Model/domain/modelling/generators/wall_u_value_gate.py
Khalim Conn-Kowlessar 7c8b161653 Solid-wall insulation is withheld when it cannot lower the derived wall U 🟩
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-07-03 11:40:41 +00:00

80 lines
3.1 KiB
Python

"""The Wall U-Value Gate (ADR-0051).
A wall insulation Option is offered only when it would actually lower the main
wall's derived U-value: on a modern construction age band RdSAP's Table 6-10
cascade assigns an as-built wall its at-regs U-value, and the post-measure
state resolves to the *same* value — the measure costs thousands for +0.00 SAP
(property 711795, PRD #1435 WS2: timber frame at age band L, 0.280 → 0.280).
The comparison uses a deliberately thin `u_wall` parameter mapping (the
`envelope.py` style — construction, age band, insulation type/thickness,
documentary wall thickness), omitting the calculator's rich extras (surveyor
description, dry-lining, lodged `wall_u_value`). The omissions bias the gate
toward OFFERING — both sides are computed identically, so a genuine no-op still
compares equal — never toward suppressing a real measure.
"""
from typing import Any, Final, Optional
from datatypes.epc.domain.epc_property_data import SapBuildingPart
from domain.sap10_ml.rdsap_uvalues import WALL_UNKNOWN, Country, u_wall
# Improvements below this are float noise, not a physical change. NOT a
# materiality threshold — how much improvement is worth the cost stays with the
# Optimiser (ADR-0016/0024).
_NOISE_FLOOR_W_PER_M2K: Final[float] = 0.01
# RdSAP `wall_insulation_type` 4 = as-built / assumed (no added insulation).
_WALL_INSULATION_NONE: Final[int] = 4
def _int_or_none(value: Any) -> Optional[int]:
return value if isinstance(value, int) else None
def _parse_thickness_mm(value: Any) -> Optional[int]:
if value is None or isinstance(value, int):
return value
if isinstance(value, str) and value.strip().isdigit():
return int(value.strip())
return None # "NI" / free text — thickness not known
def wall_insulation_lowers_u(
main: SapBuildingPart,
country_code: Optional[str],
*,
insulation_type: int,
insulation_thickness_mm: Optional[int] = None,
) -> bool:
"""Whether insulating the main wall to ``insulation_type`` (+ optional
thickness) lowers its derived U-value by more than float noise — the Wall
U-Value Gate (ADR-0051)."""
country: Country = Country.from_code(country_code)
age_band = main.construction_age_band
construction: Optional[int] = _int_or_none(main.wall_construction)
if construction == WALL_UNKNOWN:
construction = None
wall_thickness_mm = main.wall_thickness_mm
current_type: Optional[int] = _int_or_none(main.wall_insulation_type)
current_u: float = u_wall(
country,
age_band,
construction,
_parse_thickness_mm(main.wall_insulation_thickness),
insulation_present=(
current_type is not None and current_type != _WALL_INSULATION_NONE
),
wall_insulation_type=current_type,
wall_thickness_mm=wall_thickness_mm,
)
post_u: float = u_wall(
country,
age_band,
construction,
insulation_thickness_mm,
insulation_present=True,
wall_insulation_type=insulation_type,
wall_thickness_mm=wall_thickness_mm,
)
return current_u - post_u > _NOISE_FLOOR_W_PER_M2K