A flat roof lodged "Flat, no insulation" / "Flat, limited insulation" with
an undetermined insulation thickness ('ND'/'AB' → parsed None) was given the
Table 16 row-0/12mm U (2.30 / 1.50) from the description marker, regardless
of age band. Per RdSAP 10 §5.11.4 (PDF p.44) "U-values in Table 18 are used
when thickness of insulation cannot be determined" — the column (3)
flat-roof age-band default applies. The "no/limited insulation" text is
RdSAP's as-built rendering: at old bands (A-D) the column (3) default IS
2.30 (so those certs are unchanged), but a newer-band flat roof carries the
age-band insulation as built (band H = 0.35, F = 0.68, not 2.30).
Confirmed by the description-vs-rating audit: cert 0390-2753 (top-floor
flat, band H, "Flat, no insulation", thickness 'ND') lodges roof
energy_efficiency_rating = 3 (moderate U), NOT the rating-1 that 2.30
implies — and drove a -31.78 SAP error (roof 202 W/K over 88 m²). Same
masked-at-old-bands structure as the cavity-U fix: accurate at A-D where the
default coincides with 2.30, catastrophic only where it diverges.
Pitched roofs are deliberately NOT rerouted (their "no insulation" text is
load-bearing — the broad 'ND'→Table-18 reroute was empirically net-negative
for pitched lofts).
API SAP eval: 52.1% -> 53.1% within 0.5; <1.0 67.2% -> 68.0%; median |err|
0.475 -> 0.467; mean|err| 1.497 -> 1.424; flat-roof bucket within-0.5
23% -> 35% (11 improved, 2 regressed).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
An as-built cavity wall (wall_insulation_type=4) lodged "Cavity wall, as
built, insulated (assumed)" was routed to RdSAP 10 Table 6's "Filled
cavity" row. Per Table 6 (England, PDF p.41) the Filled-cavity row carries
the "†" footnote ("assumed as built") only at age bands I-M, where it is
numerically identical to "Cavity as built"; at bands A-H the Filled-cavity
row represents a GENUINE fill, not the as-built assumption. So an as-built
cavity must use the "Cavity as built" row at all bands (band G/H = 0.60,
not the filled 0.35).
This is the same latent A-H bug slice S0380.210 fixed for the "partial
insulation (assumed)" variant but left in place for "insulated (assumed)"
by a legacy production convention. The API SAP-accuracy cohort over-rated
"Cavity wall, as built, insulated (assumed)" certs at bands G/H by a clean
+1.38 / +1.61 SAP median (n=37 / n=18); bands I-M were unaffected (rows
coincide), confirming the spec mechanism per-band.
Retires the `_cavity_described_as_filled` description sniffer — as-built
cavities now always use the as-built row regardless of the rendered
insulation adjective; a genuine retrofit fill is still caught by the
explicit wall_insulation_type=2 branch.
API SAP eval: 48.6% -> 52.1% within 0.5; <1.0 63.8% -> 67.2%; median |err|
0.548 -> 0.475; mean|err| 1.561 -> 1.497; 909 computed, 0 raises.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Electric immersion water heating (WHC 903) on an off-peak tariff billed
100% at the low rate, under-costing the dwelling and over-rating it
(median +0.98 SAP across the off-peak WHC-903 API cohort, n=57).
SAP 10.2 Table 12a "Immersion water heater" row (PDF p.191) routes the
water-heating column to Table 13 (PDF p.197): the high-rate fraction is
a function of cylinder volume V, assumed occupancy N (Appendix J Table
1b) and single-/dual-immersion. The remainder bills at the low rate.
Table 13 Note 2 supplies exact equations equivalent to the rounded grid;
`electric_dhw_high_rate_fraction` evaluates them (validated against the
published 110 L grid cells). Per Note 1 the 10-hour equations cover any
tariff with >=10 hours/day low-rate (so 18-/24-hour use that column).
Immersion code mapping CONFIRMED 1=dual, 2=single via RdSAP 10 §10.5
(PDF p.54 — an immersion is "assumed dual" on a dual/off-peak meter)
cross-checked against the API cohort (code 1 sits 3.6:1 on dual meters;
code 2 on single meters). This INVERTS an earlier handover's unverified
"1=single, 2=dual" note — the dual code carries Table 13's small
fraction, matching the cohort over-rating direction; the single mapping
overshot in a prototype.
API SAP eval: 47.6% -> 48.6% within 0.5; <1.0 62.6% -> 63.8%;
mean|err| 1.586 -> 1.561; 909 computed, 0 raises.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
`_secondary_fraction` keyed "has a secondary" off the integer
`secondary_heating_type` code. The gov-API path surfaces the secondary as a
DESCRIPTION instead (`secondary_heating.description`, e.g. "Portable electric
heaters (assumed)") and leaves the integer code None. So a gas/oil boiler
main (not in the §A.2.2 forced-secondary set) with an assumed portable-electric
secondary dropped the secondary entirely (sec_kWh=0), under-costing the
dwelling and over-rating its SAP.
Per RdSAP §A.2.2 / SAP 10.2 Table 11, a lodged secondary is costed at its
Table 11 fraction (cat-2 boiler = 0.10, billed at standard-rate electricity per
the §A.2.2 assumed portable-electric default). New
`_has_lodged_secondary_description` treats a real `secondary_heating.description`
as a lodged secondary; passed to `_secondary_fraction` at both call sites. The
description is authoritative — same lesson as floor_heat_loss / roof codes.
(Electric-storage mains were unaffected: they force the secondary already.)
Also adds the Table 11 fraction for main_heating_category=8 (electric underfloor,
"Integrated storage/direct-acting electric systems" = 0.10) — the strict-raise
surfaced this latent gap once cat-8 mains were routed through the lookup.
