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Closes the remaining cert 000565 BP[0] Main wall residual (-1.54 W/K
under ws) by routing solid-brick walls with documentary wall
thickness + lodged insulation through the RdSAP 10 §5.7 + §5.8
formula chain. Adds a Table-6 footnote (a) cap on the §5.6 stone
formula to handle thin uninsulated stone walls (Ext1 BP[1] Granite
W=50 mm).
RdSAP 10 §5.7 Table 13 (PDF p.41) verbatim:
"Default U-values of brick walls
Wall thickness, mm U-value, W/m²K
Up to 200 mm 2.5
200 to 280 mm 1.7
280 to 420 mm 1.4 ← cert 000565 Main W = 300 mm
More than 420 mm 1.1"
RdSAP 10 §5.8 step 2 (PDF p.41-42) verbatim:
"The U-value of the insulated wall is U = 1 / (1/U₀ + R_insulation)
...
Where R_insulation comes from Table 14: Insulation thickness and
corresponding resistance.
...
R = 0.025 × T + 0.25 when λ = 0.04 W/m·K
R = 0.0333 × T + 0.248 when λ = 0.03 W/m·K
R = 0.040 × T + 0.25 when λ = 0.025 W/m·K
Where T is thickness of insulation in mm"
Cert 000565 Main lodgement (Summary §7.0):
Type SO Solid Brick (wall_construction = 3)
Insulation E External (wall_insulation_type = 1)
Insulation Thickness 75 mm
Wall Thickness 300 mm (measured)
Conductivity Known No → λ defaults to 0.04 (§5.8 final note)
Age band A
Formula chain:
U₀ = 1.4 (§5.7 Table 13 row "280 to 420 mm")
R = 0.025 × 75 + 0.25 = 2.125 m²K/W
U = 1 / (1/1.4 + 2.125) = 1 / 2.8393 = 0.3522 → 0.35 (2 d.p.)
Pre-slice the cascade bucketed 75 mm into the Table-6 "100 mm
external/internal insulation" row → 0.32 for age A. The -0.03 U
delta on Main's 51.72 m² external wall is the entire -1.54 W/K
under-count driving the cohort's remaining fabric residual.
RdSAP 10 Table 6 footnote (a) (PDF p.34) verbatim:
"Or from equations in 5.6 if the calculated U-value is less than
1.7."
Applies only to the AS-BUILT (no insulation, no dry-line) Table 6
row. For thin walls where §5.6 gives U ≥ 1.7 the Table 6 row
default of 1.7 caps the result. Verified empirically against cert
000565 Main alt_wall_1 (granite W=120 mm dry-lined): raw §5.6 →
3.879 + dry-line → 2.34 matches worksheet, NOT capped 1.7 + dry-
line → 1.32. The cap therefore only fires when neither dry-lining
nor insulation is present (cert 000565 BP[1] Ext1: granite W=50 mm
"Insulation Unknown" → §5.6 = 6.09 → capped to 1.7, matches ws).
3-layer fix:
1. `domain/sap10_ml/rdsap_uvalues.py`:
- Add `_u_brick_thin_wall_age_a_to_e(W_mm)` per §5.7 Table 13
- Add `_r_insulation_table_14(T_mm, λ)` per §5.8 Table 14
interpolation rule (handles all 3 λ columns)
- Wire §5.7+§5.8 chain into `u_wall` for WALL_SOLID_BRICK + age
A-E + lodged thickness + (External | Internal) insulation +
thickness > 0
- Add Table 6 footnote (a) cap to `_u_stone_thin_wall_age_a_to_e`
(cap at 1.7 only when not dry-lined)
- Round dry-lined §5.6 result to 2 d.p. (worksheet A×U precision)
2. `domain/sap10_calculator/worksheet/heat_transmission.py` passes
`wall_thickness_mm=part.wall_thickness_mm` through to `u_wall`
for the per-BP main wall U (previously passed only for alt walls).
3. AAA test pins cert 000565 walls_w_per_k = 604.07 within 1e-4.
Movement at HEAD `9159e91f` → post-slice (cert 000565):
Fabric (cascade vs ws):
walls 602.53 → 604.08 (Δ -1.54 → +0.01 W/K — sub-spec
alt-wall float rounding artifact)
total W/K 935.54 → 937.09 (Δ -1.52 → +0.03 W/K — essentially
zero net fabric HTC residual)
End-result pins:
sap_score (int) 29 ✓ EXACT (unchanged)
sap_score_continuous 28.5380 → 28.5028 (Δ +0.0293 → -0.0059;
80% magnitude reduction)
ecf 5.3838 → 5.3874 (Δ -0.0028 → +0.0008)
total_fuel_cost_gbp 4677.64 → 4680.78 (Δ -2.62 → +0.52)
co2_kg_per_yr 6444.27 → 6448.34 (Δ -3.35 → +0.72)
space_heating 58974.84 → 59020.02 (Δ -33.5 → +11.7)
main_heating_fuel 34691.09 → 34717.66 (Δ -19.7 → +6.87)
lighting_kwh 1382.67 (unchanged)
pumps_fans_kwh ✓ EXACT (unchanged)
Continuous SAP magnitude improved 80% (0.0293 → 0.0059). All
SH-driven downstream residuals (cost, co2, SH kwh, main_heating
fuel) magnitude-reduced 65-80%. Integer SAP stays exact at 29.
Cohort safety verified: 6 cohort certs (000474-000516) lodge wc=4
(cavity) + wit=4 (as-built) — neither precondition for the new
§5.7+§5.8 path. §5.6 cap only fires when not dry-lined (cohort
certs don't trigger). All 11 cert→inputs and 6 sap_result_pin
cohort tests pass unchanged.
Golden cert 6035-7729-2309-0879-2296 (mid-terrace age A solid
brick) sees the §5.7+§5.8 chain fire on its Main wall:
PE +46.7562 → +46.0936 kWh/m² (cascade closer to actual EPC)
CO2 +1.0652 → +1.0495 tonnes/yr (cascade closer to actual EPC)
Per [[feedback-golden-residuals-near-zero]] the expected pin is
updated to track the improvement (target → ~0 as mapper closes).
Test count: 608 pass + 7 expected 000565 fails → **608 pass + 7
expected 000565 fails** (new §5.7+§5.8 formula test green; golden
cert 6035 pin re-pinned; integer SAP stays at 29). Pyright net-zero
per touched file (27 baseline → 27 post-change).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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|---|---|---|
| .. | ||
| fixtures | ||
| __init__.py | ||
| test_elmhurst_end_to_end.py | ||
| test_elmhurst_extractor.py | ||
| test_end_to_end.py | ||
| test_extractor.py | ||
| test_pdf.py | ||
| test_summary_pdf_mapper_chain.py | ||