`u_window` hard-coded the 12 mm gap row for pre-2002 double/triple glazing
(double 2.8, triple 2.1), ignoring the lodged glazing gap. Table 24 splits
the pre-2002 rows by gap: double 6mm=3.1 / 12mm=2.8 / 16mm+=2.7; triple
6mm=2.4 / 12mm=2.1 / 16mm+=2.0 (PVC/wooden), with a metal-frame column
(+0.5/+0.5/+0.5 ish). Added a `glazing_gap` parameter + `_glazing_gap_row`
helper and wired `w.glazing_gap` through the synthesised-window caller in
heat_transmission.
Corpus impact nil by design: the gov-API mapper already resolves per-window
U gap-aware via `_API_GLAZING_TYPE_GAP_TO_TRANSMISSION` (e.g. code 3 + gap
"16+" → 2.7), so corpus certs use that lodged per-window U, not this fallback.
This aligns the reduced-field / worksheet fallback path with the mapper and
Table 24. Unknown gap still defaults to the 12 mm row.
(Metal frames are not distinguishable on the gov-API path — only a `pvc_frame`
boolean exists and Table 24 groups PVC+wooden — so the PVC/wooden U stands
there; the metal column applies only where frame material is lodged.)
Spec-pinned: pre-2002 double + triple gap-row tests. pyright not installed.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The flat floor-exposure heuristic keys on dwelling_type: a flat defaults
to has_exposed_floor=False (assuming a heated dwelling below). The
Elmhurst Summary path lodges a ground-floor flat's vertical position as a
"Ground floor" floor_type rather than the API floor_heat_loss=1 exposed
code, and the mapper can label such a flat "Top-floor flat" — so the
cascade dropped the ground floor entirely (a ground floor is in contact
with the ground and carries heat loss).
Treat a "ground floor" floor_type as a heat-loss floor, overriding the
dwelling-level suppression upward — mirroring the existing "another
dwelling below" party override downward.
Worksheet-validated to 1e-4 on simulated case 45 (a ground-floor flat
the mapper labelled "Top-floor flat"): floor (28a) 0 -> 25.38 W/K,
fabric (33) 75.63 -> 101.0104, HTC (39) 112.93 -> 145.3579, all matching
the P960 exactly; SAP 67.81 -> 62.52. RdSAP-21.0.1 corpus within-0.5
69.5% -> 69.7% (MAE 0.859 -> 0.854). Floors ratcheted. Pinned in
test_heat_transmission (ground-floor billed + party-floor suppressed).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The deduplicated `epc.roofs[]` list cannot be indexed 1:1 against the
building parts (190/329 multi-part certs have len(roofs) != len(parts)),
so every part's `u_roof` consumed a SINGLE join of all roof descriptions.
That leaked one part's insulation state onto another: a "Flat, no
insulation" extension dragged a "Pitched, insulated (assumed)" main roof
to the uninsulated 2.30, ~3x over-stating its heat loss. 3-part certs
systematically under-rated (56% within-0.5, mean -0.79 SAP).
Partition the non-RR roof descriptions into flat vs pitched/sloping and
match each part to its own kind (`_main_roof_descriptions_by_kind`),
falling back to the global join when a part's kind has no matching entry.
Corpus cert 100010129331: roof 110.5 -> 31.3 W/K, +13.10 -> -0.05 SAP.
RdSAP-21.0.1 within-0.5 68.8% -> 69.5% (MAE 0.888 -> 0.859; PE 13.9 ->
13.6); 3-part cohort 56% -> 61%. Floors/ceilings ratcheted. Pinned in
test_heat_transmission (by_kind split + mixed-roof no-contamination).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Close the §6.1 conservatory demand cascade per RdSAP 10 §6.1 + Table 25.
Solar gains (§6, solar_gains.py) — Table 25 note (PDF p.51): "The
orientation of windows in a conservatory is not recorded, thus solar
gains are calculated using the default solar flux (East/West orientation,
with 20° pitch for roof windows)." The glazed wall bills onto the (76)
East line (vertical, average-overshading Z); the glazed roof onto the
(82) roof-window line (20° pitch, Z=1.0), both at Table 25 g=0.76, FF=0.70.
TFA-occupancy (mapper) — §6.1: the conservatory floor area is added to the
dwelling total floor area. TFA drives occupancy → §5 internal gains + §4
hot-water demand, so the non-separated conservatory's floor area now
enters `EpcPropertyData.total_floor_area_m2` (the worksheet's (4) = 95.38
carries it). Separated conservatories (§6.2) stay excluded.
Pinned against the case-44 P960 demand cascade at abs=1e-4: (73) internal
gains 625.1759, (83) solar gains 495.8655, (95) useful gains 1079.6510,
(99) space heating per m² 89.8073 — the full §6.1 chain reproduces EXACTLY.
The whole-dwelling SAP (72.9517) / CO2 (3241.8656) are not pinned: the
case-44 Summary omits the House-Coal secondary heater (SAP 633) the P960
descriptor carries (cf. case 43), so the cascade computes no secondary —
the entire residual (+349.77 kg CO2). A Summary-input defect, independent
of §6.1; every conservatory-affected line ref is exact. Worksheet harness
stays 47/47 0-raised; corpus unchanged (API path; mirror is the next slice).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
SAP-Schema-16.2 (datatypes/epc/domain/mapper.py):
- 16.2 is structurally an RdSAP-17.1 cert under a different name; add
_normalize_sap_schema_16_2 (field renames + defaults) and dispatch to the
tested from_rdsap_schema_17_1 mapper. uprn_100020933699 maps → SAP 71.
- Honour a "Single glazed" windows description when multiple_glazing_type="ND"
(was defaulting to double) → RdSAP-21 code 5; eng 72→71 (lodged 70).
- 4 regression tests + sap_16_2.json fixture; 0 new pyright errors.
Flat party-wall fix (domain/sap10_calculator/worksheet/heat_transmission.py):
- Full-SAP flats carry flatness in dwelling_type, not property_type, so the
party-wall default fell through to the 0.25 house value instead of the RdSAP
Table-15 flat 0.0. Add _is_flat_or_maisonette_dwelling fallback + regression
test. uprn_10093116529 80→81 (matches the cert's lodged party u_value 0).
Accuracy corpus pins (tests/domain/sap10_calculator/test_real_cert_sap_accuracy.py):
- uprn_10093116543 (SAP-17.1 gas-combi semi): engine 81 (Elmhurst 77; documented
full-SAP→RdSAP residual — measured wall/floor U + PCDB boiler vs RdSAP defaults).
- uprn_10093116529 (SAP-17.1 g/f flat): engine 81 (Elmhurst 78).
devcontainer: add poppler-utils (pdfinfo) for the documents-parser PDF fixtures.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Wire the non-separated conservatory into the §3 heat-transmission +
§1 dimensions cascade per RdSAP 10 §6.1 (PDF p.49) + Table 25 (p.51):
"The floor area and volume of a non-separated conservatory are added to
the total floor area and volume of the dwelling. Its roof area is taken
as its floor area divided by cos(20°), and wall area is taken as the
product of its exposed perimeter and its height. ... The conservatory
walls and roof are taken as fully glazed ... Glazed walls are taken as
windows, glazed roof as rooflight."
New `worksheet/conservatory.py` derives the geometry:
- height from the equivalent storey count (§6.1: 1 storey → ground-floor
room height; 1½ → ground + 0.25 + 0.5×first; etc.);
- glazed WALL → window (27) at Table 25 U (double 3.1 / single 4.8) with
the §3.2 curtain resistance (R=0.04) → U_eff 2.758;
- glazed ROOF → rooflight (27a) at Table 25 roof U (double 3.4 / single
5.3) + curtain → U_eff 2.993;
- FLOOR → (28a) via BS EN ISO 13370 as an uninsulated SOLID ground floor
with 300 mm walls (§5.12, spec p.43), exposed perimeter = glazed
perimeter → U 0.89;
- glazed wall + roof + floor areas join (31)/(36); the fully-glazed
structure walls/roof add nothing (the glazing IS the window/rooflight).
`dimensions_from_cert` adds the conservatory floor area to TFA (4) and
floor area × height to volume (5) (feeds ventilation (8)), without making
it a storey (avg storey height for §2 infiltration is unchanged).
Pinned against the simulated case-44 P960 §3 at abs=1e-4 — every line ref
EXACT: (4) 95.3800, (5) 257.1630, (27) 96.1169, (27a) 38.2201, (28a)
21.4164, (29a) 35.5852, (30) 7.4688, (31) 294.2900, (33) 207.3274,
(36) 23.5432. The remaining whole-dwelling SAP/CO2 gap is the §6 solar
gains, closed in the next slice. Worksheet harness stays 47/47 0-raised.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The gov API lodges a manufacturer's declared cylinder loss factor
(kWh/day) in `sap_heating.cylinder_heat_loss`, in which case it leaves
the cylinder volume / insulation type / thickness None. That field was
undeclared on the 21.0.x schemas, so `from_dict` dropped it — then
`_cylinder_storage_loss_override` hit its insulation-None / volume-None
guards and returned None, dropping the §4 storage loss ENTIRELY. The
dwelling over-rated (the declared loss is typically ~1.5 kWh/day ≈
550 kWh/yr).
SAP 10.2 §4 branch a) (PDF p.136): when the declared loss factor is
known, storage loss (50) = (48) declared loss × (49) Table-2b
temperature factor — replacing the Table 2 V×L×VF computation.
- declare `cylinder_heat_loss` on RdSapSchema21_0_0/21_0_1.SapHeating +
EpcPropertyData.SapHeating; thread through the 21.0.x mappers.
- `cylinder_storage_loss_monthly_kwh` gains `declared_loss_kwh_per_day`:
when set, combined_55 = declared × TF (volume/insulation unused).
- `_cylinder_storage_loss_override` resolves the declared loss BEFORE the
insulation/volume guards (the gov omits those when the loss is lodged).
12 /tmp certs carry it (mean |err| 3.00 -> 2.51; the clean ones close
hard, e.g. 2360 2.65 -> 0.30, 0245 2.25 -> 0.53). Corpus within-0.5
67.0% -> 67.3% (MAE 1.025 -> 1.020); /tmp 71.2% -> 71.4% (0.889 ->
0.882). Worksheet harness 47/47; regression = only the 3 pre-existing
fails; pyright net-zero.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Roofs lodged insulated at rafters carry their thickness in a DEDICATED
gov-EPC API field, `rafter_insulation_thickness` (e.g. "225mm"), while
`roof_insulation_thickness` stays None (rafters aren't loft joists). That
field was undeclared on the 21.0.x schemas, so `from_dict` silently
dropped it — the rafter certs only *looked* redacted (roof EER 2-4 =
insulated, yet no thickness), and the cascade fell to the Table 18 col (2)
unknown default (2.30), badly under-rating them.
