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 flagged "priority" (per-main boiler interlock −5pp) was already
implemented (S0380.141 cylinder-thermostat path + S0380.177 room-
thermostat path); case 6 already produces (206)=79/(207)=84 exactly and
0240 is a combi with no cylinder. Records that S0380.201 closed the
secondary dual-system pump item and the remaining case-6 gaps (space
demand +1.28%, HW −1.6%) for full-SapResult promotion.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Simulated case 6 (P960-0001-001431, dual oil boiler 51% rads + 49%
underfloor) worksheet (231) = 356 = (230c) central-heating pump 156 +
(230d) oil boiler pump 200. (230c) decomposes per SAP 10.2 Table 4f
note c) (PDF p.175): "Where there are two main heating systems include
two figures from this table" — Main 1 41 kWh (pump age "2013 or later")
+ Main 2 115 kWh (pump age unknown). The cascade summed only Main 1's
circulation pump, giving (231) = 241.
cert_to_inputs now adds the second main's circulation pump, gated on a
lodged main_heating_fraction > 0 (a genuine second SPACE-heating main —
the same test §9a uses to split space-heating demand). This excludes
DHW-only second mains (cert 000565 Main 2 = gas combi via WHC 914,
fraction 0); without the gate 000565's worksheet pins regressed +115 kWh.
Re-pin: golden 0240 (dual-main oil combi, API-only, no worksheet) gains
its Main 2 pump too (pumps_fans 315 → 430). Spec-correct per
note c and validated by the case-6 worksheet; SAP cont 72.55 → 72.18
(integer 73 → 72, resid +0 → -1), PE +1.9459 → +2.8092, CO2 +0.1226 →
+0.1385. The lodged 73 carries Elmhurst's own residual; the worksheet-
backed case 6 is the spec authority for the archetype.
Note: the boiler-interlock −5pp per-main determination the prior
handover flagged as the priority is already implemented (S0380.141
cylinder-thermostat path + S0380.177 room-thermostat path) — case 6
already produces (206)=79 / (207)=84 exactly, and 0240 is a combi with
no cylinder so correctly unpenalised.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Captures the session's window/RR/dual-main work (S0380.196–200) and the
open priority: a spec-accurate per-system boiler-interlock −5pp (Table
4c(2)) adjustment. Root cause for case 6's remaining deltas (sys-1 eff 79
not 84 + HW 4824 vs 4902) is the "room thermostat present but no cylinder
thermostat → no interlock" path that the current {2101,2102} no-interlock
rule misses. 0240 shares the controls + cylinder_thermostat=N so it will
re-pin (apply spec uniformly). Secondary: dual-system Table 4f pumps.
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>
Retracts the premature "6035 = lodged divergence" claim (S0380.195 commit
msg + fixture docstring). The golden residual SAP -2 / PE +19.16 / CO2
+0.42t is REAL and exceeds the fallback bar. Section-level diff of 6035
(API) vs sim case 4 (site-notes, pins @1e-4) localised it to a
cross-mapper parity break: roof W/K 78.33 (site-notes) vs 130.73 (API),
a +52 over-count from the API RR scalar path + roof_construction=4. Next
agent starts there.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
RdSAP 10 §5 (PDF p.29) "Floor infiltration (suspended timber ground
floor only)", age band A-E, splits on whether a floor U-value is
supplied:
a) [U-value supplied] if floor U-value < 0.5 → "sealed", (12) = 0.1
b) [no U-value supplied] retro-fitted insulation → "sealed" 0.1;
otherwise "unsealed", (12) = 0.2
`_has_suspended_timber_floor_per_spec` fed the cascade's COMPUTED default
U into rule (a), so an as-built/uninsulated suspended-timber floor whose
default U happens to be < 0.5 was marked "sealed" (0.1) where Elmhurst
uses "unsealed" (0.2). That dropped (18) infiltration 0.85 → 0.75, (25)
effective ACH, HTC, and understated space heating ~450 kWh.
Fix: gate rule (a) on `floor_u_value_known` — a computed default U is not
a supplied value, so it falls through to (b). Verified against the
cert 001431 sim-case-2 worksheet: floor "As built", U=0.43 (matches the
worksheet's (28a) 0.4300 exactly), (12)=0.2 unsealed. Golden cert 6035
(also a suspended uninsulated floor) is unaffected — its U=0.63 ≥ 0.5
already routed to unsealed.
