Model/tests/infrastructure/epc_client
Khalim Conn-Kowlessar 3f6129afc6 Bill a sheltered wall to a stairwell at Ru 2.1, not the corridor 0.5 🟩
RdSAP 10 §5.9 "U-values of sheltered walls" (PDF p.43): a wall between a
flat/maisonette and an unheated buffer takes SAP 10.2 §3.3's U = 1/(1/U0 + Ru),
and Ru depends on the BUFFER TYPE — "Use Ru = 0.5 m²K/W for corridors and
Ru = 2.1 m²K/W for stairwell."

The buffer type is lodged on `SapFlatDetails.heat_loss_corridor` (0-based per
item 1-11, PDF p.70: 0 none, 1 heated, 2 unheated corridor, 3 unheated
stairwell). That field was read NOWHERE under domain/ — corridor presence was
inferred only from a lodged sheltered alternative wall — so every sheltered wall
took the corridor 0.5 and every stairwell flat over-billed its sheltered wall,
under-rating the dwelling.

Distinct from `_SHELTERED_GABLE_ADDED_RESISTANCE_M2K_W`, which is RdSAP 10
Table 4 (p.22) for a room-in-roof sheltered gable — same 0.5, different rule,
deliberately untouched.

Corpus gauge ratcheted UP: within-0.5 78.8% -> 79.8% (+10 certs), SAP MAE
0.626 -> 0.613, PE MAE 2.9 -> 2.8. Failure set and pyright count identical to
main. Portfolio 824 is stairwell-heavy (60 properties at code 3); property
749898 over-bills 4.44 W/K on a 48 m2 flat.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-07-21 22:02:31 +00:00
..
__init__.py python upgraded due to enum 2026-06-12 15:47:28 +00:00
conftest.py python upgraded due to enum 2026-06-12 15:47:28 +00:00
test_client.py docs(adr): record nearby-postcode broadening (0034) + share HTTP retry primitive 2026-06-23 16:54:06 +00:00
test_mapper_corpus.py python upgraded due to enum 2026-06-12 15:47:28 +00:00
test_mapper_dispatcher.py Unsupported EPC schema versions are skipped with a warning, not a crash 2026-07-10 11:17:07 +00:00
test_pv_battery_sap_neutrality.py test(pv-battery): pin SAP cost-neutrality on export-capable standard tariff 2026-06-14 09:51:34 +00:00
test_sap_accuracy_corpus.py Bill a sheltered wall to a stairwell at Ru 2.1, not the corridor 0.5 🟩 2026-07-21 22:02:31 +00:00