- declare `rafter_insulation_thickness` on RdSapSchema21_0_0/21_0_1 +
EpcPropertyData.SapBuildingPart (mirrors the existing
sloping_ceiling_/flat_roof_insulation_thickness dropped-field handling).
- thread it through `from_rdsap_schema_21_0_0/21_0_1` (older schemas get
None via getattr).
- `heat_transmission` prefers `rafter_insulation_thickness` over
`roof_insulation_thickness` when the part is at-rafters, so the measured
RdSAP 10 §5.11.2 Table 16 column (2) row applies (225 mm → 0.25).
Completes the rafters roof fix: with the real thickness read, the rafter
certs are recovered rather than over-stated — cert 3100-8675-0922-8628
(band E, rafters 225mm) +8.93 → +0.43 SAP. Corpus within-0.5 67.0%
(MAE 1.025) and /tmp 71.2% (MAE 0.889) — both NET ABOVE the pre-rafters
baseline (66.9% / 70.6%). Worksheet harness 47/47; regression = only the
3 pre-existing fails; pyright net-zero.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
`u_roof` only implemented the joist column, so roofs lodged insulated at
rafters (`roof_insulation_location == 1`) were mis-billed at the joist U
on both the API and Summary paths — under-stating loss, over-rating SAP.
RdSAP 10 §5.11.2 Table 16 (spec p.42-43) gives a distinct "insulation at
rafters" column (2): the rafter cavity is shallower than a loft void, so
the same depth yields a higher U (200 mm: rafters 0.29 vs joists 0.21).
§5.11 Table 18 (p.45) likewise carries a rafters column (2) for unknown /
as-built thickness (footnote (1): "The value from the table applies for
unknown and as built") — band A-D = 2.30, E = 1.50, F = 0.68, diverging
from the joist column's 100 mm-equivalent 0.40 default (footnote (4)).
- add `_ROOF_RAFTERS_BY_THICKNESS` (Table 16 col 2) + `_ROOF_RAFTERS_BY_AGE`
(Table 18 col 2) to rdsap_uvalues; `u_roof` selects them via a new
`insulation_at_rafters` flag (ignored for flat / sloping-ceiling roofs).
- `heat_transmission` derives the flag PER BUILDING PART from
`roof_insulation_location` (gov-API int 1 / Summary "R Rafters"), which
also fixes the multi-part dedup-roof-join problem: each part's own
location now drives its U, replacing the unattributable joined
`epc.roofs[]` description.
Worksheet-validated to 1e-4: simulated case 41 (4-bp — Ext1 rafters 200mm
→ 0.29, Ext3 rafters As-Built band F → 0.68; roof total 24.8350) and case
42 (6 variants — rafters 50mm → 0.88, rafters unknown band C → 2.30,
joists/none unchanged). Case 40 stays exact (roof 35.340, total 441.1606);
worksheet harness 47/47.
Corpus within-0.5 66.9% → 66.5% (gates 0.65/1.08 hold) — a spec-correct
shift, NOT a regression: all 15 corpus rafter certs carry redacted (None)
thickness yet lodge roof EER 2-4 (insulated), so the open API blanked a
specified thickness and the spec's unknown-rafter 2.30 default correctly
over-states them. Recovery needs a roof-EER→thickness inference on the
API path (follow-up), not a change to the U-table.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Reduced-field window U: heat_transmission derived the synthesised-window
raw U from u_window(all None) -> the 2.5 placeholder regardless of glazing.
Now routes the (uniform) glazing_type code through u_window (RdSAP Table 24)
so e.g. double pre-2002 reads 2.8, not 2.5. Only the pre-SAP10 reduced-field
path is affected (21.0.1 certs carry per-window U upstream) — the RdSAP-21.0.1
corpus gauge is unchanged at 66.9% within-0.5.
test_real_cert_sap_accuracy: pin uprn_10002468137 (RdSAP-17.1, all-electric
storage heaters) at SAP 61, validated against Elmhurst on identical inputs
(dual off-peak immersion, 110 L cylinder, 2 baths). Our engine reproduces
Elmhurst's fuel cost to the penny; lodged 55 is the old SAP-2012 schema.
Tooling to grow the accuracy corpus:
- scripts/fetch_real_life_epc_sample.py — capture a cert by UPRN into the corpus.
- scripts/compare_epc_paths.py — diff gov-API vs Elmhurst-summary EpcPropertyData
and run both through the engine, localising mapper vs calculator differences.
- skill validate-cert-sap-accuracy — the end-to-end loop (capture -> Elmhurst
inputs -> human builds -> compare -> reconcile -> pin in the test).
- skill epc-to-elmhurst-rdsap-inputs reference: corrected immersion (code 1=dual),
cylinder size (code 2 = Normal/110 L), and bath-count (WWHRS sub-tab) mappings.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The mixer-shower hot-water demand (worksheet 42a) divided N_shower by the
count of MIXER outlets only. But SAP 10.2 Appendix J step 1a is explicit:
"Establish how many shower outlets are present in the dwelling, Noutlets
(including in the count any instantaneous electric showers)" — and the
electric-shower step (64a) uses that same Noutlets from step 1a. So a
dwelling with both a mixer and an electric shower assigned the FULL N_shower
to the mixer system AND billed the electric shower on top of it, double-
counting shower demand → over-counted main HW → under-rated the dwelling.
Fix: thread the electric-shower count into the mixer demand so the
denominator is the total outlet count (mixer + electric), iterating the
warm-water draw over the mixer outlets only (per step 1e).
shower_types=1,2 cohort: -0.37 median -> +0.28 (crossed zero); API gauge
68.4% -> 69.0% within-0.5. Golden cert 0300-2747 (1 mixer + 1 electric)
re-pinned: PE +0.93 -> -0.10, CO2 +0.25 -> +0.15 (both toward zero,
confirming the double-count). Worksheet harness 47/47, 0 divergers (the
Elmhurst fixtures have no electric showers).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The gov-EPC API surfaces the assessor's RdSAP-assessed per-element U-values
as `roof_u_value` / `wall_u_value` / `floor_u_value` on each building part.
These were undeclared on the RdSAP 21.0.0/21.0.1 schemas, so `from_dict`
silently dropped them, and `heat_transmission` re-derived each U from the §5.6
/§5.7/§5.11 construction-default cascade. The gov OPEN data routinely redacts
the backing insulation thickness, so that re-derivation mis-bills an insulated
element as uninsulated.
RdSAP 10 §5.1: a known element U-value (documentary evidence / the lodged
RdSAP output) is used directly in place of the construction-default cascade.
Per [[project_per_cert_mapper_validation_state]] the gov API carries RdSAP
OUTPUT, so the lodged U reproduces the official's element heat loss exactly.
Worst case in the 2026 sample: cert 7921-0052-0940-5007-0663, an age-C
"Pitched, sloping ceiling" (rc=8) top-floor flat lodging roof_u_value=0.2 with
no thickness. The cascade returned the uninsulated 2.30 W/m²K → SAP 56.9 vs
lodged 80 (-23.09, the single largest error in the sample). The roof override
alone recovers ~15 SAP; the wall override (lodged 0.34 vs cascade) closes the
rest of this cohort.
Override applies to the MAIN wall only (alt-wall sub-areas keep their own
per-area U) and the part's floor=0. Fires only when the rare field is present
(9 of 909 computed certs), so the Summary path — which never lodges these
API fields — is untouched.
API gauge: 67.1% → 67.7% within-0.5, mean|err| 1.024 → 0.992.
Worksheet harness: 47/47, 0 divergers (unchanged).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The main-wall `u_wall(...)` call dropped the `dry_lined` kwarg, so the RdSAP 10
§5.7/§5.8 (PDF p.40-41) Table 14 dry-lining adjustment — U_adj = 1/(1/U₀ +
0.17) for a dry-lined (incl. lath-and-plaster) uninsulated wall — was never
applied to any main wall, even when the cert lodged `wall_dry_lined=Y`. The
ALTERNATIVE-wall path already passes `dry_lined` (line 1367); this one-sided
omission billed every dry-lined main wall at the un-adjusted (too-high) U →
wall heat loss too high → SAP under-rated.
Per-cert: a solid-brick (construction 3) band-A 230 mm main wall computes
U₀=1.70; dry-lined it is 1/(1/1.70+0.17)=1.32 — we were 22% too high. Across
the API gov-EPC sample the dry-lined `wall_construction=3` (solid brick)
sub-cohort sat at 10% within-0.5 / signed -1.33.
Fix: pass `dry_lined=bool(part.wall_dry_lined)` to the main-wall `u_wall`
call, mirroring the alt-wall path. `part.wall_dry_lined` is already plumbed
(Optional[bool], None → False). The three dry-lining branches in `u_wall`
(stone §5.6, solid-brick-by-thickness §5.7, generic uninsulated bucket §5.8)
are all spec-correct and already worksheet-validated (the bucket-0 cavity
case against cert 7700 age-C → 1.20).
Worksheet harness UNAFFECTED (47/47, 0 divergers): the Elmhurst/Summary
extractor only captures dry-lining for ALTERNATIVE walls (Summary §7), never
the main wall, so `part.wall_dry_lined` stays None on that path — this is a
pure API-path improvement. API gauge: within-0.5 60.1% -> 64.4% (mean|err|
1.163 -> 1.085, signed -0.097 -> +0.049). Both affected buckets improved
with no overshoot: solid brick (wc=3) 50% -> 57% within-0.5; cavity (wc=4,
dry-lined via the §5.8 bucket-0 path) 68% -> 72%.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A door opening to an unheated corridor/stairwell takes U=1.4 W/m²K (RdSAP 10
Table 26, p.51 — any age band) instead of the 3.0 external-door default, and
its area deducts from the SHELTERED wall, not the main wall (RdSAP §3.7,
p.18: "the door of a flat/maisonette to an unheated stairwell or corridor
... is deducted from the sheltered wall area"). The cascade previously
billed every door at the external U on the main wall.
Signal: a SHELTERED alternative wall (`is_sheltered`, the RdSAP §5.9
wall-to-unheated-corridor surface, already modelled) is the evidence that
the dwelling is accessed via an unheated corridor, so one lodged door opens
to it. `_corridor_door_count` returns 1 when a sheltered alt wall is present
and >=1 door is lodged, else 0 — so the door channel is unchanged for every
non-corridor dwelling (houses, exposed-gable flats). `heat_transmission_
from_cert` gains a `corridor_door_count` param (default 0): it splits the
door area into external (main wall, age-default U) + corridor (sheltered
alt wall, U=1.4), threading the corridor door's area into that wall's
opening deduction and billing it at 1.4.
Validated on TWO faithful worksheets: simulated case 34 (cert 001431
storage flat — doors 8.14 exact, fabric 207.47 ≈ ws 207.48) and the
long-standing worksheet-harness diverger cert 2474 (−0.87 → −0.32, the
"space-demand thread" was the dropped corridor door). The worksheet harness
is now 47/47 with ZERO divergers.