Promotes sim case 2 to the e2e harness as `001431_rr` (Main + Extension
+ Simplified room-in-roof — the 6035 archetype). All 11 Block-1 line
refs pin at abs=1e-4, locking BOTH this fix and S0380.192 (Simplified-RR
remaining area) end-to-end: SAP 69, cost 920.5046, CO2 4566.7090, space
15269.8593, main fuel 18178.4039. 2319 passed (+11), 0 failed; pyright
net-zero.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Point-in-time note for the next agent: what S0380.185-189 shipped (worksheet
PE/CO2 pins, the two D_PV electricity-vs-gain fixes, and the thermal-mass-
parameter Table 22 fix), the per-line diagnosis template, the two worksheet-
block / gains-vs-solar traps, and the ranked open slices (Summary-path fuel
derivation first, then pin the simulated 001431 case, then cert 6035).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The §7 mean-internal-temperature cascade hardcoded the thermal mass parameter
(TMP) to 250 kJ/m²K at all 5 call sites, ignoring construction. RdSAP 10
§5.16 Table 22 (PDF p.48) makes TMP construction-dependent:
100 kJ/m²K — timber frame, cob, park home (regardless of internal
insulation); OR masonry (stone/solid brick/cavity/system
built) WITH internal insulation.
250 kJ/m²K — masonry WITHOUT internal insulation.
A too-high TMP inflates the §7 time constant τ = Cm/(3.6·H) (e.g. 40 h vs
16 h), under-cuts the temperature reduction between heating periods, and
over-states mean internal temperature → over-states space heating.
`_thermal_mass_parameter_kj_per_m2_k(epc)` classifies the MAIN building's
wall via the RdSAP `wall_construction` codes (5/7/8 = timber/cob/park) and
`wall_insulation_type` codes (3/7 = internal); unknown/curtain fall back to
the masonry 250 (no regression on unlisted classes). 17-case parametrised
test covers every Table 22 branch.
Diagnosis (per-line walk vs the user-simulated 001431 worksheet, same
archetype as golden cert 6035): fabric (26-37), internal gains (73), climate
(96)m and HTC (39) all EXACT; the entire +8.78 PE / -1.76 SAP gap was §7 MIT
(92) +0.71 °C, traced to TMP 250 vs Table 22's 100 (solid brick WITH internal
insulation). Fix closes the simulated case to 1e-4 on PE and CO2.
Blast radius: only golden cert 6035 re-pins (solid brick + internal
insulation) — SAP resid -6 → -2, PE +46.42 → +19.16, CO2 +1.07 → +0.42. The
47 dr87 cohort, 6 U985 fixtures and 41-variant heating corpus are all
masonry-no-internal → TMP unchanged at 250, all still pass. 2290 pass
(+17 new), 0 fail; pyright net-zero.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A single durable doc so agents can pick up the calculator without reading
historical handovers: (1) the accuracy bar for the two input paths
(site-notes 1e-4 vs worksheet; API 1e-4 when a worksheet exists, ±0.5
register fallback otherwise; cross-mapper parity); (2) the per-line-walk
debugging loop incl. comparing site-notes vs API; (3) the tools &
pipeline (Summary PDF → extractor → from_elmhurst_site_notes →
cert_to_inputs → calculate_sap_from_inputs → SapResult, plus the API
from_api_response front-end, section helpers, and where the test vectors
live). Pointer added from SAP_CALCULATOR.md; HANDOVER_* flagged as
point-in-time notes.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
SAP 10.2 Appendix M1 §3a (p.93) defines PV-eligible demand as
D_PV,m = E_L,m + E_A,m + E_cook,m + E_ES,m + (231)·n_m/365 + E_space,m + E_water,m
where E_L,m is the lighting ELECTRICITY (Appendix L eq L10, = line (232)).
The cascade fed `internal_gains_result.lighting_monthly_w` — the L12 internal
heat GAIN G_L,m = E_L,m × 0.85 ("assuming 15%" of lighting energy does not
become internal heat) — into D_PV, understating it by 15% of lighting on
every PV cert. That depressed the monthly β onsite/export split and
under-credited PV primary energy uniformly across the year.
