Model/backend/documents_parser
Khalim Conn-Kowlessar a7894b1185 Slice S0380.92: AP4 + MEV decentralised plumbing (SAP 10.2 §2 (17a)/(18)/(23a)/(24c))
SAP 10.2 §2 lines (17a)/(18) "Air permeability value, AP4 (m³/h/m²)"
(PDF p.12-13):

> "The air permeability at 4 Pa (AP4) measured with the low-pressure
>  pulse technique [...] is used in the following formula to estimate
>  of the air infiltration rate at typical pressure differences.
>  In this case (9) to (16) of the worksheet are not used."
>
>   Air infiltration rate (ach) = 0.263 × AP4^0.924
>
>   If based on air permeability value at 4 Pa,
>   then (18) = [0.263 × (17a)^0.924] + (8)

SAP 10.2 §2 lines (23a)/(24c)/(25) "MEV" + "Whole-house extract
ventilation" (PDF p.13/133):

> "The SAP calculation is based on a throughput of 0.5 air changes per
>  hour through the mechanical system."  (23a) = 0.5
>
>   If whole house extract ventilation or positive input ventilation
>   from outside:
>     if (22b)m < 0.5 × (23b), then (24c) = (23b)
>     otherwise (24c) = (22b)m + 0.5 × (23b)

Cert 000565 lodges:
- Summary §12.1 "Mechanical Ventilation Type: Mechanical extract,
  decentralised (MEV dc)" (PCDF 500755)
- Summary §12.2 "Test Method: Pulse" + "Pressure Test Result (AP4): 2.00"

Pre-slice both lodgements were silently dropped by the Elmhurst
extractor / mapper / `cert_to_inputs` cascade:

- AP4 had no schema field on `VentilationAndCooling` or `SapVentilation`
  even though `ventilation.py:ventilation_from_inputs(air_permeability_
  ap4=...)` already implemented the spec formula.
- Mechanical Ventilation Type had no schema field; `cert_to_inputs.
  ventilation_from_cert` hardcoded `mv_kind=MechanicalVentilationKind.
  NATURAL` regardless of the lodgement, routing cert 000565 through
  the (24d) natural-vent formula instead of (24c).

These bugs are coupled: AP4 alone would close (18) but the cascade's
(25) NATURAL pass-through would then *under*-count the effective ach
by 0.25 (the missing MEV contribution). MEV alone would over-count
because the (18) over-count remains. Per [[feedback-bigger-slices-
for-uniform-work]] + handover precedent on coupling-aware reverts,
these land together.

Slice span (5 layers):
1. **Schema** — `VentilationAndCooling.air_permeability_ap4_m3_h_m2` +
   `VentilationAndCooling.mechanical_ventilation_type` (site-notes);
   `SapVentilation.air_permeability_ap4_m3_h_m2` +
   `SapVentilation.mechanical_ventilation_kind` (domain).
2. **Extractor** — `_extract_ventilation` parses "Pressure Test Result
   (AP4)" scoped to §12.2 and "Mechanical Ventilation Type" scoped to
   §12.1. Both default to None when the cert lodges no MV / no Pulse
   test (cohort modal case).
3. **Mapper** — `_map_elmhurst_ventilation` plumbs AP4 through; new
   `_ELMHURST_MV_TYPE_TO_KIND` dispatch with strict-raise on unmapped
   labels (per [[reference-unmapped-elmhurst-label]] mirror pattern).
4. **cert_to_inputs** — `ventilation_from_cert` reads AP4 and resolves
   `mechanical_ventilation_kind` name → `MechanicalVentilationKind`
   enum. MEV/MV/MVHR kinds set `mv_system_ach=0.5` per spec (23a).
5. **Tests** — 4 in test_summary_pdf_mapper_chain.py (extractor + mapper
   for both AP4 and MEV kind), 2 in test_cert_to_inputs.py (cascade
   AP4 formula + MEV kind dispatch). All AAA-structured.

Cert 000565 movement (HEAD `83218630` → this slice):
  - cascade (18) pressure_test_ach:  2.4037 → 2.0287 ✓ EXACT vs ws 2.0287
  - cascade (21) shelter-adj:        2.0431 → 1.7244 ✓ EXACT vs ws 1.7244
  - cascade mean (25)m:              2.2347 → 2.1360 vs ws 2.086 (+0.05)
  - **sap_score (integer):           28     → 29 ✓ EXACT vs ws 29** (Δ−1 → Δ 0)
  - sap_score_continuous:            27.99  → 28.77 (Δ−0.52 → +0.26)
  - ecf:                             5.44   → 5.36  (Δ+0.05 → −0.03)
  - total_fuel_cost_gbp:             4726.75 → 4657.37 (Δ+46 → Δ−23)
  - co2_kg_per_yr:                   6506.48 → 6415.56 (Δ+59 → Δ−32)
  - **space_heating_kwh:             +631   → −367**   (~75% closed)
  - main_heating_fuel:               +371   → −216    (~58% closed)
  - hot_water_kwh:                   ✓ 0 EXACT unchanged
  - lighting / pumps_fans:           sub-spec residuals unchanged

The residual cascade-over-by-0.05 ach on (25)m is the cascade using
the cert-agnostic Table U2 wind tuple instead of the cert's regional
wind lookup; future ventilation_from_cert wires a `postcode_climate`
arg through which `cert_to_demand_inputs` already does for the demand
cascade, but the SAP-rating cascade keeps the Table U2 default.

Cohort safety:
- All 21 other Elmhurst cohort fixtures lodge `pressure_test_method=
  "Not available"` and `mechanical_ventilation=False` → both new
  fields default to None → cascade behaviour unchanged.
- 9 golden + 38 cohort-2 API certs route through `_map_sap_ventilation`
  (the API mapper variant), which leaves both new SapVentilation
  fields at their None default → cascade behaviour unchanged.

Test baseline: 582 pass + 8 expected `000565` fails (was 575 + 9; +6
new tests + sap_score reclassified from fail to pass). 1763 pass in
broader sap10_ml + worksheet + epc.domain suites + 3 pre-existing
fails unchanged. Pyright net-zero per touched file (1/0/0/32/34→32/13/
11 → 1/0/0/32/32/13/11, cert_to_inputs.py improved −2).

Per [[project-sap10_ml-deprecation]] the new fields live on the
existing `SapVentilation` domain type; no new modules under sap10_ml.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-30 13:29:50 +00:00
..
handler address JTK review comments 2026-04-20 15:11:17 +00:00
tests Slice S0380.92: AP4 + MEV decentralised plumbing (SAP 10.2 §2 (17a)/(18)/(23a)/(24c)) 2026-05-30 13:29:50 +00:00
__init__.py Map to RdSapSiteNotes from site notes JSON 🟥 2026-04-16 13:54:03 +00:00
db_writer.py include updating epc_property_data to pashub to ara workflow 2026-04-29 09:55:14 +00:00
elmhurst_extractor.py Slice S0380.92: AP4 + MEV decentralised plumbing (SAP 10.2 §2 (17a)/(18)/(23a)/(24c)) 2026-05-30 13:29:50 +00:00
extractor.py Handle wall thickness "Unmeasurable" 🟩 2026-04-30 16:41:16 +00:00
local_runner.py update local runner to work for elmhurst 2026-04-24 14:01:36 +00:00
parser.py load ecmk site notes to db 2026-04-29 11:20:47 +00:00
pdf.py update local runner to work for elmhurst 2026-04-24 14:01:36 +00:00