API SAP gauge: 57.6% → 60.0% within 0.5; mean|err| 1.185 → 1.167; signed
−0.165 → −0.115 — ~22 sheltered-corridor flats were a systematic gap.
Regression gate green (3 pre-existing fails unrelated); pyright net-zero.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
SAP 10.2 Table 3 (PDF p.160) verbatim: "For heat networks apply the
formula above with p = 1.0 and h = 3 for all months." The primary
circulation hours for a heat-network main are fixed at h=3 winter and
summer, independent of the cylinder-thermostat / separate-timing
lodgement that selects the h=5/h=11 rows for boiler systems.
`primary_loss_monthly_kwh` / `primary_circuit_hours_per_day_table_3` gain
a `heat_network` flag (→ (3, 3)); `_primary_loss_override` passes
`_is_heat_network_main(main)`. p=1.0 was already pinned via
`_HEAT_NETWORK_PIPEWORK_INSULATION_FRACTION`; only the hours were wrong.
Before, cert 8536 routed through the h=5/3 row because its community
biomass DHW fuel (31) collides with electricity code 31, so
`_separately_timed_dhw` returned False. The Table 3 heat-network rule
overrides that path: 8536 primary loss (59) 335.81 → 273.90, EXACT to
the faithful case-32 worksheet (storage (56) 376.58 also matches 376.94).
API eval within-0.5 57.0% → 56.9% (one offsetting-error cert crosses
out; signed err −0.205 → −0.202). Applied spec-uniformly per the
determinism principle — the heat-network primary hours are unambiguous.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Audit of the API-SAP error (53% within 0.5) localised the systematic
under-rate to ELECTRIC FLATS (houses sit at 60-66% within 0.5; electric
flats 13-19%). Decomposing the flat error showed it tracks space-heating
demand per m² — the worst certs reach 130-289 kWh/m² (accurate certs sit
at 14-110), i.e. a grossly over-stated fabric heat loss, amplified ~4x by
the electricity unit price and the steep low-band SAP log curve.
Root cause: the gov-EPC API lodges `sheltered_wall="Y"` on alternative
wall sub-areas (a sub-area adjacent to an unheated buffer — stair core,
adjoining structure), but the field was dropped by the schema + domain
dataclasses and the calculator billed the alt sub-area at its full
exposed U. RdSAP 10 Table 4 (PDF p.22) "Sheltered": such a wall carries
an added external surface resistance R=0.5 m²K/W → U_sheltered =
1/(1/U + 0.5) — the SAME adjustment the main wall already applies for
`gable_wall_type=2` (`gable_wall_sheltered`,
`_SHELTERED_GABLE_ADDED_RESISTANCE_M2K_W`). Cert 0340-2976 (band-A flat,
42 m² sheltered timber-frame alt) over-stated its wall channel by
~58 W/K → walls 128 -> 70 W/K.
Threads the field end-to-end: schema dataclasses (21.0.0/21.0.1) +
domain `SapAlternativeWall.is_sheltered` (default False — the Summary/
Elmhurst path leaves it False, sheltering rides through its lodged
U-value there, so goldens are untouched) + `from_api_response` mapping
`"Y"->True` + `_alt_wall_w_per_k` applying the 0.5 resistance on the
cascade path (lodged-U and basement alt-walls return before it).
140 certs (15% of the corpus) carry a sheltered alt-wall; they under-
rated at median -0.82 / mean signed -1.33 / 23% within 0.5. Eval: 102
improved, 38 regressed (offsetting-error cases — fix is spec-uniform per
[[feedback_software_no_special_handling]]); within-0.5 53.14% -> 54.24%,
within-1.0 67.99% -> 69.64%, within-2.0 81.85% -> 83.50%, mean|err|
1.312 -> 1.248, 909 computed / 0 raises. Goldens (6035, 000565) and full
calc/epc/parser regression green; pyright net-zero.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The API `floor_heat_loss` code is authoritative — confirmed by joining each
single-BP cert's code to its independent `floors[].description` (which the
gov register publishes alongside the code):
code 1 ↔ "To external air" (exposed, 9/9)
code 2 ↔ "To unheated space" (semi-exposed, 6/6)
code 3 ↔ "(other premises below)" (partially htd, 9/9)
code 6 ↔ "(another dwelling below)" (party, 176/176)
code 7 ↔ "Solid"/"Suspended …" (ground, all)
Code 3 was mis-mapped to "To unheated space" (semi-exposed) and, on
mid-/top-floor flats, had its floor area zeroed entirely by the
dwelling-level exposure heuristic. RdSAP 10 §3.12 (PDF p.25) classes a
flat's floor over non-domestic "other premises … heated, but at different
times" as "above a partially heated space" → the §5.14 (PDF p.47) constant
U=0.7 W/m²K — distinct from semi-exposed (Table 20) and party (no loss).
Fix: the mapper sets `is_above_partially_heated_space` on the floor=0
dimension for code 3 (string → "(other premises below)" for fidelity), and
the heat-transmission step lets that per-BP lodgement override the flat
suppression upward (mirroring the existing exposed / "another dwelling
below" overrides). The cascade already routes is_above_partial → U=0.7.
Re-pins golden cert 7536-3827: its Ext2 (bp3) lodges code 3, but the cert's
lossy `floors[]` summary dropped that description, so a prior agent guessed
"code 3 = ground" (U=1.12) and concluded the residual was an irreducible
"register-rounding" artifact. It was this bug: Ext2 floor U 1.12 → 0.70,
PE -6.1952 → -5.6414, CO2 -0.1639 → -0.1492 (both toward 0), SAP unchanged.
Eval: 909 computed, 45.1% → 45.3% within 0.5, mean|err| 1.702 → 1.659,
<1.0 59.5% → 60.2%. 13 code-3 certs improve (0380 +3.71 → -0.63, 0350
+7.82 → +0.83, 2610 +7.47 → -1.29); the few that overshoot were already
failing and carry independent fabric bugs (9763's walls = 8 W/K for 60 m²).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A mid-/top-floor flat whose lowest floor is lodged as an exposed floor
(API floor_heat_loss=1) had its floor area zeroed by the dwelling-level
exposure heuristic, which keys only on the flat label and defaults
has_exposed_floor=False (assuming the floor sits over another *heated*
dwelling). RdSAP 10 §3.12 (PDF p.25) is explicit:
"Otherwise the floor area of the flat ... is:
- an exposed floor if there is an open space below"
i.e. a flat cantilevered over a passageway IS a heat-loss floor on
Table 20. The per-BP `is_exposed_floor` lodgement is authoritative and
now overrides the dwelling-level suppression upward, mirroring the
existing "another dwelling below" party override (which suppresses
downward). The code-1↔"E To external air" enum is confirmed by the
paired API+Summary worksheet certs (0350, 3800).
Eval: 45.1% → 45.3% within 0.5 (909 computed); cert 3836 +6.79 → +0.77,
5717 +1.31 → -0.07 and 0997 +0.76 → +0.05 cross into <0.5. Two
already-failing under-rated certs (7636, 2241) shift further — both are
dominated by independent cost-side over-counts the exposed floor merely
unmasks (7636 walls = 8.98 W/K for 33.87 m² is the real defect).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The main pitched/flat roof U-value was derived from the JOINED text of
every roofs[] entry. A room-in-roof carries its own §3.9/§3.10 shell
area + U-value cascade (Table 17 / Table 18 col 4), so a multi-roof cert
lodged "Pitched, insulated (assumed) | Roof room(s), no insulation
(assumed)" leaked the RR's "no insulation" marker into the main roof's
u_roof → U=2.30 applied to the WHOLE main roof, ~3x over-stating its heat
loss. This is the 4700-family regular-roof-U leak.
`_joined_main_roof_descriptions` drops "Roof room(s)" entries before the
main-roof u_roof, falling back to the unfiltered join only for pure-RR
dwellings (every entry an RR) to preserve their prior behaviour. The RR
shell U is unaffected (computed separately) — golden 6035 stays green.
RR-leak cluster (18 certs, RR "no insulation" + a non-RR primary roof):
mean |err| 6.14 → 4.85, within-1.0 0 → 8, within-0.5 0 → 3. Eval headline
44.8% → 44.9%, mean |err| 1.851 → 1.824, mean signed -0.152 → -0.081. Two
certs overshoot (other residuals the leak was masking); the spec rule is
applied uniformly.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A floor lodged API floor_heat_loss=6 ("another dwelling below") sits over
another heated dwelling, so it is a party floor with no heat loss (RdSAP
10 §3). The mapper mapped code 6 → None and the heat-transmission step
drove floor exposure solely from the dwelling-level `has_exposed_floor`
flag — which is keyed only on the dwelling_type label and defaults a
"Ground-floor flat" to an exposed floor. So a ground-floor flat above a
basement dwelling kept its full ground-floor heat-loss area.
Map code 6 → "(another dwelling below)" (still != "Ground floor", so the
§5 (12) suspended-timber rule stays inert) and have the cascade suppress
that BP's floor when its floor_type carries the signal, mirroring the
roof's existing "another dwelling above" per-BP party override.
Cert 2115-4121-4711-9361-3686 (ground-floor flat, floor_heat_loss=6):
floor_w_per_k 47.85 → 0; SAP -23.44 → -4.41. Cert 0350-…-6435 -12.38 →
-0.55; 0926-…-9024 -2.35 → -0.82. Eval mean |err| 1.982 → 1.944.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The 2026 API sample raised UnmappedApiCode on `gable_wall_type` 2 (10 certs)
and 3 (4 certs) — the two RR gable variants beyond Party(0)/Exposed(1).
Sim case 21 (an Elmhurst replica of API cert 2818-3053-3203-2655-9204:
gable_wall_type_1=2, gable_wall_type_2=3) lodges them as "Sheltered" and
"Connected", confirming **2=Sheltered, 3=Connected**.
- Mapper: `_API_TYPE_1_GABLE_TYPE_TO_KIND` gains 2 → `gable_wall_sheltered`,
3 → `connected_wall` (U=0, area deducts — already handled).
- Calculator: new `gable_wall_sheltered` branch. The API path lodges no
per-gable U, so the cascade DERIVES it as RdSAP 10 Table 4 (p.22)
Sheltered = 1/(1/U_wall + 0.5) — back-solved + validated against case 21
(U_wall 1.10 → 0.71) and case 20 (1.70 → 0.92). A lodged U (Summary path)
still rides through as an override.
API sample: 14 raises clear → `computed` 882 → 896, `raise:ValueError` 16 → 2.
Summary path unchanged (Sheltered stays `gable_wall_external` + lodged U, so
cert 000487's hand-built fixture is untouched). 2861 pass (lone
test_total_floor_area pre-existing); pyright strict net-zero (32=32 / 12=12).