Eval: 909 computed, 0 raises, 46.9% -> 47.6% within 0.5 (+13 certs: 420 -> 433),
mean|err| 1.633 -> 1.586. 13 improved / 1 regressed (2610, a cat-10 room-heater
cert with an independent over-count). Bucket "Portable electric heaters"
median +2.73 -> ~0 on the gas/cat-2 subset (cat-7 storage was already correct).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
`_BOILER_NO_ROOM_THERMOSTAT_CONTROL_CODES` held only {2101, 2102} — it was
keyed off the Table 4e "+0.6 °C" annotation rather than the actual interlock
criterion. SAP 10.2 §9.4.11 (PDF p.66): "A boiler system with no room
thermostat (or a device equivalent in this context, such as a flow switch or
boiler energy manager) ... must be considered as having no interlock", and
"TRVs alone ... do not perform the boiler interlock function". A fixed bypass
likewise provides no interlock (it keeps water circulating when TRVs close).
So control 2107 ("Programmer, TRVs and bypass") and 2111 ("TRVs and bypass")
lack interlock and must take the Table 4c(2) −5pp Space+DHW seasonal-efficiency
adjustment and the Table 4f footnote a) ×1.3 circulation-pump uplift — both of
which they previously missed. (2108 flow switch / 2109 boiler energy manager
carry interlock-equivalent devices → excluded; 2103-2106/2113 have a room
thermostat.) All affected certs are cat-2 gas boilers, where §9.4.11 applies.
Eval: 909 computed, 45.3% → 46.9% within 0.5 (+14 certs: 412 → 426), mean|err|
1.659 → 1.633. Bucket means corrected: control 2107 +1.50 → +0.32 (n=38),
2111 +1.48 → +0.16 (n=4). 32 improved / 10 regressed (all small; the six that
crossed out of ±0.5 were coincidentally-accurate offsetting-error certs).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Pulls in 42 commits of calculator/mapper accuracy fixes from the per-cert
mapper-validation and floor/roof/heating fronts.
Conflict resolutions:
- mapper `_is_elmhurst_roof_window`: main dropped the branch's "wall location →
vertical" guard (it broke cert 000516's rooflight), but that re-broke cert
001431's two External-wall U>3.0 windows (which must stay vertical). The two
certs lodge a BYTE-IDENTICAL §11 row, so neither location nor U separates
them — the real discriminator is the room-in-roof context. Replaced the
unconditional U>3.0 backstop with one gated on the BP having a room-in-roof
(`_elmhurst_bp_has_room_in_roof`): 000516's Main BP has a "Room in roof type
1" (→ rooflight), 001431's does not (→ vertical). Validated against BOTH —
full Elmhurst worksheet suite 1038 pass + the 001431 window-extraction pin.
- property_postgres_repository: kept main's `ids_by_uprn` method + the branch's
`_restrictions_of` helper.
- sap_fuel.py: the branch relocated it to domain/billing/ (already carrying
main's to_table_32_code normalization), so kept the old path deleted.
Fallout from main's fabric fixes (validated by the boiler-3 real-cert pin which
still reproduces at delta 0):
- re-pinned the boiler-1 + boiler-instant-hw ASHP snapshot scores;
- main's §14.2 gas-boiler main-fuel derivation resolved the BGB/102 baseline
gap, so `test_gas_boiler_instant_hw_before_baselines` is now a passing test
(was an xfail tripwire).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 6 of the Solar PV Recommendation Generator (ADR-0026). `recommend_solar`
emits one "Solar PV" Recommendation of up to five conservatively-sized configs
× {no battery, battery} = ≤10 competing Options (a free Optimiser candidate).
Each Option folds a SolarOverlay built from the chosen config: one
PhotovoltaicArray per non-north segment (peak_power = panels × panelCapacityW /
1000; orientation/pitch from geometry; generation-calibrated overshading),
is_dwelling_export_capable set True absolutely, a diverter when the dwelling
has a cylinder (None for a combi), a 5 kWh battery for the battery variant, and
the per-config composite cost from Products.solar_bundle_cost.
Eligibility = house/bungalow ∧ not listed/heritage (blocks_internal, the same
gate as ASHP — a conservation area does NOT block PV) ∧ no existing PV ∧ a
feasible SolarPotential. Flats and existing-PV top-up are deferred.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 7 of the Solar PV Recommendation Generator (ADR-0026). Adds the
composite per-dwelling Solar PV cost on the Products collection (ADR-0025
pattern): pv_system(kWp band, nearest of the ECOPV06-13 EA bands 1.0→4.5 kWp,
floor/cap at the ends) + scaffolding(£900 first elevation + £450 each
additional, default 2) + enabling base (EICR £150 + DNO £50 + 2-way consumer
unit £330) + [diverter £980 if cylinder] + [battery if the with-battery
variant] → Cost(total, contingency_rate 0.15).
Rates are data in the committed solar_rates.json (Southern Housing "SOLAR PV &
BATTERY" EA column), loaded via SolarRates.from_json/.default and injectable.
The £2,000 / 5 kWh battery is NOT on the rate sheet — a flagged estimate
(battery_estimate=true), confirmed with the user to stand in until a DB rate.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 5 of the Solar PV Recommendation Generator (ADR-0026). Adds the flat
`SolarOverlay` and `_fold_solar`, the sixth Simulation Overlay surface: like
the ventilation/lighting overlays it targets no building part and folds its
fields onto `sap_energy_source` (home of the SAP Appendix M PV inputs) —
photovoltaic_arrays (absolute target, one PhotovoltaicArray per non-north
segment, replacing the dwelling's existing arrays), pv_diverter_present,
pv_connection, is_dwelling_export_capable (set True absolutely), pv_batteries.
Omitted fields leave the baseline unchanged (combi → no diverter); the
baseline is never mutated.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 4 of the Solar PV Recommendation Generator (ADR-0026).
`select_conservative_configs` turns Google's full solarPanelConfigs ladder
into up to five competing array configs for the Optimiser: drop north-facing
planes (within 30° of due north, wrap-aware), cap usable panels at ~70% of
maxArrayPanelsCount (imagery misses obstructions; MCS edge setback), collapse
rungs that trim to the same usable size keeping the higher-generation layout,
then sample five spanning min→max by expected generation. Returns () when
nothing usable remains.