Same gain-vs-electricity class as the cooking fix S0380.73 (L18 gain vs L20
electricity). Fix: scale the (shape-identical) lighting gain profile to the
annual E_L `lighting_kwh_per_yr` (= (232)), mirroring the (219)m hot-water
scale-to-annual. Magnitude-only, so the shape-weighted lighting CO2/PE
effective factor (Σkwh×f/Σkwh, magnitude-invariant) is unchanged; appliances
need no scaling (G_A = E_A, no 0.85). Diagnosis was empirical first (calc
lighting D_PV 95.1 vs worksheet (232) 111.88, ratio exactly 0.85) then
confirmed against the spec text (L9d/L10/L12, M1 §3a).
Impact (calc − full-precision dr87 worksheet): ALL 47 worksheet certs now
match at <1e-4 on BOTH PE (max |Δ| 0.0000 kWh/m²) and CO2 (max |Δ| 0.0000 kg)
— the convergence target, met cohort-wide. Combined with S0380.187 this
closes the entire gas+PV + ASHP PV residual. Re-pinned 47 worksheet residuals
to 0.0000 and 31 drifted lodged residuals (PV certs). SAP integers unchanged;
chain SAP 1e-4 intact (164 pass). 2273 pass, 0 regressions; pyright net-zero.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The PV onsite/export β-split (SAP 10.2 Appendix M1 §3a, p.93) divides PV
generation by the monthly PV-eligible electricity demand D_PV,m. The cascade
included main and water electricity (when those fuels are electric) but had
no term for SECONDARY space heating. For the 10 cohort-2 gas-main +
electric-secondary + PV certs, the (215)m secondary electric fuel was dropped
from D_PV,m — understating demand in the heating months only, depressing the
monthly β, and under-crediting onsite PV primary energy.
Spec: Appendix M1 §3a counts E_space,m as the dwelling's TOTAL electric
space-heating demand; for a gas-main/electric-secondary dwelling that is the
secondary fuel. Diagnosis was decisive: E_PV (generation) matched the
worksheet exactly every month, the onsite (233a) split diverged ONLY in
heating months (Jun-Sep near-exact), and all 10 affected certs have PV while
all clean gas certs have none. Empirically adding (215)m to D_PV closed cert
3136 onsite 726.9 → 790.3 (worksheet 792.1).
Impact (calc − full-precision dr87 worksheet), the 10 certs:
PE +0.5..+1.5 → +0.02..+0.046 kWh/m²; CO2 −0.5..−1.1 → +0.002..+0.0095 kg.
The whole 47-cert cohort now matches at PE <0.05 / CO2 <0.025. SAP integers
unchanged; chain SAP 1e-4 pins intact (164 pass). The uniform ~0.03 PE remnant
on PV certs is the separate (233a)/(233b) summer-month D_PV discrepancy.
Re-pinned the 10 worksheet + 9 lodged golden residuals (improvements).
2273 pass, 0 regressions; pyright net-zero (file's 32 errors pre-existing).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
SAP 10.2 worksheet block 12b/13b (367)/(467) for a community heating
electric heat pump (Table 4a code 304 → Table 12 fuel 41 "heat from
electric heat pump"). The HP meters grid electricity, so per Table 12
note (s)/(t) + block 12b/13b footnote (a) its emission/PE factor is the
MONTHLY Table 12d/12e cascade (fuel 41 = standard-electricity profile),
weighted by the network heat profile, then × 1/heat-source-eff (1/COP):
(367)/(467) = [(307)+(310)] / COP × Σ((307+310)_m × factor_m)/Σ(...)
Per-line walk of CH3 (the displayed (367) 0.1535 / (467) 1.5717 are PDF
artifacts; the (373)/(473) totals reconcile only with):
CO2 factor = 0.15040 (monthly Table 12d wtd) vs cascade annual 0.136
PE factor = 1.55692 (monthly Table 12e wtd) vs cascade annual 1.501
Pre-slice the cascade routed code 304 through the non-electric branch
(`_co2_factor_kg_per_kwh(main) × 1/COP` = annual × scaling). New
`_is_heat_network_electric_main` (heat-network main whose fuel has a
Table 12d monthly set — i.e. fuel 41) routes all four factor helpers
(main + HW, CO2 + PE) through the monthly cascade × 1/COP. Non-electric
heat networks (gas 51 / oil 53 / coal 54) have no monthly set → annual
path unchanged (CH1, CH6 untouched).