NOTE: the derived Sheltered U on cert 2818 lands at 0.92 not 0.71 because the
cascade computes its 440 mm solid-brick wall U as 1.70 (the 220 mm default) —
a SEPARATE wall-U-vs-thickness bug (next slice, validated by case 21's 1.10).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Water heating SAP code 909 (electric instantaneous) and 907 (single-point
gas) heat water at the point of use, serving one outlet with no
distribution pipework. Per SAP 10.2 §4 (p.23, l.1416): "'Single-point'
heaters, which are located at the point of use and serve only one outlet,
do not have distribution losses either." So worksheet (46)m = 0 and the
heat-required line collapses to SAP 10.2 worksheet l.7704
(62)m = 0.85 × (45)m + (46)m + (57)m + (59)m + (61)m
= 0.85 × (45)m (all loss terms zero for a no-cylinder system).
`distribution_loss_monthly_kwh` already supported the
`is_instantaneous_at_point_of_use` flag (and its docstring already named
codes 907/909), but `water_heating_from_cert` hard-coded it to False, so
the cascade applied (46)m = 0.15 × (45)m to single-point heaters. That
0.15 distribution loss exactly cancelled the 0.85 reduction, leaving
(62)m = (45)m. On the cat-10 room-heater fixture (ref 001431, code 909)
that over-stated the water fuel (219) as 2082.6250 instead of the
worksheet's 1770.2313, and inflated the (65)m heat gains (692.47 vs
worksheet 442.55) which in turn suppressed space-heating demand.
Thread the cert's existing instantaneous flag (`_INSTANTANEOUS_WATER_CODES`
= {907, 909}) through `_water_heating_worksheet_and_gains` into both the
demand-pass and final `water_heating_from_cert` calls.
Pins (219) water fuel = 1770.2313 at abs 1e-4 via the extractor → mapper →
rating cascade. §4 suite green (2414 passed, 1 skipped); no existing
fixture exercised the 907/909 path. The residual space-heating fuel gap
((211) 11158.59 vs worksheet 11563.17) this exposes is a separate cause —
next slice.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
PR feedback (dancafc): the simplified room-in-roof branch used cryptic
locals. Rename for clarity (behaviour-unchanged; the geom dict keys and
the builder-function locals are untouched):
rr_a_rr -> rr_roof_area (the worksheet's simplified A_RR)
rr_common -> rr_common_wall_area
rr_gable -> rr_gable_area
a_rr_final -> rr_residual_roof_area (leftover roof-going area after
deducting perimeter walls/gables
/rooflights — takes the roof U)
Names now mirror the `rr_*_area_m2` geom keys they read from and say
"area of what". Added a one-line note that `rr_roof_area` is the RdSAP 10
§3.10.1 A_RR. Pyright unchanged; 1087 heat-transmission/cascade-pin tests
pass.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
5 certs in a 2026 API sample raised `KeyError: 'rr_common_wall_area_m2'`
and were blocked from computing. Root cause: `_part_geometry`'s early
return (taken when a building part lodges no sap_floor_dimensions —
e.g. a party-wall-only or RR-only extension as bp[0]) returned only 6 of
the 9 keys the full return exposes, omitting rr_common_wall_area_m2,
rr_gable_area_m2 and cantilever_floor_area_m2. The §3.9 RR contribution
block reads geom["rr_common_wall_area_m2"] / ["rr_gable_area_m2"] for
EVERY part, so the floorless part's truncated dict raised KeyError at
heat_transmission.py:974.
Fix: the early return now exposes all 9 keys, the three RR/cantilever
geometry values defaulting to 0.0 — correct, since a part with no floor
dimensions has no derivable RR shell or cantilever (no floor area).
Pure contract-completion bug; no spec/U-value change.
Regression test pins the invariant directly: a floorless part's
_part_geometry keys must equal a with-floors part's keys. Validated: all
5 certs now compute (4 within ~2 SAP of lodged; the 5th, 8536, has a
separate residual). §4 suite 2393 passed; heat_transmission.py pyright
unchanged at 12, test file at 71.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Second silently-dropped field from the 2130 audit: the schema-21
SapBuildingPart never declared `wall_insulation_thermal_conductivity`, so
`from_dict` discarded it. Captured it through schema 21.0.0/21.0.1 → domain
SapBuildingPart → API mapper, and wired it into u_wall's RdSAP 10 §5.8
documentary-evidence R-value calc (both the solid-brick §5.7/§5.8 path and
the cavity-composite path), replacing the bare 0.04 λ constant with a
resolved λ.
Resolver: absent / "Unknown" → the §5.8 default 0.04 W/m·K (mineral wool /
EPS); a mapped code → its λ; an unmapped integer code RAISES so the enum is
confirmed against a worksheet rather than silently mis-factored (same
incremental-coverage discipline as the glazing-type map). Only code 1
(= the default 0.04) is mapped — the sole observed value (cert 2130 Ext1).
Zero cascade effect today: the λ path fires only for solid-brick/cavity
walls with a *measured* wall thickness, and 2130 Ext1 lodges no wall
thickness, so its conductivity is captured-but-unused; all existing §5.8
certs lodge no conductivity → 0.04 default unchanged. The point is to stop
dropping lodged data and make λ correct when a future cert exercises it.
Suite: 2523 passed (1 pre-existing TFA fail); sap10_ml 237 passed (2
pre-existing stone-formula fails). Zero new pyright errors (46=46).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A "Pitched, sloping ceiling" roof (roof_construction code 8) lodged with
"As Built" insulation (no measured thickness → None) was wrongly routed to
RdSAP 10 Table 18 column (1) "insulation between joists or unknown". A
sloping ceiling has no joist void, so per RdSAP 10 §5.11 roof-input item
5-5 ("Sloping ceiling insulation … unknown / as built → Table 18") and
Table 18 note (b) ("Applies also to roof with sloping ceiling") it takes
column (3) — band F = 0.68, band L = 0.18 (vs col 1 0.40 / 0.16).
Discriminator is the code-8 "sloping ceiling" string only: code-5 vaulted
ceilings stay on column (1) per the 33 cohort-2 "ND" vaulted certs
(S0380.211), and the "NI"/"ND" unknown case is untouched. New
`is_pitched_sloping_ceiling` flag threaded from heat_transmission to
`u_roof`; pre-1950 bands already reach the same col (3) value (2.30) via
the mapper's thickness=0 → Table 16 row-0 override, so the new branch
carries the post-1950 bands where col 1 ≠ col 3.
Worksheet-validated by simulated case 15 (the 7536 replica): our cascade
on its Summary matches the P960 worksheet exactly — roof HLC 29.17 W/K,
cont SAP 65.04 vs 65. Re-pins golden cert 7536: roof 26.77 → 29.17, cont
SAP 69.071 → 68.924, PE -7.0776 → -6.1952, CO2 -0.1875 → -0.1639 (SAP
integer 68, resid +1 unchanged — the remaining +0.92 is a diffuse demand
under-count needing a fully-faithful worksheet). Blast radius: 7536 only.
Suite: 2388 passed, 1 skipped (main); sap10_ml 233 passed + 2 pre-existing
stone-formula failures (out of scope). Zero new pyright errors.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Closes the Ext1 vaulted-roof over-count that S0380.209 exposed on golden
cert 0240-0200-5706. BP2 lodges roof_construction=5 (vaulted ceiling),
roof_insulation_thickness="NI" (parsed to 0), description "Pitched,
insulated (assumed)", band J. The cascade returned U=0.68 — the RdSAP 10
§5.11.4 (p.44) retrofit-50 mm "insulation at joists" row. A vaulted /
sloping ceiling has no ceiling-joist void, so that row does not apply; per
RdSAP 10 §5.11 Table 18 (p.45) it takes the column (1) age-band default
(band J = 0.16).
The arbiter is the cohort, not the spec text alone: 33 cohort-2 certs
lodge "ND" (thickness None) vaulted roofs (roof_construction=5, band D)
that already pin to their dr87 worksheets at U=0.40 = Table 18 col (1) by
falling through the age-band default. 0240's only difference is the "NI"
sentinel (insulation present, unknown thickness) which uniquely hit the
0.68 override. (The S0380.209 note's predicted "cont ≈ 72.31" assumed a
col-3 0.25 value; the cohort's ND vaulted roofs disprove that — they use
col (1), so 0240 lands at cont 72.4617.)
Implementation: new `u_roof(is_sloping_ceiling=...)` flag, threaded from
heat_transmission for roof_construction_type containing "sloping ceiling"
(code 8) or "vaulted" (code 5). It fires only for the NI case
(thickness 0 + "insulated (assumed)"), routing to the col (1) age-band
default; the "ND"/None path is untouched (already col 1) and a NORMAL
pitched-with-loft roof still takes the §5.11.4 50 mm row (flag defaults
False). roof 76.93 → ~68 W/K → 0240 PE +5.5044 → +1.5181, CO2 +0.2757 →
+0.0728 (SAP integer 72 unchanged — the true value; lodged 73 needs the
unpreserved 2013+ pump).
Also corrects test_u_wall_cavity_as_built_partial_insulation_routes_to_
filled_cavity_row → ..._routes_to_as_built_row: a missed S0380.210
follow-up. That test (in domain/sap10_ml/tests/, which the AGENT_GUIDE §4
suite command does not run) asserted the pre-S0380.210 "partial insulation
→ filled" behavior on legacy-map parity, not worksheet evidence; S0380.210
corrected it to the as-built row per RdSAP 10 Table 6 + golden cert 0390's
four-metric closure.
Suite: 2614 passed, 1 skipped; the 2 remaining failures in
test_rdsap_uvalues.py (stone §5.6 thin-wall formula vs Table-6 1.7 cap)
are pre-existing (fail at HEAD 58ff7d88, before this branch's work).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The EPC renders a recent-band as-built wall as "<material>, as built,
insulated (assumed)". The API mapper populates epc.walls with that string,
and heat_transmission's wall_ins_present gate keyed off the "insulated"
substring → routed the wall to the RdSAP 50 mm "insulation of unknown
thickness" bucket (e.g. sandstone band J U=0.25) instead of the as-built
age-band row (U=0.35).
Per RdSAP 10 Table 8/9 footnote the 50 mm row applies ONLY when insulation
is "known to have been increased subsequently (otherwise 'as built'
applies)". An "as built ... (assumed)" description is the EPC's age-band
assumption — it only renders on RECENT bands (an old band renders "no
insulation (assumed)"), so the as-built row applies. Genuine retrofit is
signalled by wall_insulation_type (External/Internal/Filled), which the
gate still checks independently.
Worksheet-validated by two new Elmhurst worksheets, both As Built band J:
- simulated case 9: sandstone → (29a) U 0.35
- simulated case 10: solid brick → (29a) U 0.35
both the as-built row, NOT 50 mm (0.25).
Fix: restrict the description-based gate to genuine retrofit via the new
local `_described_as_retrofit_insulated` (excludes "as built"/"(assumed)").
The cavity filled-row routing inside `u_wall` (which uses
`_described_as_insulated` directly) is untouched — the 3 cavity API certs
(0390/0535/7536) are unaffected.
test_heat_transmission: the old `..._uses_50mm_row` test asserted 50 mm via
an IMPOSSIBLE band-B + "insulated (assumed)" combination; corrected to a
valid recent-band (J) scenario asserting the as-built row (35 W/K).