Real London example → 5 rungs at 4/12/19/26/34 panels (all ≤34.3 = 70% of
49); synthetic cases pin the north-drop and the 70% cap.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 3 of the Solar PV Recommendation Generator (ADR-0026). Per roof segment,
back-solve the effective overshading factor ZPV from Google's expected
generation against SAP's own unshaded annual output:
ZPV = (yearlyEnergyDcKwh × 0.955) / (0.8 × kWp × S)
reusing the calculator's Appendix U3.3 annual solar radiation S via a new
public seam `pv_annual_solar_radiation_kwh_per_m2`. Dividing Google's
generation by SAP's S cancels orientation/tilt and isolates shading; the
result snaps to the RdSAP bucket {1:1.0, 2:0.8, 3:0.5, 4:0.35} via the
ADR-0026 midpoint cutpoints (≥0.90→1, 0.65–0.90→2, 0.425–0.65→3, <0.425→4;
ZPV>1→1). The real London example's planes all back-solve to ZPV>1 → code 1.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 2 of the Solar PV Recommendation Generator (ADR-0026). Adds the
strictly-typed `SolarPotential` domain projection over the raw Google Solar
`buildingInsights` JSON that Ingestion persists (SolarRepository): the
`solarPanelConfigs` ladder, each rung broken into its roof segments with
Google's continuous azimuth/tilt mapped to the SAP octant
(`azimuth_to_sap_octant`, 0°=N clockwise → 1=N..8=NW, matching the
calculator's ORIENTATION_BY_SAP10_CODE) and RdSAP §11.1 pitch code
(`pitch_to_sap_code`, snap to {0→1,30→2,45→3,60→4,90→5}).
Pinned against the real London buildingInsights example (mirrored into
fixtures from the user-provided RTF): 400 W panels, maxArrayPanelsCount 49,
46-rung ladder, per-segment SE/NW/NE/SW octants at ~32° → pitch code 2.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The API `floor_heat_loss` code is authoritative — confirmed by joining each
single-BP cert's code to its independent `floors[].description` (which the
gov register publishes alongside the code):
code 1 ↔ "To external air" (exposed, 9/9)
code 2 ↔ "To unheated space" (semi-exposed, 6/6)
code 3 ↔ "(other premises below)" (partially htd, 9/9)
code 6 ↔ "(another dwelling below)" (party, 176/176)
code 7 ↔ "Solid"/"Suspended …" (ground, all)
Code 3 was mis-mapped to "To unheated space" (semi-exposed) and, on
mid-/top-floor flats, had its floor area zeroed entirely by the
dwelling-level exposure heuristic. RdSAP 10 §3.12 (PDF p.25) classes a
flat's floor over non-domestic "other premises … heated, but at different
times" as "above a partially heated space" → the §5.14 (PDF p.47) constant
U=0.7 W/m²K — distinct from semi-exposed (Table 20) and party (no loss).
Fix: the mapper sets `is_above_partially_heated_space` on the floor=0
dimension for code 3 (string → "(other premises below)" for fidelity), and
the heat-transmission step lets that per-BP lodgement override the flat
suppression upward (mirroring the existing exposed / "another dwelling
below" overrides). The cascade already routes is_above_partial → U=0.7.
Re-pins golden cert 7536-3827: its Ext2 (bp3) lodges code 3, but the cert's
lossy `floors[]` summary dropped that description, so a prior agent guessed
"code 3 = ground" (U=1.12) and concluded the residual was an irreducible
"register-rounding" artifact. It was this bug: Ext2 floor U 1.12 → 0.70,
PE -6.1952 → -5.6414, CO2 -0.1639 → -0.1492 (both toward 0), SAP unchanged.
Eval: 909 computed, 45.1% → 45.3% within 0.5, mean|err| 1.702 → 1.659,
<1.0 59.5% → 60.2%. 13 code-3 certs improve (0380 +3.71 → -0.63, 0350
+7.82 → +0.83, 2610 +7.47 → -1.29); the few that overshoot were already
failing and carry independent fabric bugs (9763's walls = 8 W/K for 60 m²).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A mid-/top-floor flat whose lowest floor is lodged as an exposed floor
(API floor_heat_loss=1) had its floor area zeroed by the dwelling-level
exposure heuristic, which keys only on the flat label and defaults
has_exposed_floor=False (assuming the floor sits over another *heated*
dwelling). RdSAP 10 §3.12 (PDF p.25) is explicit:
"Otherwise the floor area of the flat ... is:
- an exposed floor if there is an open space below"
i.e. a flat cantilevered over a passageway IS a heat-loss floor on
Table 20. The per-BP `is_exposed_floor` lodgement is authoritative and
now overrides the dwelling-level suppression upward, mirroring the
existing "another dwelling below" party override (which suppresses
downward). The code-1↔"E To external air" enum is confirmed by the
paired API+Summary worksheet certs (0350, 3800).
Eval: 45.1% → 45.3% within 0.5 (909 computed); cert 3836 +6.79 → +0.77,
5717 +1.31 → -0.07 and 0997 +0.76 → +0.05 cross into <0.5. Two
already-failing under-rated certs (7636, 2241) shift further — both are
dominated by independent cost-side over-counts the exposed floor merely
unmasks (7636 walls = 8.98 W/K for 33.87 m² is the real defect).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
main_heating_category=9 (warm-air systems, NOT heat pump) had no entry
in _SECONDARY_HEATING_FRACTION_BY_CATEGORY, so a warm-air main with a
lodged secondary raised UnmappedSapCode in
_secondary_heating_fraction_for_category — the last calc_raise in the
API sample (cert 0380-2197-2590-2996-2715: warm air mains gas code 506 +
electric room-heater secondary).
SAP 10.2 Table 11 (p.188): a gas/oil warm-air unit falls under "All gas,
liquid and solid fuel systems" (0.10), and electric warm air under
"Other electric systems" (also 0.10) — so 0.10 regardless of fuel. The
warm-air efficiency (Table 4a code→eff: 506→0.70) and Table 4f fan
energy were already wired; this was the only missing dispatch entry.