Closure (CH3 was already SAP+cost EXACT):
CH3 (HP/Elec) CO2 −75.32→+0.0000 (= [(307+310)/3]×(0.1504−0.136)),
PE −249.32→−0.0000 (× (1.5569−1.501)) — FULLY EXACT
Corpus now 40/41 EXACT on all four metrics. Only CH6 remains: its
worksheet lodges a manual DLF=1.0 ("two adjoining dwellings") absent
from the Summary PDF (byte-identical to CH4 bar fuel type) — an
architectural limit, not a cascade gap. 2226 pass + 1 skip + 0 fail
(tolerances 1e-4 all metrics); pyright net-zero 43→43.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
SAP 10.2 §10b: hot water for a community-heating dwelling bills at the
heat-network rate, not the cert-lodged fuel. Elmhurst §15.0 lodges
`water_heating_fuel_type = "Mains gas"` (3.48 p/kWh) as a placeholder on
community certs; the worksheet (342) Water-heating cost = (310) × the
S0380.171 CHP heat-fraction blend — the SAME rate as space heating (340).
Per-line walk of the CH2 block 10b:
(340) space = 11837.83 × 0.037955 = 449.3047 (cascade EXACT)
(342) water = 3854.12 × 0.037955 = 146.2830 (cascade billed
3854.12 × 0.0348 = 134.12 → −£12.16, the whole residual)
(350) lighting + (351) standing → (355) 754.1502.
`_hot_water_fuel_cost_gbp_per_kwh`'s `inherit_main_for_community_heating`
path already routes HW cost through `_fuel_cost_gbp_per_kwh(main)` (the
CHP blend), but its gate `_is_community_heating_hw_from_main` excluded
code 302. S0380.182 wired the 302 CO2/PE credit via
`_heat_network_code_302_effective_factor`, which intercepts the HW
CO2/PE helpers ABOVE this predicate's branch — so extending the
predicate to include 302 now affects ONLY the cost path.
Closures:
CH2 (CHP/Gas) SAP +0.5277→−0.0000, cost −£12.16→−£0.00 — FULLY EXACT
CH4 (CHP/Oil) SAP +0.5277→−0.0000, cost −£12.16→−£0.00 — FULLY EXACT
CH6 (CHP/Coal) SAP −7.49→−8.02, cost +£172.68→+£184.84 — its HW now
also bills the blend, compounding the DLF=1.0 quirk
(cascade DLF=1.45); same separate CH6 DLF front.
Corpus now 39 variants EXACT on all four metrics (CH2/CH4 join). Open:
CH3 CO2/PE (code-304 community-HP COP), CH6 all-metric (DLF=1.0 manual
override the Summary doesn't carry). 2225 pass + 1 skip + 0 fail
(tolerances 1e-4 all metrics); pyright net-zero 32→32.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
SAP 10.2 worksheet block 12b (CO2) / 13b (PE) for community heating
"CHP and boilers" (SAP code 302). Per unit of network heat fuel
H = (307)+(310) the effective generation factor is:
chp×100/(362)×f_fuel − chp×(361)/(362)×f_disp + (1−chp)×100/(367)×f_fuel
(363)/(463) CHP fuel = chp_frac × 100/heat_eff × f_fuel
(364)/(464) less credit = −chp_frac × elec_eff/heat_eff × f_disp
(368)/(468) boiler fuel = (1−chp_frac) × 100/boiler_eff × f_fuel
f_fuel = Table 12 heat-network fuel factor (the CHP unit and the back-up
boilers burn the same community fuel — verified vs CH2 gas / CH4 oil /
CH6 coal worksheets (363)/(368)); f_disp = Table 12f (PDF p.196) credit
for the CHP-generated electricity. RdSAP 10 §C (p.58) defaults: heat eff
50% (362), electrical eff 25% (361), boiler eff 80% (367); CHP heat frac
0.35 per-cert via community_heating_chp_fraction.
New `_heat_network_code_302_effective_factor` + Table 12f flexible
constants (0.420 CO2 / 2.369 PE) + RdSAP §C efficiency constants, wired
into all four factor helpers (main + HW, CO2 + PE) ahead of the existing
single-fuel / 1-over-heat-source-eff path. The worksheet (368)/(468)
boiler emissions DISPLAY rounded/mis-aligned in the PDF, but the
(373)/(473)/(386)/(486) totals reconcile only with the boiler at the
full Table 12 factor — verified EXACT.