Golden 0240: walls 24.45 → 34.23 W/K (U 0.25 → 0.35). SAP integer 72
unchanged; PE residual re-pinned +1.8687 → +5.5044, CO2 +0.0907 → +0.2757.
This spec-correct fix REMOVED the wall under-count that was masking the
Ext1 vaulted-roof over-count (cascade U 0.68 via the same "insulated
(assumed)" description vs case-9 sloping-ceiling 0.25) — that roof
over-count is the next slice; fixing both lands SAP cont ≈ 72.31 (=
Elmhurst case 9).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
When two main heating systems heat different parts of a dwelling, SAP
10.2 §7 (PDF p.186) adapts the mean-internal-temperature calculation:
- Table 9b weighted responsiveness: R = (1−(203))·R_sys1 + (203)·R_sys2.
- Rest-of-dwelling temperature (90)m = weighted average of T2 computed
under EACH system's control schedule, weights (203)/[1−(91)] for sys2
and [1−(203)−(91)]/[1−(91)] for sys1 (or sys2's control alone when
(203) ≥ 1−(91)).
The cascade used Main 1's control + R=1.0 for the whole dwelling,
over-stating MIT by +0.037 °C on simulated case 6 (Main 1 radiators/2106
type 2 living + Main 2 underfloor/2110 type 3 elsewhere, R 1.0/0.75). That
inflated (97) heat loss by ~11 W → demand +61 kWh/yr.
`mean_internal_temperature_monthly` gains `main_2_control_type`,
`main_2_fraction`, `main_2_responsiveness`; cert_to_inputs derives them
from the second main detail (gated on main_heating_fraction > 0, so
single-main / DHW-only second mains pass the defaults → unchanged).
Case 6: (87) living, (90) elsewhere, (98c) demand 11991.96 and per-system
fuel (211)=7741.6458 / (213)=6995.3106 all match the worksheet to 1e-4.
Re-pin: golden 0240 (same 2106/2110 archetype, API-only) — PE +2.1519 →
+1.6893, CO2 +0.1051 → +0.0815 (both closer to zero; SAP 72 unchanged).
Single-main certs unchanged (2360 pass + 0 fail).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A rooflight deducts from the gross area of the roof element it pierces
(RdSAP 10 §3.7, PDF p.19). A "Roof of Room" rooflight (window_wall_type=4
/ site-notes "Roof of Room") sits on the room-in-roof sloped ceiling, so
its area must deduct from the §3.10.1 RR residual roof — not the flat /
loft external roof.
The cascade deducted every rooflight from the regular roof (heat_
transmission line 814). Simulated case 6's worksheet is the first
worksheet evidence for "Roof of Room" rooflight billing: "Roof room Main
remaining area" net 55.54 = gross 61.73 − 6.19 rooflights (U_RR=0.30),
while "External roof Main" 14.52 carries no opening. New
`_bp_rr_roof_absorbs_rooflight` routes the rooflight area to the RR roof
(simplified A_RR_final or detailed §3.10.1 residual) ONLY when the BP's
RR contributes such a shell AND lodges no explicit roof surface (slope /
flat_ceiling / stud_wall). Case 6 roof (30) 20.2284 → 19.0523 EXACT;
demand gap +153 → +61 kWh/yr.
Preserved: certs 000565 (Ext2 stud walls) and 000516 (slopes) lodge
explicit roof surfaces → rooflight keeps deducting from the regular roof
(their 1e-4 worksheet pins hold). Simplified Type 1 RR is excluded too.
Re-pin (uniform spec application per [[feedback-software-no-special-
handling]] + worksheet-is-truth): API certs 6035 and 0240 are detailed-RR
gables-only like case 6 (no worksheet of their own for rooflights), so
their "Roof of Room" rooflights now deduct from the RR residual too. This
SUPERSEDES the unvalidated S0380.198 "deduct from loft" assumption.
- 6035: roof 78.0648 → 73.9176; the previously-"unexplained" +1.37 PE
residual COLLAPSES to -0.14 (CO2 -0.0004 → -0.0362; SAP exact 70) —
strong corroboration the rooflight-on-RR treatment is correct.
- 0240: PE +2.5812 → +2.1519, CO2 +0.1269 → +0.1051 (SAP 72 unchanged).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The §5 (70) internal-gains mirror of S0380.201's Table 4f (230c). SAP
10.2 Table 5a note a) (PDF p.177) verbatim: "Where there are two main
heating systems serving different parts of the dwelling, assume each has
its own circulation pump and therefore include two figures from this
table. ... Where two main systems serve the same space a single pump is
assumed."
Simulated case 6 (dual oil, 51% radiators + 49% underfloor) lodges Main
1 "2013 or later" (3 W) + Main 2 unknown date (7 W) → worksheet (70) =
10 W in the 8 heating months. The cascade billed a single Main 1 pump
(3 W). New `_second_main_central_heating_pump_gain_w` adds the second
main's gain (at its own pump-age bucket), gated on a lodged
main_heating_fraction > 0 — the same genuine-second-space-heating-main
test as S0380.201, so DHW-only second mains (cert 000565 Main 2 combi via
WHC 914, fraction 0) keep a single pump (70)=3. Refactored the per-detail
pump predicate (`_main_detail_has_central_heating_pump`) and date bucket
(`_pump_date_category_for_detail`) out of the orchestrator.
Re-pin: golden 0240 (dual-main oil combi, both unknown date) (70) 7 → 14
W; the extra internal gain lowers space-heating demand → SAP cont 72.18 →
72.24 (integer 72 unchanged), PE +2.8092 → +2.5812, CO2 +0.1385 →
+0.1269 (both closer to zero). Validated against the case-6 worksheet.
This closes the (70) leg of case 6's space-demand gap. Remaining for full
case-6 closure: roof fabric (37) +1.176 W/K (room-in-roof shell) and HW
(216) Eq-D1 water efficiency −1.6%.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The cascade lumped a dwelling with two main heating systems into one:
`space_heating_fuel_monthly_kwh` hard-coded (203)=0 (a documented
scope-A placeholder) and the calculator's per-month fuel read only
main_1, so the full §8 space-heat demand billed against system 1's
efficiency. Simulated case 6 (one oil boiler feeding radiators 51% +
underfloor 49%) exposed it: main fuel ≈ demand/eff1 instead of the
worksheet's (211)+(213) per-system split.
Implements the SAP 10.2 §9a two-main model:
(204) = (202) × (1 − (203)) → system 1 share of total heat
(205) = (202) × (203) → system 2 share of total heat
(211)m = (98c)m × (204) × 100 / (206)
(213)m = (98c)m × (205) × 100 / (207)
(203) = the second system's lodged `main_heating_fraction`; (207) = its
own seasonal efficiency via the new per-detail `_main_heating_detail_
efficiency` (the core of `_main_heating_efficiency`, now reused for
system 2). Calculator `_solve_month` aggregates main_1 + main_2 into
`main_heating_fuel_kwh`. Cost (§10a 241), CO2 (§12 262) and PE (§13 276)
main_2 paths were already wired and now activate.
Site-notes gap also fixed: §14.1 Main Heating2 omits the "Fuel Type"
cell when the second system shares Main 1's fuel (case 6: one oil boiler,
two emitters). `_map_elmhurst_main_heating_2` now inherits Main 1's
resolved fuel as a fallback.
Blast radius: only dual-main certs. 0240 (2× oil code 130, identical
Eq-D1 efficiency) is unchanged — its split collapses to the lumped total.
Suite: 2355 passed, 1 skipped. New code: 0 pyright errors.
NOTE: case 6 is not yet fully pinnable end-to-end — its two systems have
DIFFERENT efficiencies (radiators 55°C → 79%, underfloor 35°C → 84%), a
flow-temperature boiler-efficiency adjustment not yet modelled, and its
dual-system auxiliary pumps ((230c)+(230d)=356) differ from the cascade.
Both are separate follow-on features; this slice is the §9a fuel split.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The calculator tests lived under domain/sap10_calculator/{tests,worksheet/
tests,rdsap/tests,climate/tests,validation/tests}, none of which are in
pytest.ini testpaths — so CI (which collects tests/) never ran them. Relocate
all five dirs to tests/domain/sap10_calculator/{,worksheet,rdsap,climate,
validation}, mirroring the tests/domain/property_baseline/ convention, so the
cascade-pin / golden / e2e conformance suites run in CI.
Mechanics:
- git mv preserves history (110 files).
- Flattening the trailing /tests keeps each file's depth-to-repo-root
identical, so all 16 repo-root parents[4] fixture refs stay valid. Only
test_pcdb_etl.py's parents[1] (→ pcdb data) and one hardcoded absolute
golden-fixture path in test_cert_to_inputs.py needed rebasing.
- Cross-imports rewritten domain.sap10_calculator.worksheet.tests →
tests.domain.sap10_calculator.worksheet (21 files incl. the external
importer backend/documents_parser/tests/test_summary_pdf_mapper_chain.py).
- Golden-fixture path strings in test_summary_pdf_mapper_chain.py +
scripts/fetch_cohort2_api_jsons.py updated to the new location (the JSONs
moved with the rdsap tests).
load_cells / gitignored worksheet xlsx: the xlsx-pinned tests (test_dimensions
/ ventilation / water_heating) read 2026-05-19-17-18 RdSap10Worksheet.xlsx,
which is gitignored (.gitignore `*.xlsx`) and so absent in CI. _xlsx_loader.
load_cells now pytest.skip()s when the file is absent, so those tests run
locally and skip cleanly in CI instead of erroring — no new CI failures from
the move, and the gitignore policy is respected.
Verified: tests/domain/sap10_calculator + backend/documents_parser +
tests/domain/property_baseline = 2248 pass, 1 skipped; pyright resolves the
new import paths with zero import-resolution errors.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
ADR-0014 BillDerivation prices a per-end-use EnergyBreakdown
(HEATING / HOT_WATER / LIGHTING / PUMPS_FANS / APPLIANCES / COOKING).
SapResult already carried the first four but not appliances or cooking,
so a downstream SapResult→EnergyBreakdown adapter had to stub those two
at 0 kWh — understating the bill by the whole unregulated electricity
load. Surface them so the property_baseline side can wire the sections.
Adds two output-only fields to CalculatorInputs + SapResult, threaded
exactly like lighting_kwh_per_yr:
appliances_kwh_per_yr — SAP 10.2 Appendix L L13/L14/L16a annual E_A
(sum of the §5 (68) monthly appliances kWh)
cooking_kwh_per_yr — SAP 10.2 Appendix L L20 (p.91) ELECTRICITY
estimate E_cook = 138 + 28×N
Both values already existed in cert_to_inputs.py (appliances_monthly_kwh,
cooking_monthly_kwh) — reused, not recomputed.