0380 now computes: SAP 78.1 vs lodged 77 (+1.1; the residual is per-cert
fabric/PV, not the warm-air dispatch — a faithful 0380 worksheet isn't
available, sim case 28 diverges at SAP 57 / code 502 / condensing unit).
Eval: zero raises remain, computed 908→909; mean|err| 1.703→1.702.
Regression green (2448 pass incl. golden 6035 + cohort); pyright
net-zero (44=44).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The gov EPC API field wall_insulation_thermal_conductivity is OUTPUT
metadata in the openly-published EPC, not an input to the RdSAP10 tool
(Elmhurst) that produced it — its wall entry is Type + Insulation +
thickness only, with no conductivity field. So the RdSAP10 reduced-data
method always uses the SAP 10.2 §5.8 (p.41) default λ=0.04 W/m·K,
whatever code the register lodged.
`_resolve_wall_insulation_lambda_w_per_mk` previously mapped only code 1
(→0.04) and RAISED on others, blocking cert 2090-6909-8060-5201-6401
(code 3 on an internally-insulated 360mm solid-brick wall) with
calc_raise:ValueError. Now it returns the §5.8 default for any code.
Validated: 2090 computes to SAP 73.97 vs lodged 74 (err -0.03); λ of
0.04 / 0.03 / 0.025 all round to 74, and Elmhurst exposes no conductivity
input, so 0.04 is the spec-faithful RdSAP10 value. Eval computed
905→906; mean|err| 1.708→1.706. Regression green (only the 2 pre-existing
stone-wall U failures); pyright net-zero (69=69).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 10 of ADR-0025 costing. The Southern Housing rate table moves from code
constants into ashp_rates.json (structured rows the flat scalar catalogue can't
hold), loaded via AshpRates.from_json. Products takes an injected AshpRates
(default: the committed sheet), so rates are now data -- tunable (e.g.
reuse_distribution_fraction) without a code change, and ready for ETL/DB-supplied
rates later. Behaviour-preserving: the 6 pinned cost tests still hold against the
default, plus a new test proving injected rates drive the total.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
SAP 10.2 Table 3 (PDF p.160) names "Direct-acting electric boiler"
verbatim in the primary-loss zero list (alongside electric immersion,
combi, CPSU, integral-vessel heat pump). RdSAP 10 §12 (p.62) classifies
SAP code 191 as the direct-acting electric boiler. Its cylinder is
immersion-heated with no primary pipework, so no primary circuit loss
applies — but `_primary_loss_applies` had no 191 branch, so a 191 main
(main_heating_category 2, "Boiler and radiators, electric") fell through
to the cat-{1,2} boiler branch and accrued ~1177 kWh/yr of phantom
primary loss on the electric-flat segment.
Validated against the cert-2474 worksheet: §4 (59) primary loss = 0,
(64) HW output 1760 (cylinder) + (64a) shower 581. Cert 2474 HW kWh
3585 → 2408; SAP 64.66 → 70.35 (the residual to the lodged 78 is an
Unknown-meter data-fidelity artifact — the register recorded meter_type=3
"Unknown" but the lodged rating used an 18-hour off-peak meter, per RdSAP
§12 / the example worksheets).
Eval mean|err| 1.720 → 1.708 (headline 45.0%, flat ±1 cert — the
electric-flat segment is dominated by the meter data-fidelity artifact).
Regression green (2448 pass incl. golden 6035 + ASHP cohort 1e-4);
pyright net-zero.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 9 of ADR-0025 costing. _ashp_option now prices via Products.ashp_bundle_
cost(ashp_cost_inputs(epc)) instead of the flat catalogue scalar; the catalogue
row is still read for its material_id. Pinned on boiler-3: gas reuse dwelling
composes to 15600.60 (decommission 720 + pump 9720 + cylinder 2382.60 + reuse
distribution 2778) with 25% contingency.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 8 of ADR-0025 costing. _existing_system keys on the heating fuel code,
not the mains_gas flag -- the 001431 electric fixtures all lodge mains_gas=True
(gas available at the property) while heating electrically (fuel 30), which the
flag-based check misread as gas (and would have wrongly reused a non-existent
wet system). Electric/gas/oil/LPG map to their categories; empty details ->
NONE; unrecognised -> OTHER (gas-line fallback).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 7 of ADR-0025 costing: the modelling-layer interpretation half of the
split. ashp_cost_inputs derives existing system (mains_gas/fuel/SAP-code),
size band (floor area <= 75 m2), design heat loss (floor_area x 0.05 -- the
chosen proxy over HLC, ADR updated), radiator count (habitable + 3, floor-area
fallback) and reusable-wet-system flag. Catalogue math (Products) stays
EPC-free. ADR-0025 updated to record the floor-area pump-sizing choice.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 4 of ADR-0025 costing. ASHP is offered to any house regardless of fuel,
so _decommission now prices a fallback instead of raising: no system -> 0,
electric room/panel heaters -> electric-storage line, anything else -> gas
line (representative default). Never blocks ASHP eligibility.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 3 of ADR-0025 costing. When the dwelling has a reusable wet system,
_distribution charges a power-flush (168) plus _REUSE_DISTRIBUTION_FRACTION
(0.5) of the full radiator band -- a documented stand-in for partial radiator
upsizing at ASHP flow temps, the headline uncertainty in the model. Without a
wet system the full new distribution is priced.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 2 of ADR-0025 costing. _decommission maps the existing system to its
Southern Housing line: gas/oil flat 720, LPG 960 (tank+fuel removal),
electric-storage 570/840 by property-size band. Unmapped systems raise for
now -- the no-system/electric-other/other fallbacks land in the next slice.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
First slice of the per-dwelling ASHP bundle costing (ADR-0025). Products is
the rich catalogue collection over Product, owning the catalogue math: given
a typed AshpCostInputs it sums the applicable Southern Housing rate lines
(decommission + heat-pump band + fixed cylinder + full wet distribution) into
a Cost with the separate 25% ASHP contingency. Pure -- no EpcPropertyData or
calculator. Pinned exact (1e-9) against the real rate sheet. Reuse branch,
decommission variants, fallbacks, band edges and radiator clamp follow.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
When DHW is heated by the main heat pump (WHC 901/902/914 = "from main
system") and the main carries a PCDB Table 362 record,
`_hot_water_fuel_cost_gbp_per_kwh` billed the electric HW at 100% off-peak
low rate (its long-standing TODO). SAP 10.2 Table 12a Grid 1 WH column
(PDF p.191) puts HP-DHW on the ASHP/GSHP-from-database row: 0.70
high-rate fraction at 7-hour and 10-hour → 0.70×14.68 + 0.30×7.50 =
12.526 p/kWh (10-hour), not 7.50 p. The low-rate collapse over-credited
the cat-4 HP-DHW cluster.
