Rich certs (14/1000) use lodged window_area; the windowless majority synthesise
glazing from the glazed_area band via _synthesise_17_1_sap_windows (own seam,
inherited 20.0.0 coefficients); lighting/ventilation/hot-water mirror 18.0.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The first overlay surface that sets fields to *absent* rather than to a
target state: _fold_secondary_heating clears sap_heating.secondary_heating_type
+ secondary_fuel_type, so the calculator's Table 11 secondary-fraction split
(SAP 10.2 §9a) routes 100% of space heating to the main. On an electric-storage
main RdSAP §A.2.2 re-forces a default secondary, making removal a no-op there —
left to the Optimiser to de-select (ADR-0028 decisions 2-3).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Schema-fix delivered in the prior slice; this promotes the 1000-cert corpus
into the strict guard (matches 18.0/20.0.0).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Documents the inherit-and-validate decision for 18.0: reuse 20.0.0's 0.148 +
band multipliers (the corpus can't self-fit — 958/1000 band-1 with no measured
band-1 windows), validated against 18.0's own band-4 rich certs (0.223 obs vs
0.148 x 1.51 pred). References ADR-0027 one-way (keeps the accepted ADR immutable).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Behaviour delivered by the band-multiplier dict in the prior slice; this pins
the band-2 ("More than typical") case against the inherited 20.0.0 coefficient.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Don't offer a like-for-like gas boiler swap to a dwelling whose existing gas
boiler is already at least as efficient as the new condensing boiler (SAP 10.2
Table 4b codes 102/104 = 84% winter) — it gains nothing, and the dwelling gets
the tune-up (cylinder + controls) instead. `_already_condensing` compares the
existing code's Table 4b winter efficiency to 84%; a non-Table-4b code (solid
fuel) has no comparable efficiency and is never treated as already-condensing.
The gate is GAS-ONLY: a non-gas boiler → gas is a fuel switch whose value (cost
/ carbon) is not captured by winter efficiency, so oil/LPG/coal → gas is never
suppressed on efficiency grounds (only gated on the mains-gas connection).
This correctly demotes the gas-with-cylinder example (cert lodges code 114
"Regular, condensing", 84% winter) to a tune-up case — confirming that 114→102
is ~0 boiler-efficiency gain in both our calc and Elmhurst (both Table 4b 84%);
Elmhurst's uplift there came from the cylinder + flue, not the boiler. The
boiler-with-cylinder overlay stays validated by the lpg pin (code 115, non-
condensing + cylinder) and by recasting the 114 fixtures' code to a pre-1998
non-condensing boiler (110) in the boiler tests — the overlay overwrites the
code to 102 regardless, so only eligibility changes, not the delta-0 result.
New tests: an already-condensing gas boiler yields no boiler upgrade (but a
tune-up); an oil condensing boiler is not gated (the fuel switch survives).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Replace the flat placeholder scalars (boiler £3000; tune-up £500/£900) with a
per-dwelling composite cost, mirroring the ASHP architecture (ADR-0025): a
`HeatingRates` table (data, `heating_rates.json`), typed `BoilerCostInputs` /
`TuneUpCostInputs`, pure `Products.boiler_bundle_cost` / `tune_up_cost`, and
modelling-layer interpreters that read the dwelling into those inputs.
The cost mirrors the Simulation Overlay component-for-component, sharing the
controls + cylinder pricing across both options:
- tune-up (standard) = standard controls + cylinder fixes
- tune-up (zone) = zone controls + cylinder fixes
- boiler upgrade = £3200 all-in + standard controls (only when the upgrade
fired a controls change) + cylinder fixes
Standard controls are priced INCREMENTALLY — only the parts missing to reach
SAP 2106 (programmer £120 / room thermostat £150 / TRV £35×radiators), read
from a Table 4e Group-1 feature map so a dwelling that already has a room
thermostat + TRVs is only charged the programmer. Zone controls are a full
smart kit (hub £205 + smart TRV £50×radiators) — the smart TRV is itself the
room sensor, so there is no separate per-room sensor line. Cylinder fixes:
jacket £50 (when under-insulated) + thermostat £150 (when absent). The boiler
is a like-for-like wet swap (no radiators/flue/pipework — eligibility already
requires an existing wet boiler), so those dead-code extras are not modelled.
Figures are research-validated 2025/26 UK installed costs (legacy Costs.py
lineage); fully-loaded totals with one contingency on top (Model B, not the
legacy VAT/preliminaries engine). Contingency: boiler 0.26; tune-ups 0.10
(was a 0.15 placeholder). ADR-0027 records the design; CONTEXT.md's Heating
Eligibility entry updated to cover the partial boiler/tune-up family + composed
cost. Products cost pins (delta<=1e-9) + interpreter tests + generator
composite-cost assertions.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Drops the xfail now that Reduced-Field Synthesis (ADR-0027) maps every
20.0.0 cert; the corpus test holds the whole bucket to a strict 1000/1000.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
ADR-0027 Reduced-Field Synthesis: certs with no per-window array now get total
glazing = 0.148 x TFA x band-multiplier (median + quartile multipliers fit from
the 1000 real 21.0.1 certs), split 4-way across N/E/S/W with width=area/4,
height=1.0; glazing_type routed through the verified 21.0.1 cascade. Also guard
optional PhotovoltaicSupply.none_or_no_details (a parse straggler). Corpus maps
983/1000, up from 974.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Required->optional defaults (kw_only + data-driven from corpus presence) so
993/1000 certs that omit sap_windows parse, and honest Union[str, DescriptionV1]
typing for description/dwelling_type which the corpus lodges as localised dicts
in ~half the certs. The never-run 20.0.0 mapper path now produces EpcPropertyData;
974/1000 corpus certs map (xpass), up from 7.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Sharpen the glossary to decouple deterministic old-schema re-mapping from
neighbour-prediction gap-fill (a separate, unimplemented ML path), and add
the Reduced-Field Synthesis term. ADR-0027 records the pre-SAP10 20.0.0
mapper's best-attempt synthesis (corpus-fit glazing 0.148xTFAxband, 4-way
orientation) and its trade-offs. Grill resume doc captures every resolved branch.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