Fuel attribution: cooking_kwh_per_yr is the L20 ELECTRICITY figure (the
field docstring says so), distinct from the L18 cooking heat GAIN
(35 + 7N W) the §5 internal-gains cascade uses. The bill adapter should
treat cooking as an electricity carrier; a gas-cooker split, if ever
needed, is a separate follow-up.
HARD CONSTRAINT honoured — output-only, zero rating drift. Appliances +
cooking are unregulated and are NOT fed into ECF / total_fuel_cost /
CO2 / primary energy / sap_score. Every golden-fixture, Elmhurst e2e
SapResult pin, section cascade pin, and heating-corpus residual stays
byte-identical (1165 rated pins green). The synthetic CalculatorInputs
fixtures set the new fields non-zero on purpose so the existing cost/PE
reconciliation assertions act as leak detectors.
New focused test asserts both fields are populated (non-zero) and
threaded unchanged onto SapResult, with cooking equal to the L20
electricity figure (138 + 28×occupancy) to 1e-9. pyright net-zero
111 → 111.
Note: 11 pre-existing failures in test_appendix_u.py / test_table_32.py
arrived with the recently absorbed PR and are unrelated to this change
(they fail identically on the clean branch); flagged separately.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
SAP 10.2 Appendix N3.1 (PDF p.105) "Circulation pump and fan":
"For electric heat pumps: The electricity used by the water
circulation pump or fan is included within the calculated annual
space and hot water heating efficiency and is not included in
worksheet (230c). **The default heat gain from Table 5a is included
via worksheet (70).**"
This rule applies the Table 5a row "Central heating pump in heated
space" GAIN (3 / 10 / 7 W per pump-age bucket) to electric heat
pumps even though the pump ELECTRICITY is hidden in the COP and
excluded from (230c). The "Not applicable for electric heat pumps
from database" clause in Table 5a footnote a) scopes only to the
PCDB-Table-362 cascade case (Appendix N1.2.1: "For heat pumps held
in the PCDB ... a single water circulation pump serving the heat
emitters is sufficient" — pump kWh AND gain embedded in COP).
S0380.160 over-stripped the gain by zeroing pump_w for every HP
category-4 main, conflating the PCDB-Table-362 case with the Table-4a
default cascade. This slice refines the HP gate in
`_any_main_system_has_central_heating_pump`:
- Cat 4 HP WITH `main_heating_index_number` lodged (PCDB Table
362) → continue (skip; pump in COP per N1.2.1);
- Cat 4 HP with SAP code in `_TABLE_4A_WARM_AIR_SAP_CODES` (Cat 5
warm-air HPs distribute via ducted air, no water circulation
pump; warm-air fan handled separately by Table 5a "Warm air
heating system fans" row, S0380.161) → continue;
- Otherwise (Cat 4 HP, Table 4a default cascade, water-emitter)
→ apply Table 5a default per Appendix N3.1.
Per-line walk on ashp (SAP code 214 air-to-water HP, Cat 4, no PCDB,
"Post 2013" pump age):
worksheet (70)[Jan] = 3.0000 W
cascade pre-slice = 0.0000 W delta = -3.000 W
The -3 W winter gain shortfall over-stated cascade (84) Total gains
by -3 W in heating months → cascade SH demand +12.27 kWh/yr
(cascade 9302 vs worksheet 9290), pushing continuous SAP down 0.024
because the cost residual was driven by the +1.5 kWh × 12 month
shortfall flowing through the £0.0741 low-rate cost.
Closures:
ashp: ΔSAP -0.0240 → +0.0000 EXACT, Δcost +£0.55 → +£0.00 EXACT
gshp: ΔSAP -0.0178 → -0.0000 EXACT, Δcost +£0.41 → -£0.00 EXACT
ΔPE +36 → +25.51 (and ΔCO2 +7.33 → +6.31) — residuals narrow to the
Elmhurst-vs-spec HW PE annual-vs-monthly Table 12e/12d quirk only
(same pattern as the 16-variant lighting-PE deferred cohort,
scaled by HW kWh = 1138 vs 2384 → 25.51 vs 48.66). Cohort
Σ |ΔSAP_c| 0.07 → 0.03; all 25 cascade-OK variants now SAP+cost EXACT.
Cohort-1 (cert 0380 et al.) golden fixtures unaffected — those certs
lodge `main_heating_index_number` (PCDB Table 362) → HP gate skips
correctly → (70) = 0 preserved. Cert 000565 (HP main 1 + gas boiler
main 2) unaffected — wet-boiler branch fires for main 2.
Verbatim spec quote (SAP 10.2 Appendix N3.1, PDF p.105):
"For electric heat pumps: The electricity used by the water
circulation pump or fan is included within the calculated annual
space and hot water heating efficiency and is not included in
worksheet (230c). The default heat gain from Table 5a is
included via worksheet (70)."
Tests: 906 pass (+1), 0 fail. Pyright net-zero (35 → 35).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
SAP 10.2 Table 5a (PDF p.177) row "Warm air heating system fans
a) c)" computes the gain as SFP × 0.04 × V (W). Footnote c) sets
the default SFP to 1.5 W/(l/s) when no PCDB warm-air-unit record
is lodged; footnote a) applies the heating-season-only mask
(zero in summer months). Footnote c) further omits the gain when
the dwelling has balanced whole-house mechanical ventilation
(MVHR / MV) — same omission as the Table 4f kWh-side footnote e).
Pre-slice the cascade's `internal_gains_from_cert` only wired the
central-heating-pump row of Table 5a; the warm-air-fan gain helper
(`warm_air_heating_fan_w`) existed but was unwired. The kWh-side
parallel (Table 4f, 136.35 kWh/yr) was wired in S0380.158 — this
slice closes the symmetry on the gain side.
Per-line walk on electric 2 (SAP code 524 = Cat 5 ASHP with
warm-air distribution, V = 227.25 m³, no balanced MV):
worksheet (70)[Jan] = 13.6350 W
cascade (70)[Jan] = 0.0000 W delta = -13.635 W
worksheet (98c)[Jan] = 1600.43 kWh
cascade (98c)[Jan] = 1608.12 kWh delta = +7.69 kWh
13.635 W = 1.5 × 0.04 × 227.25 exactly. The -13.6 W winter gain
shortfall propagates through the §7 utilisation cascade and over-
states cascade SH demand by ~57 kWh/yr (cascade 9483 vs worksheet
9426), under-charging cost by ~£2.50 with opposite sign to the
S0380.156-.158 closures.
Fix: new `_any_main_system_has_warm_air_distribution(epc)` +
`_has_balanced_mechanical_ventilation(epc)` predicates in
`internal_gains.py`, mirroring `cert_to_inputs._TABLE_4A_WARM_AIR_SAP_CODES`
+ `_BALANCED_MV_KIND_NAMES` (kept here as siblings so the worksheet
layer stays free of rdsap deps). Orchestrator wires
`warm_air_heating_fan_w(sfp=1.5, dwelling_volume_m3)` into the
heating-season term of `pumps_fans_monthly_w` when warm-air
distribution is present and balanced MV is not.
Closures electric 2:
ΔSAP_c -0.1087 → -0.0000 EXACT
Δcost +£2.50 → -£0.00 EXACT
ΔCO2 +16.54 → +11.95 (joins lighting-PE deferred cohort)
ΔPE +97.69 → +48.66 (joins lighting-PE deferred cohort)
Electric 2 joins the 15-variant lighting-PE deferred cohort
(electric 1 + electric 3/5/6/7/8/9 + solid fuel 5/6/7/8 + solid
fuel 4/9/10/11 + electric 2) where SAP/cost are EXACT but PE/CO2
carry an Elmhurst-vs-spec MONTHLY-factor offset (cohort uses
Table 12 annual factors on the off-peak HW immersion line; spec
mandates Table 12d/12e monthly per the header).
Verbatim spec quote (SAP 10.2 Table 5a row "Warm air heating
system fans a) c)", PDF p.177):
"Warm air heating system fans a) c) SFP × 0.04 × V"
Footnote c): "SFP is the specific fan power from the database
record for the warm air unit if applicable; otherwise
1.5 W/(l/s). These values of SFP include an in-use factor.
If the heating system is a warm air unit and there is balanced
whole house mechanical ventilation, the gains for the warm air
system should not be included."
Footnote a): "... Set to zero in summer months. ..."
Σ |ΔSAP_c| across 25-variant cohort: 0.18 → 0.07 (~60% reduction).
No regressions on the other 24 variants or any golden fixture —
gate keyed on Table 4a warm-air SAP code frozenset (only electric
2 in the corpus has a code in that set).
Tests: 905 pass (+1), 0 fail. Pyright net-zero (35 → 35).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
SAP 10.2 Table 5a (PDF p.177) row "Central heating pump in heated
space" only applies to mains with a water-loop circulation pump.
Footnote a) names two exclusions verbatim ("Does not apply if a
heating system used solely for domestic hot water. ... Not applicable
for electric heat pumps from database."), and the row's name carries
the implicit third: dry mains with no central heating pump (electric
storage heaters, electric direct-acting, solid-fuel room heaters
without back-boilers) — the row simply doesn't list them.
Pre-slice `internal_gains_from_cert` gated only on Note a) (HP
exclusion), applying `central_heating_pump_w(date_category=...)` to
every non-HP main. The default UNKNOWN-date branch added 7 W of pump
gain to (70)m for every dry-system fixture in the controlled-variable
corpus, even though the worksheet (70)m = 0 every month.
Per-line walk on electric 3 (SAP code 401 "Manual charge control"):
cascade (73)[Jan] = 640.21 W
worksheet (73)[Jan] = 633.21 W delta = +7.00 W
cascade (70)[Jan] = 7.00 W
worksheet (70)[Jan] = 0.00 W Table 5a inapplicable
The +7 W winter-month gain lowered cascade SH demand by ~38 kWh/yr
(cascade 11050 vs worksheet 11088). At Table 32 18-hour low-rate
~7.4 p/kWh that's £2.50/yr under-charging — matching the cluster's
uniform Δcost = -£1.96..-£2.80 pattern. Continuous SAP rose ~+0.10
because cost dominates the ECF.
Fix: new `_any_main_system_has_central_heating_pump(epc)` predicate
in `internal_gains.py`, mirroring `cert_to_inputs._is_wet_boiler_main`
(S0380.149 — Table 4f kWh side). Wet if any non-HP main lodges:
- sap_main_heating_code in {101-141, 151-161, 191-196} (gas/oil/
solid-fuel/electric boilers per Table 4a/4b),
- main_heating_index_number (PCDB Table 322 record),
- main_heating_category in {1, 2} (RdSAP central heating), OR
- heat_emitter_type in {1, 3} (radiators / fan-coil per Table 4d).
Dead `_all_main_systems_are_heat_pumps` helper removed (the new
predicate subsumes its role).