Fix: pass the cert WHC into the helper and, for HP-DHW (WHC ∈ {901,902,
914} + PCDB-HP main), bill at the ASHP_APP_N WH blended rate. Electric
IMMERSION (WHC 903) is a different Table 12a row (off-peak immersion 0.17
/ Table 13) and stays on the 100%-low-rate fallback until that slice
lands.
cat-4 cluster (20 certs): mean|err| 2.43→2.11, mean signed +0.06→-0.52
(now per-cert scatter, no systematic bias); cert 9472 +6.4→+3.2, 2789
+6.8→+4.0, 4135 +2.7→within 0.5. Headline mean|err| 1.727→1.720.
Regression green (2447 pass incl. golden 6035 + ASHP cohort at 1e-4);
pyright net-zero.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A heat pump that resolves via its PCDB Table 362 index alone (API path,
data_source=1, no Table-4a SAP code) had sap_main_heating_code=None, so
`_table_12a_system_for_main` fell through the 211-227/521-524 code-range
gate to None → the "100% off-peak low-rate" fallback. On a Dual meter
(RdSAP §12 Rule 3 routes heat pumps to the 10-hour tariff) this billed
space heating at 7.50 p/kWh instead of the SAP 10.2 Table 12a Grid 1
(PDF p.191) ASHP/GSHP-from-database row: 0.80 high-rate fraction →
0.80×14.68 + 0.20×7.50 = 13.244 p/kWh. The collapse over-credited the
whole cat-4 heat-pump cluster.
Fix: route any main with a PCDB heat-pump record to ASHP_APP_N regardless
of SAP code (a Table 362 record IS an Appendix-N heat pump by
definition). ASHP_APP_N and GSHP_APP_N share the 0.80 SH fraction at
7h/10h, so ASHP_APP_N is the canonical Appendix-N row for the SH split.
cat-4 cluster (20 certs): within-0.5 45%→50%, mean signed +1.43→+0.06,
mean|err| 3.81→2.43; cert 9472 +15.0→+6.4, 2789 +13.4→+6.8. Headline
45.0%→45.1%, mean|err| 1.757→1.727. Regression green (only the
pre-existing test_total_floor_area fails); pyright net-zero.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Electric storage heaters (and CPSU) charge overnight and cannot run
economically on a single rate, so their presence is physical evidence the
dwelling is on an off-peak tariff. RdSAP 10 §12 (PDF p.62) applied Rules
1-4 only for a Dual meter; an "Unknown" (code 3) meter returned STANDARD
without consulting the heating type, so a cat-7 storage main billed its
overnight charge at the standard 13.19 p/kWh instead of the 7-hour low
rate (5.50 p/kWh) — ~2.4x too high → large under-rate.
Two coupled fixes:
- `rdsap_tariff_for_cert`: for an Unknown meter, infer the off-peak tariff
from a Rule-1 CPSU (→10-hour) or Rule-2 storage (→7-hour) main; keep
STANDARD otherwise. Direct-acting/room heaters/heat pumps (Rule 3) are
NOT off-peak evidence (run on demand, exist on single-rate meters) so
they stay STANDARD — billing them 100% at the low rate over-credits.
- `_fuel_cost` now resolves its tariff via the §12-aware `_rdsap_tariff`
(not the raw `tariff_from_meter_type`), so the off-peak branch fires for
these storage certs and the legacy scalar fields bill the low rate.
Mirrors `_is_off_peak_meter`'s existing Unknown+electric heuristic (which
already routes HW/secondary off-peak), closing the main-space-heating gap.
Meter-3 electric cluster: mean |err| 11.18 → 6.52, within-1.0 3 → 5 (cert
7336 -26.1 → -0.16, 0380 -19.9 → +1.0). Eval headline 44.9% → 45.0%, mean
|err| 1.82 → 1.76, mean signed -0.08 → +0.02. A few storage certs overshoot
(other residuals the standard rate was masking).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The main pitched/flat roof U-value was derived from the JOINED text of
every roofs[] entry. A room-in-roof carries its own §3.9/§3.10 shell
area + U-value cascade (Table 17 / Table 18 col 4), so a multi-roof cert
lodged "Pitched, insulated (assumed) | Roof room(s), no insulation
(assumed)" leaked the RR's "no insulation" marker into the main roof's
u_roof → U=2.30 applied to the WHOLE main roof, ~3x over-stating its heat
loss. This is the 4700-family regular-roof-U leak.
`_joined_main_roof_descriptions` drops "Roof room(s)" entries before the
main-roof u_roof, falling back to the unfiltered join only for pure-RR
dwellings (every entry an RR) to preserve their prior behaviour. The RR
shell U is unaffected (computed separately) — golden 6035 stays green.
