder-
insulation MAPPER fix (f5e4814b) is retained.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Khalim-authorised MAE loosening: coding window orientation exposes the known
SAP-10.2-vs-lodged offset the zeroed solar gains were masking; within-0.5 is
the north-star metric and jumps 20.0% -> 23.9%.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