Cluster closures (10 variants):
electric 3: SAP +0.1215 → -0.0000, cost -£2.80 → -£0.00
electric 5: SAP +0.1081 → -0.0000, cost -£2.49 → -£0.00
electric 6: SAP +0.1081 → -0.0000, cost -£2.49 → -£0.00
electric 7: SAP +0.1017 → -0.0000, cost -£2.34 → -£0.00
electric 8: SAP +0.0941 → -0.0000, cost -£2.17 → -£0.00
electric 9: SAP +0.1199 → -0.0000, cost -£2.76 → -£0.00
solid fuel 4: SAP +0.0850 → -0.0000, cost -£1.96 → -£0.00
solid fuel 9: SAP +0.1072 → -0.0000, cost -£2.47 → -£0.00
solid fuel 10: SAP +0.1134 → +0.0000, cost -£2.61 → -£0.00
solid fuel 11: SAP +0.0912 → +0.0000, cost -£2.10 → +£0.00
Σ |ΔSAP_c| across 25-variant cohort: 1.24 → 0.18. All 10 cluster
variants now join the lighting-PE +48.66 / CO2 +11.95 deferred
cohort (Elmhurst-vs-spec monthly factor quirk, same shape as
electric 1 + solid fuel 5/6/7/8 from prior closures).
Verbatim spec quote (SAP 10.2 Table 5a row 1, PDF p.177):
"Central heating pump in heated space, 2013 or later 3 a)"
"Central heating pump in heated space, 2012 or earlier 10 a)"
"Central heating pump in heated space, unknown date 7 a)"
The row name ("Central heating pump") gates by construction: dry
systems have no central heating pump and the row's three sub-rows
don't apply.
No regressions on the other 31 variants or any golden fixture; the
6 Elmhurst U985 fixtures lodge PCDB index → the new predicate
returns True → pump_w unchanged.
Tests: 904 pass (+1), 0 fail. Pyright net-zero (35 → 35).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
`test_ne_and_nw_share_table_u5_constants` asserts NE == NW, E == W,
SE == SW orientation-pairs share the same flux value per Appendix U
Table U5's column-sharing convention. The cascade looks up both via
the same dictionary key — the values are bit-identical, not
approximately equal. Tightened from `pytest.approx(..., abs=0.01)` to
exact `==` equality; abs=0.01 masked the fact that the cascade
returns the same float object.
Net pyright: unchanged.
Tests: 17 pass.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
17 hand-crafted ventilation tests had abs=0.001-0.01 tolerances that
masked the actual diff (always 0 or 1e-16 for these direct-arithmetic
formulas). Tightened to abs=1e-12 (essentially exact).
10 cohort cert pins (`LINE_8`/`LINE_10`/.../`LINE_25` against U985 PDF)
had mixed abs=0.0001-0.0005; standardised to abs=1e-4 (PDF 4-d.p.
display floor per [[feedback-e2e-validation-philosophy]]). The looser
0.0005 pins on (8), (16), (18), (21), (22b), (25) admitted up to half
a 4-d.p. unit of drift that the cascade isn't producing — actual
cascade diffs are ~5e-5 (one notch under display precision).
Test movement: all 26 tests pass at the new tolerances. Net pyright
change: 69 → 69.
Per [[feedback-zero-error-strict]] tolerance widening is forbidden;
this slice goes the other way — every pin tightened to its actual
precision floor.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
RdSAP 10 §5.11.4 (PDF p.44):
"If retrofit insulation present of unknown thickness use 50 mm."
The cascade encoded "unknown thickness" via the cert's "NI" (Not-
Indicated) sentinel which `_parse_thickness_mm` collapses to int(0).
But that conflates two structurally different signals:
(a) explicit int(0) — `_api_resolve_sloping_ceiling_thickness`
returns this for cert 001479 Ext2 PS sloping ceiling age C, a
per-BP "uninsulated" override of the dwelling-level description
("Pitched, insulated" from another BP).
(b) string "NI" — the cert lodgement marker for "thickness not
indicated; defer to description"; §5.11.4 should fire when the
description carries an "insulated" signal.
Pre-slice the heat_transmission cascade dropped `roof_description`
whenever `roof_thickness == 0`, killing the §5.11.4 path in `u_roof`
(line 711) for the (b) case. 346 corpus certs lodge the NI +
"insulated (assumed)" pattern per the §5.11.4 test's arrange comment.
Fix: inspect the raw `part.roof_insulation_thickness` value (pre-
parse) — drop the description only when the lodgement is the literal
int(0), keep it for the "NI" string sentinel so `u_roof`'s §5.11.4
branch fires (`_described_as_insulated` + thickness=0 → return 0.68).
Test movement:
test_roof_insulated_assumed_with_ni_thickness_uses_50mm_per_section_5_11_4 → PASS
test_summary_001479_full_chain_sap_matches_worksheet_pdf_exactly → PASS (cohort safe)
cert 000565 e2e — 11/11 PASS (unaffected — explicit per-BP thicknesses)
Golden corpus impact: cert 0240 had this exact pattern (BP[1] NI + global
description includes "Pitched, insulated (assumed)"). The fix drops its
roof U from 2.30 → 0.68 for that BP, closing massive mapper-gap residuals:
expected_sap_resid: -14 → -10 (Δ +4 SAP)
expected_pe_resid_kwh_per_m2: +12.49 → +0.054 (Δ −12.43 kWh/m²)
expected_co2_resid_tonnes_per_yr: +0.696 → +0.063 (Δ −0.633 t/yr)
Re-pinned per [[feedback-golden-residuals-near-zero]]: "Re-pin to the
new (smaller) value when a gap closes". The remaining 0240 residuals
(SAP -10 / PE +0.05 / CO2 +0.06) are tiny — the bulk of 0240's mapper
gap is now closed.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
The §5 test EPC builder threaded sap_windows from the fixture but
discarded `sap_roof_windows` — passing them through `make_minimal_sap10
_epc(...)`. Pre-S0380.110 the `_daylight_factor_from_cert` cascade
read a single aggregate `rooflight_total_area_m2` kwarg + bulk g_L,
so the test EPC builder's omission was masked. Post-S0380.110 the
cascade reads per-rooflight glazing via `epc.sap_roof_windows`
(Appendix L §L2a per-window g_L sum) — Triple / Double / Single
distinctions matter.
For cohort 000516 (the only cohort fixture with a lodged rooflight,
a Double-glazed 1.18 m² × g_L=0.80 × FF=0.70 × Z_L=1.0), the empty
sap_roof_windows on the test EPC undercut the daylight factor →
cascade lighting (67) Jan 33.78 W vs ws 32.68 W (+1.1 W/month) →
lighting_kwh_per_yr 238.65 vs ws 230.88 (+7.77 kWh/yr).
Fix: thread `fixture.build_epc().sap_roof_windows` through the
minimal EPC. Cohorts 000474/477/480/487/490 have no rooflights →
list is None → cascade unchanged for those certs.
Test movement: 000516 (67) Jan 33.78 → 32.68 ✓ EXACT. 000516
lighting_kwh_per_yr 238.65 → 230.88 ✓ EXACT.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Two changes bundled (same file, same RdSAP 10 §15 spec citation):
1. Tighten cohort cert (000474 / 000490) heat_transmission LINE_xx
pins from abs=0.01 / 0.1 → abs=1e-4 (4 pins). Pre-slice the cohort
landed at 1e-4 of the U985 PDF but the test pins were holdovers
from when the cascade was less precise. Per [[feedback-e2e-
validation-philosophy]]:
"per-component tests pin against U985 worksheet line refs at
<1e-3 tolerance ... 1e-4 since PDF lodges 4 d.p."
Probe data at HEAD post-§15:
000474 LINE_33 cascade=209.108439 ws=209.1084 Δ=+4e-5
000474 LINE_37 cascade=232.116939 ws=232.1169 Δ=+4e-5
000490 LINE_33 cascade=211.893610 ws=211.8936 Δ=+1e-5
000490 LINE_37 cascade=236.621110 ws=236.6211 Δ=+1e-5
2. Update `test_room_in_roof_simplified_type_1` and `..._type_2`
expected-value formulas to round A_RR_shell to 2 d.p. per RdSAP
10 §15 (p.66) — matching the cascade behaviour now enforced by
Slice S0380.116. The unrounded expected was 100.9156 / 71.857;
spec-correct rounded is 100.919 (39.5285 → 39.53) and 71.846
(32.2749 → 32.27). Same abs=1e-4 pin enforces both arithmetic
and rounding correctness.
New import: `_round_half_up` from heat_transmission (the same
helper the cascade uses for §15 rounding).
Net pyright change: 71 → 71. Net test change: 4 newly-tight pins,
2 newly-passing RR synthetic tests, 670 → 670 passing.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
RdSAP 10 Specification §15 "Rounding of data" (PDF p.66):
"For consistency of application, after expanding the RdSAP data into
SAP data using the rules in this Appendix, the data are rounded
before being passed to the SAP calculator. The rounding rules are:
U-values: 2 d.p.
All element areas (gross) including window areas and conservatory
wall area: 2 d.p."
The §3.9.1 / §3.10.1 shell formula A_RR_shell = 12.5 × √(A_RR_floor /
1.5) produces a gross element area for the room-in-roof. Pre-slice the
cascade kept the raw float (e.g. cert 000565 BP[0]: 12.5 × √30 =
68.46532...), then subtracted lodged wall surfaces to obtain the (30)
residual roof area. The worksheet rounds A_RR_shell to 2 d.p. (68.47)
BEFORE the subtraction — per §15 above.
Cert 000565 has three BPs that fire this path (Main, Ext1, Ext3 — all
have detailed wall surfaces with no `slope` / `flat_ceiling` /
`stud_wall` lodgement, so §3.10.1 residual fires). Each contributes a
sub-rounding residual that the unrounded cascade was missing:
BP[0] Main: 68.4653 → 68.47; residual 43.9653 → 43.97 (+0.0016 W/K)
BP[1] Ext1: 59.5119 → 59.51; residual 18.2519 → 18.25 (−0.0007 W/K)
BP[3] Ext3: 57.7350 → 57.74; residual 17.3450 → 17.35 (+0.0017 W/K)
Movement (HEAD `d0268a5b` → this slice) for cert 000565:
roof_w_per_k 51.3768 → 51.3795 ✓ EXACT (Δ −0.0027 → 0.0)
thermal_bridging 128.6448 → 128.6460 ✓ EXACT (Δ −0.0012 → 0.0)
total_external_a 857.6323 → 857.6400 ✓ EXACT (Δ −0.0077 → 0.0)
space_heating_kwh 59008.2363 → 59008.3499 ✓ EXACT (Δ −0.1136 → 0.0)
main_fuel_kwh 34710.7272 → 34710.7941 ✓ EXACT (Δ −0.0669 → 0.0)
total_fuel_cost 4680.2515 → 4680.2593 ✓ EXACT (Δ −0.0078 → 0.0)
co2_kg_per_yr 6447.6161 → 6447.6263 ✓ EXACT (Δ −0.0102 → 0.0)
sap_score_cont 28.5087 → 28.5087 ✓ EXACT (Δ +4.2e-5 → −4.7e-5)
sap_score (int) 29 ✓ EXACT (preserved)
ecf 5.38682 → 5.38683 (vs ws 5.3868, Δ +3.2e-5)
Cert 000565 truly closes — every SAP-result field within 1e-4 of the
worksheet PDF.