RR-leak cluster (18 certs, RR "no insulation" + a non-RR primary roof):
mean |err| 6.14 → 4.85, within-1.0 0 → 8, within-0.5 0 → 3. Eval headline
44.8% → 44.9%, mean |err| 1.851 → 1.824, mean signed -0.152 → -0.081. Two
certs overshoot (other residuals the leak was masking); the spec rule is
applied uniformly.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A roof lodged "Unknown loft insulation" carries roof_insulation_thickness
"NI" (Not Indicated → parsed to 0) or "ND" (None): the thickness is
UNDETERMINED, not zero. RdSAP 10 §5.11.4 (p.44) is deterministic here —
"U-values in Table 18 are used when thickness of insulation cannot be
determined" — so the roof takes the Table 18 age-band default (column (1)
pitched / column (3) flat), NOT the uninsulated 2.30 the Table 16 row-0
lookup returns for a parsed-0 thickness. The "Unknown" text is RdSAP's
rendering of the undetermined-thickness observation, distinct from a
genuine "no insulation" lodgement (which keeps 2.30).
u_roof gains an "unknown"-description branch ahead of the parsed-0 → 2.30
path, gated on undetermined thickness (None or 0). Top-floor flats with
"Pitched/Flat, Unknown ... insulation" were the worst electric-flat
under-raters: roof U=2.30 gave HLP ~3.7 on dwellings rated SAP 69-70.
Cluster (14 certs, roof desc contains "unknown", no "no insulation"):
mean |err| 7.79 → 1.82, within-0.5 1→4, within-1.0 1→6. Cert 9836
roof_w_per_k 58.2→10.1, SAP -27.8 → -3.5. Eval headline 44.4% → 44.8%,
mean |err| 1.944 → 1.851. Two certs overshoot (other residuals the wrong
roof-U was masking); the spec value is applied uniformly regardless.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A floor lodged API floor_heat_loss=6 ("another dwelling below") sits over
another heated dwelling, so it is a party floor with no heat loss (RdSAP
10 §3). The mapper mapped code 6 → None and the heat-transmission step
drove floor exposure solely from the dwelling-level `has_exposed_floor`
flag — which is keyed only on the dwelling_type label and defaults a
"Ground-floor flat" to an exposed floor. So a ground-floor flat above a
basement dwelling kept its full ground-floor heat-loss area.
Map code 6 → "(another dwelling below)" (still != "Ground floor", so the
§5 (12) suspended-timber rule stays inert) and have the cascade suppress
that BP's floor when its floor_type carries the signal, mirroring the
roof's existing "another dwelling above" per-BP party override.
Cert 2115-4121-4711-9361-3686 (ground-floor flat, floor_heat_loss=6):
floor_w_per_k 47.85 → 0; SAP -23.44 → -4.41. Cert 0350-…-6435 -12.38 →
-0.55; 0926-…-9024 -2.35 → -0.82. Eval mean |err| 1.982 → 1.944.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The ASHP bundle is a fixed whole-system end-state (confirmed: always the same
contractor cylinder), so the hot-water arrangement is fixed too. The overlay now
sets water_heating_code=901 ("from main system") absolutely, so a combi (909/611)
or electric (903/908) before is reset to HW-from-the-heat-pump — previously the
overlay relied on the before already lodging 901 (true for boiler-1, not in
general). No-op for the boiler-1 pin (stays 1e-4). Cascade pins for combi /
electric-with-cylinder befores await example certs. ADR-0024.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
recommend_heating now receives planning_restrictions in the orchestrator (the
ASHP planning gate); the ASHP bundle joins the free candidate pool for every
house/bungalow. Catalogue + contingency (legacy 0.25) gain air_source_heat_pump;
report.py _triggers_for explains the ASHP trigger; the harness forcing test
covers it. Integration tests seed an air_source_heat_pump MaterialRow (ASHP
fires on every house, the broadest trigger yet). NB the optimiser correctly does
NOT select ASHP for an EPC-band goal — gas->electric does not improve the SAP
cost-rating; ASHP is a CO2/PE measure, selectable once non-EPC goals land. ASHP
bundle COMPLETE (S5-S7). ADR-0024.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A typical mains-gas combi house re-lodged as an air-source heat pump closes at
1e-4 (gas-boiler 1 example from the technical specialist). Closes one named gap
the pin surfaced: a whole-system replacement to a PCDB-indexed system left the
old Table 4a sap_main_heating_code (104) beside the new heat-pump index, and the
stale code won the calculator's efficiency dispatch (hot water billed at boiler
not HP efficiency, ΔSAP 3.98). _fold_heating now enforces the mutual exclusion
of the two efficiency anchors (setting an index clears the SAP code and vice
versa). Also fixed a pre-existing pyright annotation in the lighting applicator
test. ADR-0024.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Adds the air-source heat-pump Option to the competing "Heating & Hot Water"
bundles. Its overlay is the absolute heat-pump end-state (fixed representative
PCDB index 101413 + category 4 + control 2210 + HWP cylinder + single meter +
off mains gas), pinned against the relodged after-cert next slice. Eligibility
is physical/planning only (ADR-0024, research-grounded): any non-flat
house/bungalow, not listed/heritage (PlanningRestrictions.blocks_internal —
conservation is offered with a caveat, not excluded), not already a heat pump;
floor area / built form / fuel / fabric are deliberately not gates. recommend_
heating gains a restrictions param (defaulted). An already-HHR electric house
now correctly gets ASHP as a better end-state.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A 440 mm (>420 mm) solid brick AS-BUILT wall computed U = 1.70 (the
220 mm bucket default) instead of the RdSAP-correct 1.10. The §5.7
Table 13 thickness path only fired for *insulated* brick (external/
internal + thickness > 0); the as-built case fell through to the
Table 6 cavity/solid age-band default.
Spec: RdSAP 10 Specification (9th June 2025), §5.7 "U-values for
uninsulated brick walls, age bands A to E", Table 13 (PDF p.40):
≤200 mm → 2.5, 200–280 mm → 1.7, 280–420 mm → 1.4, >420 mm → 1.1.
Table 6 footnote (b) on the "Solid brick as built" row (PDF p.40):
"Or from 5.7 if wall thickness is other than 200mm to 280mm" — the
thickness table supersedes the flat 1.7 default whenever a documentary
wall thickness is lodged (200–280 mm gives 1.7 either way). The §5.8 /
Table 14 dry-lining R is added on top only when the wall is dry-lined,
per the §5.7 closing sentence.
