Model/domain/modelling/contingencies.py
Khalim Conn-Kowlessar 46bca47365 feat(modelling): Products.solar_bundle_cost + committed solar rate sheet
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>
2026-06-08 12:10:27 +00:00

35 lines
1.2 KiB
Python

"""Per-Measure-Type contingency rates.
The one cost component carried separately from a Product's fully-loaded total
(CONTEXT.md). Mirrors the legacy `recommendations/Costs.py::Costs.CONTINGENCIES`;
extended as each measure type lands.
"""
_CONTINGENCY_RATES: dict[str, float] = {
"cavity_wall_insulation": 0.10,
"loft_insulation": 0.10,
"sloping_ceiling_insulation": 0.10,
"flat_roof_insulation": 0.10,
"suspended_floor_insulation": 0.20,
"solid_floor_insulation": 0.26,
"mechanical_ventilation": 0.26,
"external_wall_insulation": 0.26,
"internal_wall_insulation": 0.26,
"double_glazing": 0.15,
"secondary_glazing": 0.15,
"low_energy_lighting": 0.26,
"high_heat_retention_storage_heaters": 0.10,
"air_source_heat_pump": 0.25,
"solar_pv": 0.15,
}
def contingency_rate(measure_type: str) -> float:
"""Return the contingency rate for a Measure Type, raising if unknown
(strict — do not silently default, per the repo's strict-raise convention)."""
try:
return _CONTINGENCY_RATES[measure_type]
except KeyError as exc:
raise ValueError(
f"no contingency rate configured for measure type {measure_type!r}"
) from exc