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>
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>
Slice 6 of ADR-0025 costing. Characterises the distribution clamp built in the
tracer: a radiator proxy below 4 prices as the 4-rad band, above 12 as the
12-rad band, in-range exact.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 5 of ADR-0025 costing. Characterises the pump-band selection built in
the tracer: a design heat loss is rounded UP to the smallest covering band
{5,8,11,15,16+} kW, and loads above the largest band take the top rate. Edge
pins (5.0/5.01/8.0/8.01/11.0/15.0/15.01/25.0) lock the boundaries.
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>