Validated against the user-generated Elmhurst worksheet "simulated
case 21" (replica of API cert 2818-3053-3203-2655-9204: mid-terrace,
age band B, solid brick as-built 440 mm, room-in-roof). New §3 cascade
pin `test_section_3_wall_u_by_thickness_case21_match_pdf` routes the
Summary through the real extractor + mapper and pins:
(31) 155.1000, (33) 175.6208, (36) 23.2650, (37) 198.8858 — all 1e-4.
External walls Main U → 1.1000; Sheltered RR gable → 1/(1/1.10+0.5) =
0.71 (was 0.92). Pinned on §3 only (case-6 precedent): its code-908
instantaneous multi-point gas water heater has a separate §4 (219) gap.
Cross-check: sim case 20 (220 mm) stays at 1.70 — unchanged.
API SAP accuracy (scripts/eval_api_sap_accuracy.py, 896 computed certs):
% |err| < 0.5 SAP vs lodged: 42.6% → 43.8%; mean |err| 2.045 → 2.010.
Regression: tests/domain/sap10_calculator/ (1861), backend/
documents_parser/tests/ (574), datatypes/epc/ + rdsap golden fixtures
all green (pre-existing test_total_floor_area excepted). pyright strict
net-zero. No solid-brick fixture pin shifted (200–280 mm unchanged).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The 2026 API sample raised UnmappedApiCode on `gable_wall_type` 2 (10 certs)
and 3 (4 certs) — the two RR gable variants beyond Party(0)/Exposed(1).
Sim case 21 (an Elmhurst replica of API cert 2818-3053-3203-2655-9204:
gable_wall_type_1=2, gable_wall_type_2=3) lodges them as "Sheltered" and
"Connected", confirming **2=Sheltered, 3=Connected**.
- Mapper: `_API_TYPE_1_GABLE_TYPE_TO_KIND` gains 2 → `gable_wall_sheltered`,
3 → `connected_wall` (U=0, area deducts — already handled).
- Calculator: new `gable_wall_sheltered` branch. The API path lodges no
per-gable U, so the cascade DERIVES it as RdSAP 10 Table 4 (p.22)
Sheltered = 1/(1/U_wall + 0.5) — back-solved + validated against case 21
(U_wall 1.10 → 0.71) and case 20 (1.70 → 0.92). A lodged U (Summary path)
still rides through as an override.
API sample: 14 raises clear → `computed` 882 → 896, `raise:ValueError` 16 → 2.
Summary path unchanged (Sheltered stays `gable_wall_external` + lodged U, so
cert 000487's hand-built fixture is untouched). 2861 pass (lone
test_total_floor_area pre-existing); pyright strict net-zero (32=32 / 12=12).
NOTE: the derived Sheltered U on cert 2818 lands at 0.92 not 0.71 because the
cascade computes its 440 mm solid-brick wall U as 1.70 (the 220 mm default) —
a SEPARATE wall-U-vs-thickness bug (next slice, validated by case 21's 1.10).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Locks sim case 20 (storage heaters + Detailed RR + loose-jacket cylinder)
as a golden vector: _elmhurst_worksheet_001431_case20.build_epc() routes the
Summary PDF through extractor → mapper → calculator, registered in
test_e2e_elmhurst_sap_score with all 11 SapResult headline pins at 1e-4.
10 pinned exact off slices 1-2 (window extractor, RR stud walls); this slice
closes the last one, co2_kg_per_yr (was 3797.62 vs (272) 3815.4060).
Root cause: on a dual-rate (E7) meter the CO2 path ignored the tariff's
high/low Table-12 electricity codes that the cost path already uses:
- Secondary (direct-acting portable heaters, on-peak) keyed the monthly
Table 12d cascade on standard code 30 (0.15405) instead of the E7 HIGH
code 32 → (263) 0.1616. SAP 10.2 Table 12a Grid 1 direct-acting electric
is 100% high-rate; mirrors the cost side billing it at 15.29 p/kWh.
- Main storage heaters fell through `_table_12a_system_for_main`=None to
the FLAT annual factor (0.136) rather than the dual-rate LOW code: per
the Table 12a design intent ("storage … 100% low rate") they charge
off-peak → E7 LOW code 31 → (261) 0.1357.
case-20 co2 now EXACT. 2433 calculator + 112 golden + documents_parser tests
pass — no dual-meter/storage cohort regression; pyright strict net-zero (32=32).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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>
The same absolute-target HHR overlay reproduces the common relodged after from
two different base systems (existing electric storage; "no system present"
electric) — proving the bundle is a true whole-system end-state. Closes one
named gap the pin surfaced: the relodged HHR cylinder lodges
cylinder_thermostat='Y', so HeatingOverlay + _fold_heating + the HHRSH overlay
gain cylinder_thermostat (ΔSAP 0.065 -> <1e-4). ADR-0024.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The heating Recommendation Generator (HHRSH first). Emits one "Heating & Hot
Water" Recommendation whose competing whole-system bundles the Optimiser picks
from; this slice builds the high-heat-retention storage Option. Its overlay is
the absolute HHR end-state (Table 4a code 409 + control 2404 + dual off-peak
meter + off-peak electric cylinder), pinned against the relodged after-cert in
the next slice. Eligibility translates legacy is_high_heat_retention_valid to
structured predicates (electric or off-gas main, not already HHR/heat-pump).
mains_gas and the heat emitter are unchanged by the measure, so unset. ADR-0024.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
RdSAP 10 §2 (Ventilation, "Walls" row): "Structural infiltration: 0.25
for steel or timber frame or 0.35 for masonry construction ... System
build: treated as masonry." `_is_timber_or_steel_frame` wrongly included
wall_construction code 6 (system build) alongside code 5 (timber frame),
handing system-build dwellings the 0.25 structural ACH instead of 0.35.
On the cat-10 room-heater fixture (ref 001431, walls SY System Build →
code 6) this under-stated the infiltration rate (18) by exactly 0.10
(0.45 vs worksheet 0.55), dropping the effective air change (25), the
ventilation heat loss (38)m = 0.33 × (25)m × (5), and the heat-transfer
coefficient (39) — so space-heating demand (98) came out 404 kWh low
((211) 11158.6 vs worksheet 11563.2). Restrict the 0.25 branch to code 5
only; code 6 (and everything else) is masonry at 0.35.
