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2805e13d4d
The 7-cert ASHP+battery PE cluster was overshooting by +2.7..+8.1 kWh/m²
after the PE β-split landed in S0380.45. The handover hypothesised an
E_PV magnitude bug ("cascade thinks 2570 kWh/yr vs worksheet 831"). The
worksheet PDF for cert 0380 (dr87-0001-000899.pdf line 233) was
verified to show **-2563.3692** kWh/yr — matching our cascade. The
real bug was different: the **5-kWh battery wasn't reaching the
cascade**, so β-coefficients used the no-battery branch (C1=1.61,
β≈0.36) instead of the 5-kWh branch (C1=1.12, β≈0.75).
Per SAP 10.2 Appendix M1 §3c-d (p.94): "C_bat is the usable capacity
of the battery in kWh, limited to a maximum value of 15 kWh. C_bat=0
if no battery present." Cert 0380 lodges `pv_battery_count: 1` and
`pv_batteries: [{"battery_capacity": 5}]` — but the schema's
`PvBatteries` dataclass had only `pv_battery: Optional[PvBattery]`,
matching the older synthetic fixture shape (nested
`{"pv_battery": {"battery_capacity": 5}}`). The real-API payload's
flat `battery_capacity: 5` was silently dropped during `from_dict`.
Two surgical changes:
- `datatypes/epc/schema/rdsap_schema_21_0_1.py`: add
`battery_capacity: Optional[float] = None` as a sibling to
`pv_battery` on `PvBatteries`. Synthetic-shape certs continue to
populate the nested form; real-API certs now populate the flat form.
- `datatypes/epc/domain/mapper.py:_first_pv_battery`: prefer nested
when present, fall back to the flat lifted field. Domain still
exposes a single uniform `PvBatteries(pv_battery=PvBattery(...))`
shape downstream.
Cohort impact (PE residual kWh/m² vs worksheet):
| Cert | Pre-S0380.48 | Post-S0380.48 |
|---|---:|---:|
| 0350 | +2.73 | -3.58 |
| 0380 | +8.09 | -4.01 |
| 2225 | +4.48 | -4.50 |
| 2636 | +3.42 | -4.14 |
| 3800 | +3.58 | -4.01 |
| 9285 | +3.20 | -3.46 |
| 9418 | +4.67 | -3.76 |
Cluster magnitude dropped from +2.7..+8.1 to -3.5..-4.5 — the cascade
now over-credits PV by ~4 kWh/m² (vs previously under-crediting by
~5 kWh/m²). The residual flipped sign because cascade β=0.75-0.81
slightly exceeds worksheet β=0.74 (read from page-3 line 233a/233b
ratio 1903.39/2563.37 = 0.7426). The remaining ~4 kWh/m² under-shoot
traces to two structural factors deferred until a fresh closure
slice ships:
1. The synthetic-default `pv_export_primary_factor = 0.501` is the
annual Table 12 code-60 value. The worksheet uses the effective
monthly Table 12e factor weighted by E_PV,ex,m (cert 0380: 0.4268
= -0.074 differential). The cascade's `_effective_monthly_pe_
factor` already computes the same weighting for PV — but the
calculator's PV PE credit reads `inputs.other_primary_factor`
(=1.501) and `inputs.pv_export_primary_factor` (=0.501) directly,
bypassing the per-end-use effective-monthly cascade.
2. Cascade β slightly higher than worksheet (0.751 vs 0.7426 on
cert 0380) — likely a monthly-distribution detail in D_PV.
SAP scores remain exact across the cohort (residual +0 every cert).
CO2 residuals all <0.11 t/yr (well within the 0.001-tolerance pin
range after re-pin). 9501 (PV no battery) preserved at +0.255 PE /
-0.047 CO2 — no regression. Re-pins all 7 golden fixtures in the
same slice per [[feedback-commit-per-slice]].
Pyright net-zero on touched files (32 errors before, 32 after).
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|---|---|---|
| .. | ||
| domain | ||
| loaders | ||
| schema | ||
| search | ||
| surveys | ||
| __init__.py | ||
| construction_age_band.py | ||
| efficiency.py | ||
| floor.py | ||
| fuel.py | ||
| heating_controls.py | ||
| hotwater.py | ||
| main_heating.py | ||
| property_type_built_form.py | ||
| roof.py | ||
| walls.py | ||
| windows.py | ||