Cohort safety: 6 cohort certs (000474..000516) unchanged — cohort
000516's roof routes through the Detailed branch with `slope` /
`flat_ceiling` / `stud_wall` lodgements, so `has_roof_lodgement=True`
short-circuits the §3.10.1 residual block. Cohort certs 000474/477/
480/487/490 are pre-S0380.103 hand-built fixtures whose RR fields don't
exercise the simplified A_RR_shell path (rir.floor_area=0 or
detailed_surfaces only).
Test added: `test_summary_000565_a_rr_shell_rounded_2_dp_closes_roof_
w_per_k_per_rdsap_10_section_15` pins the cascade roof_w_per_k = 51.3795
exactly (Δ ≤ 1e-4 vs worksheet (30) Σ).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
The cert 000565 ECF pin was a transcription typo. U985-0001-000565.pdf
line 593 (Block 1, 11a SAP rating individual heating systems) reads:
Energy cost factor (ECF) [(255) x (256)] / [(4) + 45.0] = 5.3868 (257)
The pin captured 5.3866 — likely a mis-copy from line 871 / 873 (Nov
MIT (92)m = 15.3866). The cascade output 5.386823 matches the worksheet
PDF at 4 d.p.; the pin was always 0.0002 wrong against the source.
Per [[feedback-verify-handover-claims]], handover narratives are verified
against the source PDF; the cascade is correct and the pin was wrong.
Test movement: `test_sap_result_pin[000565-ecf]` now passes (diff
0.000023 against the corrected pin 5.3868, within abs=1e-4). Four
expected fails remain (cost / CO2 / SH / main_fuel) — closed in the
next slice (A_RR_shell rounding per RdSAP 10 §15).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
SAP 10.2 Table 5a (PDF p.177) verbatim:
"Central heating pump in heated space, 2013 or later: 3 W"
Note a): "Where there are two main heating systems serving
different parts of the dwelling, assume each has its own
circulation pump and therefore include two figures from this
table. ... Set to zero in summer months. **Not applicable for
electric heat pumps from database.** Where two main systems serve
the same space a single pump is assumed."
The Note a) "not applicable for electric heat pumps" rule zeros the
pump GAIN only for HP-category systems themselves. Where a cert
lodges a non-HP main system alongside an HP, the non-HP system's
circulation pump still operates and dissipates 3/7/10 W into the
dwelling as an internal gain.
Pre-slice the cascade conflated TWO different spec rules:
Table 4f (ELECTRICITY) — HP pump electricity is in the COP, so
worksheet line 230b = 0 for HP certs.
Table 5a (GAIN) — HP-from-database pump gain is omitted
ONLY for that HP system, not for any
non-HP system in the same cert.
`_main_heating_category_from_cert(epc)` returned `details[0].
main_heating_category` and the caller zeroed pump_w whenever that
was category 4. This dropped the 3 W gain for any cert whose first
main system was an HP — even when system 2 was a non-HP boiler with
its own pump.
Cert 000565 lodges TWO main systems:
[0] HP (category 4) pump_age "2013 or later"
[1] Gas boiler (category 2) pump_age None
Per spec the system [1] gas boiler's pump contributes 3 W (post-2013
date from [0]'s lodgement). Worksheet (70) confirms:
Pumps, fans 3.0 3.0 3.0 3.0 3.0 0.0 0.0 0.0 0.0 3.0 3.0 3.0 (70)
Pre-slice cascade returned 0 every month, missing 24 W·months of
winter internal gains. Downstream: +10 kWh space heating, +£0.71
fuel cost, +0.90 kg CO2, -0.008 continuous SAP.
Cert 0380 (cohort-1 ASHP, HP-only):
[0] HP (category 4) pump_age unknown
(no [1])
Worksheet (70) = 0 every month. Cascade post-slice: every main
system is HP → pump_w = 0 ✓ unchanged.
Fix:
`domain/sap10_calculator/worksheet/internal_gains.py`:
- Replace `_main_heating_category_from_cert` + the {4} set-membership
check with `_all_main_systems_are_heat_pumps(epc)`. Returns True
iff every lodged `main_heating_details[i].main_heating_category`
equals 4. Pump gain is zeroed only in that case.
- Existing `_pump_date_category_from_cert` (reads [0]'s pump_age)
unchanged — Elmhurst lodges the dwelling's pump_age on detail[0]
regardless of which system the pump serves.
Cohort safety: all 6 cohort certs have a single main system (gas
boiler, category 2) → `all_main_systems_are_heat_pumps` returns
False → pump_w applies, same as the prior `else` branch. Cert 0380
(ASHP) has a single HP main → True → pump_w = 0, unchanged.
Cert 000565 cascade snapshot (HEAD 59de805e → this):
(70)m pumps_fans gain [0]*12 → [3,3,3,3,3,0,0,0,0,3,3,3] ✓ EXACT
sap_score (int) 29 ✓ EXACT (preserved)
sap_score_continuous 28.5007 → 28.508742 (Δ -0.0080 → +0.000042)
**← essentially exact at 4.2e-5**
ecf 5.3876 → 5.386823 (Δ +0.0010 → +0.0002)
total_fuel_cost_gbp 4680.97 → 4680.2515 (Δ +0.71 → -0.008)
co2_kg_per_yr 6448.53 → 6447.6161 (Δ +0.90 → -0.010)
space_heating_kwh 59018.52 → 59008.2363 (Δ +10.17 → -0.114)
main_heating_fuel 34716.78 → 34710.7272 (Δ +5.98 → -0.067)
**Cert 000565 continuous SAP now exact at 1e-4 tolerance.** Every
intermediate (66-73, 83-84, 93-98, fuel/cost/CO2) closes the
worksheet at ≤1e-3 relative error.
Pyright net-zero (17 → 17 errors across touched files).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
RdSAP 10 §3.9.2 step (b) (PDF p.23) verbatim:
"Software calculates the area of each gable or adjacent wall by
using the equation:
A_RR_gable = L_gable × (0.25 + H_gable) − [(H_gable − H_common_1)² / 2
+ (H_gable − H_common_2)² / 2]"
Step (d):
A_RR_final = A_RR_wall − (Σ A_common + Σ A_gable + Σ A_party
+ Σ A_sheltered + Σ A_connected)
The spec equation is signed and applies for all L > 0 — including
H_gable = 0. When the gable is shorter than the common walls the
correction term `(H_gable − H_common)² / 2` exceeds the
L × (0.25 + H_gable) term, producing a negative A_RR_gable.
Elmhurst's worksheet evaluates the equation literally; the negative
value adjusts A_RR_final upward via step (d) without billing a
physical wall area.
Cert 000565 §8.1 lodges Ext3's RR (Simplified Type 2) with an
absent Gable Wall 2:
Gable Wall 1 L=9.00 H=7.00 Exposed U=0.45
Gable Wall 2 L=4.00 H=0.00 U=0.00 ← lodged but H=0
Common Wall 1 L=5.00 H=1.50 U=0.45
Common Wall 2 L=7.50 H=0.30 U=0.45
Spec equation for Gable Wall 2:
A_gable_2 = 4 × (0.25 + 0) − (0 − 1.5)²/2 − (0 − 0.30)²/2
= 1.0 − 1.125 − 0.045 = −0.17 m²
Worksheet (30) Ext3 residual = 17.35 m² back-solves exactly:
A_RR_shell = 12.5 × √(32.0 / 1.5) = 57.7350
Σ walls (incl. -0.17 absent gable) = 40.3850
residual = shell − walls = 17.3500 ✓ 4 d.p.
Pre-slice the mapper had two clamps that together dropped the
spec-computed −0.17 m² adjustment:
mapper.py:3350 `if length_m <= 0 or height_m <= 0: return None`
→ filtered out any H=0 surface
mapper.py:3443 `area_m2 = max(0.0, length_m * (0.25 + H) − correction)`
→ clamped negative gable areas at 0
Combined the cascade computed residual = 17.18 m² (cascade UNDER
by 0.17). Plus a related secondary `if height_m > h` filter on the
correction sum that masked the all-common-walls-taller case.
3-layer fix:
1. `datatypes/epc/domain/mapper.py` `_map_elmhurst_rir_surface`:
- Split the early-return filter: drop only when L<=0 (no wall),
OR when H<=0 AND not (Simplified Type 2 with common walls).
- Apply the spec gable-area formula to BOTH `gable_wall` (party
default) and `gable_wall_external` kinds in Simplified Type 2
(the U-value routing differs by kind, but the area equation
is the same).
- Remove `max(0.0, ...)` clamp so the signed result reaches the
cascade.
- Remove `if height_m > h` correction-sum filter (spec applies
the full square unconditionally).
2. `domain/sap10_calculator/worksheet/heat_transmission.py` per-
surface loop:
- `gable_wall` branch: skip `party += 0.25 × area` when area < 0
(wall doesn't exist physically) but still add the signed area
to `rr_walls_in_a_rr_area` so the residual deduction in step (d)
grows by |area|.
- `gable_wall_external` branch: same skip pattern for `walls +=
u × area` and `rr_detailed_area += area`.
Cohort safety: only cert 000565 Ext3 hits this in the corpus. All
other cohort certs are Type 1 RR (no common walls, formula gives
the same answer) or have all gables H > 0. The cascade's per-element
test pins (Ext1's Connected gable + Exposed gable, Ext4's Detailed
RR) unchanged.
Cert 000565 cascade snapshot (HEAD a461b70d → this):
roof_w_per_k 51.3185 → 51.3768 ✓ EXACT (Δ -0.06 → -0.003)
total_external_area 857.46 → 857.6323 ✓ EXACT (Δ -0.18 → -0.008)
thermal_bridging 128.62 → 128.6448 ✓ EXACT (Δ -0.03 → -0.005)
total_w_per_k 936.97 → 937.0563 ✓ EXACT (Δ -0.09 → -0.004)
sap_score (int) 29 ✓ EXACT (preserved)
sap_score_continuous 28.5027 → 28.5007 (Δ -0.0060 → -0.0080)
ecf 5.3877 → 5.3876
total_fuel_cost_gbp 4681.01 → 4680.97
co2_kg_per_yr 6448.59 → 6448.53
space_heating_kwh 59019.21 → 59018.52
main_heating_fuel 34715.31 → 34716.78
**Cert 000565 fabric cascade now essentially exact** (HTC −0.004 W/K
total residual across all 8 fabric components). The remaining
continuous SAP -0.0080 / cost +£0.71 / SH +10 kWh residuals come
from non-fabric upstream (likely ventilation or appliances) —
candidates for a future audit.
Pyright net-zero (57 → 57 errors across touched files).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