Pins the rating-block (38)m ventilation heat loss mean = 83.3613 W/K at
abs 1e-4 and asserts the classifier treats the system-build wall as
masonry. §4 suite green (2415 passed, 1 skipped); no existing fixture
relied on system-build → 0.25.
Residual after this slice: SAP +0.03 / cost -£0.95 — a small fabric (33)
gap (-0.15 W/K) plus lighting (232) +1.0 kWh remain as separate causes.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Water heating SAP code 909 (electric instantaneous) and 907 (single-point
gas) heat water at the point of use, serving one outlet with no
distribution pipework. Per SAP 10.2 §4 (p.23, l.1416): "'Single-point'
heaters, which are located at the point of use and serve only one outlet,
do not have distribution losses either." So worksheet (46)m = 0 and the
heat-required line collapses to SAP 10.2 worksheet l.7704
(62)m = 0.85 × (45)m + (46)m + (57)m + (59)m + (61)m
= 0.85 × (45)m (all loss terms zero for a no-cylinder system).
`distribution_loss_monthly_kwh` already supported the
`is_instantaneous_at_point_of_use` flag (and its docstring already named
codes 907/909), but `water_heating_from_cert` hard-coded it to False, so
the cascade applied (46)m = 0.15 × (45)m to single-point heaters. That
0.15 distribution loss exactly cancelled the 0.85 reduction, leaving
(62)m = (45)m. On the cat-10 room-heater fixture (ref 001431, code 909)
that over-stated the water fuel (219) as 2082.6250 instead of the
worksheet's 1770.2313, and inflated the (65)m heat gains (692.47 vs
worksheet 442.55) which in turn suppressed space-heating demand.
Thread the cert's existing instantaneous flag (`_INSTANTANEOUS_WATER_CODES`
= {907, 909}) through `_water_heating_worksheet_and_gains` into both the
demand-pass and final `water_heating_from_cert` calls.
Pins (219) water fuel = 1770.2313 at abs 1e-4 via the extractor → mapper →
rating cascade. §4 suite green (2414 passed, 1 skipped); no existing
fixture exercised the 907/909 path. The residual space-heating fuel gap
((211) 11158.59 vs worksheet 11563.17) this exposes is a separate cause —
next slice.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The 5th EpcSimulation overlay surface and the deepest applicator fold yet: a
heating bundle is a whole-system replacement, so _fold_heating routes its
absolute-target fields across main_heating_details[0] (fuel/emitter/control +
sap_main_heating_code OR index+category), sap_heating (water_heating_* +
cylinder), the top-level EpcPropertyData (has_hot_water_cylinder), and
sap_energy_source (meter_type, mains_gas). ADR-0024.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The fuel codes the calculator now puts on SapResult are its own codes — raw
gov-API enums or already-Table-32, depending on the source mapper (ADR-0015).
sap_code_to_fuel now runs the code through table_32.to_table_32_code
(promoted from private _to_table_32_code) — T32-first, then API-translate,
the SAME normalization the calculator's pricing/CO2 helpers use — before the
Table-32 -> Fuel dispatch, so the bill's carrier matches what the calculator
billed (incl. the API/T32 collision codes, e.g. 20 = wood-logs not heat-net).
Falls back to the raw code for billing fuels the price table omits (the 41-58
heat-network range), which resolve to HEAT_NETWORK -> UnpricedFuel — stricter
than, and intentionally divergent from, the calculator's lossy
default-to-mains-gas for an unpriced code (ADR-0014 §5).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
ADR-0014 BillDerivation attributes each end-use (HEATING / HOT_WATER /
SECONDARY / APPLIANCES / COOKING) to a fuel carrier and credits PV
export. SapResult already carried the per-end-use kWh but not WHICH
fuel each end-use burns, nor the annual exported kWh — so a downstream
SapResult->EnergyBreakdown adapter could not pick the right tariff.
Surfaces five output-only fields, threaded exactly like the recently
merged appliances/cooking change (2f039aeb):
main_heating_fuel_code RdSAP10 Table 32 / SAP 10.2 Table 12 fuel
main_2_heating_fuel_code code column (the lodged fuel code, e.g.
secondary_heating_fuel_code mains gas 26). None when the corresponding
hot_water_fuel_code system is absent / fuel not resolvable.
pv_exported_kwh_per_yr SAP 10.2 Appendix M1 §3-4 annual export kWh
(0.0 when no PV).
cert_to_inputs.py populates the four fuel codes from the existing
resolvers the cost/CO2 cascade already uses — `_main_fuel_code`,
`_secondary_fuel_code`, `_water_heating_fuel_code` (not reinvented);
Main 2 is the second `main_heating_details` entry, guarded for length.
There is a single CalculatorInputs construction site (cert_to_demand_
inputs delegates to cert_to_inputs). `pv_exported_kwh_per_yr` already
existed on CalculatorInputs; SapResult collapses its Optional to 0.0.
HARD CONSTRAINT honoured — output-only, zero rating drift. These fields
do NOT feed ECF / total_fuel_cost_gbp / co2_kg_per_yr / primary_energy_*
/ sap_score / any monthly value. Every golden-fixture, Elmhurst e2e
SapResult pin, section cascade pin, and heating-corpus residual stays
byte-identical: calculator suite 1658 -> 1661 passed (+3 new tests),
4 skipped, 0 failed before and after. pyright net-zero (51 -> 51 in
domain/; no new errors in the touched test files).
New tests: a synthetic threading test (four fuel codes + PV export pass
unchanged through calculate_sap_from_inputs; None PV collapses to 0.0)
and a cert-level pin (mains-gas combi cert 000516 -> main fuel code 26,
no Main 2, secondary 30, HW 26). Synthetic CalculatorInputs / SapResult
fixtures updated for the new SapResult fields (defaults cover Inputs).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
