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The SAP/EI rating is computed on UK-average weather (Appendix U Tables U1-U3 region 0) so ratings are nationally comparable, but Appendix U paragraph 1 (PDF p.124) requires that "other calculations (such as for energy use and costs on EPCs) are done using local weather. Weather data for each postcode district are taken from the PCDB". `Sap10Calculator. calculate` ran ONE cascade (UK-average) and fed it to SAP, CO2 AND primary energy, so every cert's EPC-displayed CO2/PE were computed on the wrong climate. Because most of England is warmer than the UK-average, this systematically OVER-counted heating demand on the emissions/PE outputs. The two cascades (`cert_to_inputs` rating, `cert_to_demand_inputs` postcode) already existed; this wires the demand cascade into the production entry point and grafts its CO2/PE onto the rating result (SAP unchanged). The corpus gauge's longstanding +5% CO2/PE over-estimate was mostly this climate bug, NOT (as previously diagnosed) per-cert mapper fidelity: CO2 MAE 0.26 -> 0.12 t/yr (bias +0.18 -> +0.04) PE MAE 13.6 -> 3.8 kWh/m2 (bias +9.0 -> +0.24) SAP within-0.5 = 69.7% (rating cascade, unchanged) Worksheet-validated to 1e-4 on simulated case 45 (heat-pump ground-floor flat, postcode W6): the P960 prints the current dwelling twice — Block 1 on UK-average weather (SAP 60.5318, CO2 692.13) and Block 2 on postcode weather (CO2 626.78, PE 6581.59). Both reproduce exactly. Added a tracked case-45 Summary fixture + two-cascade cascade pin as a permanent guard, and ratcheted the corpus CO2/PE ceilings to 0.13 / 4.2. The e2e Elmhurst suite (Block-1 line refs) now pins the rating cascade directly; the two Vaillant overlay snapshots refreshed to demand-cascade CO2/PE. pyright not installed in this codespace (strict gate not run locally); change is type-trivial (dataclasses.replace over SapResult). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> |
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| .. | ||
| handler | ||
| tests | ||
| __init__.py | ||
| db_writer.py | ||
| elmhurst_extractor.py | ||
| extractor.py | ||
| local_runner.py | ||
| parser.py | ||
| pdf.py | ||