# Autonomous corpus run — findings for review (2026-06-16)

> ## 🚩 MANUAL REVIEW NEEDED — heat-pump fuel code 39 mis-priced (CALCULATOR)
> **Owner action required.** Database heat-pump certs (fuel code 39) are priced
> at the **gas** rate instead of electricity → SAP over-rated by ~14
> (uprn_10093114053: eng 93 vs lodged 79). Root cause + evidence in §"BUGS" below
> and memory `heat-pump-fuel-39-mispriced`. NOT auto-fixable: the correct
> electricity tariff for a database heat pump (standard code 30 vs a heat-pump
> tariff) is a SAP-domain judgement and it touches the Table-12a off-peak split.
> Decide the tariff, then it's a normal TDD fix. Affects every fuel-39 cert.


Triaged the full remaining worklist (~95 UPRNs): capture → map → engine SAP,
flagging |eng−lodged| ≥ 8. Most certs map within ±4 of lodged. The worklist is
fully annotated per-UPRN (schema · eng/lodged · flag).

## Corpus-wide tally (after annotation)
| Bucket | Count |
|---|---|
| Mapped, healthy (within tolerance) | 64 |
| 🚩 **MVHR not credited** (flag B) | **19** ← biggest |
| 🚩 heat-pump fuel-39 (flag A) | 6 |
| ⛔ sparse / NOT MAPPABLE | 4 |
| ⚠ other moderate gap (undiagnosed) | 1 |
| ✅ Elmhurst-pinned | 3 |

## ✅ Schema coverage ADDED this run (low-risk, tested, committed)
- **SAP-18.0.0** → full-SAP shape, dispatched to `from_sap_schema_17_1` (no
  normalisation). Maps fine (e.g. 10094601287 → 80/lodged 84).
- **SAP-16.0** → same reduced-field 16.x path; only omitted `tenure`, now
  defaulted in `_normalize_sap_schema_16_x`. Maps (100020933894 → 61/lodged 56).
- (16.2/16.3/17.0 were added earlier in the session.)

## ⛔ Genuinely SPARSE 16.x certs (insufficient data — cannot score)
Missing 18 required fields incl. core fabric (glazed_area, window, door_count,
habitable_room_count, multiple_glazing_type). Fail loud at from_dict (correct):
- uprn_10090844948 (16.3), uprn_10014314798 (16.2), uprn_10014314853 (16.3),
  uprn_10014314830 (16.2). These are minimal "reduced-data" lodgements.

## 🐞 BUGS FOUND (diagnosed; NOT fixed — for your review)

### 1. Opening dimensions in millimetres read as metres — MAPPER bug (SEVERE) ✅ FIXED
**FIXED** (TDD, `_sanitise_opening_dimension_m` + `_sap_opening_area_m2`): any opening
dimension > 50 m is mm → ÷1000. Applied to windows, roof windows, and the door
area-weighting. The 3 broken certs now score 90 / 81 / 79 (were all 1). 3 RED→GREEN
slices + refactor; fixture sap_17_1_mm_openings.json; 0 new pyright errors.
Original report below.


Full-SAP certs whose `sap_building_parts[].sap_openings[]` lodge width/height in
**mm** (mixed with metre rows in the same array) → the 17.1 mapper treats all as
metres → multi-million-m² windows → HTC in the millions → **SAP clamps to 1**.
- **uprn_10093117227** (eng 1 / lodged 80): opening "Side Elevation" 2025×2100 (mm)
- **uprn_10090317693** (eng 1 / lodged 88): 940×2100, 700×1500 (mm)
- **uprn_10091636031** (eng 1 / lodged 85)
- Fix idea: sanitise `sap_openings` dims in `_sap_17_1_windows`/doors — any
  dimension > ~50 m is impossible → it's mm, ÷1000. Cleanly separates the mm rows
  (1000/2025/2100) from the m rows (3.06/3.6/1). Safe, high-value (3+ certs broken).

### 2. Heat-pump fuel code 39 mis-priced as gas — CALCULATOR bug
- **uprn_10093114053** (eng 93 / lodged 79, +14): PCDB heat pump COP 3.33, fuel 39.
- Code 39 absent from `table_12.UNIT_PRICE_P_PER_KWH` → gas default 3.64p; CO2
  factor correctly electricity (0.136). Inconsistent across price vs Table-12a.
- Affects ALL database heat-pump certs (fuel 39). See memory
  `heat-pump-fuel-39-mispriced`. Needs SAP-domain confirmation of the correct
  electricity tariff (standard 30 vs heat-pump) → not an autonomous fix.

## ⚠ MODERATE gaps — now CLASSIFIED into two patterns

### Pattern A — heat-pump fuel-39 / high-COP certs (= bug #2, both directions)
- uprn_10090342180 (fuel 39): +9 (over-rates, classic fuel-39 mispricing)
- uprn_10093388053 (fuel 39): −7   ·  uprn_100090108846 (fuel 29 HP, COP 3.44): −15
- All resolve once the heat-pump fuel pricing is fixed (🚩 review item above).

### Pattern B — 🚩 MVHR heat recovery NOT modelled — CALCULATOR gap (NEW, REVIEW)
Full-SAP **gas** certs that UNDER-predict −6…−12 ALL carry an **MVHR system index**
(`mechanical_vent_system_index_number` 500352 / 500230 / 500438 …). MVHR recovers
exhaust heat (big SAP boost), but the engine models mechanical ventilation as
**extract heat loss, not heat recovery** (same as the worked-ref note: "decentralised
MEV → EXTRACT_OR_PIV_OUTSIDE, priced as extract loss"). So every MVHR cert is
systematically under-credited.
- uprn_10090343767 (−12), 10090341811 (−9), 10093386427 (−9), 202211170 (−7),
  10091636116 (−8), 10093049867 (−6), 10090034761 (−6), 10091636031 (−6).
- Needs the SAP Appendix Q / PCDB MVHR heat-recovery efficiency model — a feature,
  not a one-line fix. See memory `mvhr-heat-recovery-not-modelled`.

### Other
- uprn_100061086424 (RdSAP-17.0, fuel 29, −15): not yet diagnosed (off-peak electric).

## NOT diagnosed individually
The ~70 within-±4 certs are not listed; they look healthy.