Two spec citations applied:
- Table 12f flexible-operation default for RdSAP community CHP is an
Elmhurst engine choice (Table 12f notes make "standard" the default);
mirrored per [[feedback-software-no-special-handling]] and documented
in SAP_CALCULATOR.md §8.3.
- Table 12 heat-network oil/biodiesel CO2 (codes 53/56) corrected
0.298 → 0.335 per Table 12 (p.189) "assumes 'gas oil'"; the code-302
oil cascade (CH4) was the first to exercise it. PE 1.180 was already
correct. No other variant uses these codes (no regression).
Closures (CO2 + PE only — the CHP credit does not touch cost/SAP):
CH2 (CHP/Gas) CO2 −1411.49→+0.0000, PE +1331.23→+0.0000 EXACT
CH4 (CHP/Oil) CO2 −4378.24→−0.0000, PE +319.81→−0.0000 EXACT
CH6 (CHP/Coal) CO2/PE re-pinned (+2411.54 / +5023.48) — its worksheet
lodges a manual DLF=1.0 the Summary doesn't carry, so
cascade DLF=1.45 over-scales H; same root as the CH6
SAP −7.49 / cost +£172 (separate DLF front).
CH2/CH4 are now CO2+PE-exact but still carry the heat-network cost/SAP
residual (+0.5277 SAP / −£12.16 cost, exposed by S0380.175 — cost-side,
untouched here). CH3 unchanged (code 304 community-HP COP front).
Corpus state: 37 variants EXACT on all four metrics (incl. CH1);
remaining residuals are CH2/CH4 cost+SAP, CH3 CO2+PE (HP COP), CH6
all-metric (DLF quirk). 2223 pass + 1 skip + 0 fail (tolerances 1e-4 all
metrics per S0380.181); pyright net-zero 43→43.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
SAP 10.2 Appendix C §C3.2 (PDF p.51), verbatim: "CO2 emissions and
Primary Energy associated with the electricity used for pumping water
through the distribution system are allowed for by adding electrical
energy equal to 1% of the energy required for space and water heating."
Worksheet line (313) = 0.01 × [(307)+(310)]; its CO2 (372) and PE (472)
bill on the Table 12d/12e monthly factors for fuel code 50 ("electricity
for pumping in distribution network"), weighted by the monthly heat
profile per worksheet footnote (a). (307)m/(310)m = (space_demand +
hw_output) / efficiency (the cascade models a heat network's generator
efficiency as 1/DLF).
This un-defers the (372)/(472) front the post-S0380.179 handover flagged
"don't guess until the factor source is identified": the source is
§C3.2 + Table 12d/12e code 50, NOT an empirical constant. The apparent
0.1994/0.2114 "factor" is an Elmhurst DISPLAY artifact — the worksheet
shows the (372) energy column as 0.01×(307) (space only) while computing
emissions on 0.01×(307+310) per the §C3.2 text. Verified EXACT line-by-
line against the CH2 corpus worksheet: (372)=23.6007 CO2 (rating),
(472)=208.2267 PE (demand).
New `_heat_network_distribution_electricity` helper (gated on
`_is_heat_network_main`) precomputes the energy + effective CO2/PE
factors; three new CalculatorInputs fields + calculator.py CO2/PE
summation terms (0.0/None → no-op for individually-heated certs).
Closures:
CH1 (Boilers/Gas) CO2 −23.60→−0.00, PE −208.23→+0.00 — FULLY EXACT
CH3 (HP/Elec) CO2 −98.92→−75.32, PE −457.54→−249.32 (distribution
component closed; code-304 community-HP COP remains)
CH2/CH4/CH6 gain their (372)/(472) component (CO2 +23.6, PE
+208.2); dominant CHP displaced-electricity credit
residual (Table 12f + block 12b/13b) is next slice.
No regression on the other 36 corpus variants (helper returns None off
heat-network mains) + golden + U985 fixtures. 2223 pass + 1 skip + 0
fail; pyright net-zero 43→43.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Captures the corpus state (36 EXACT + 5 pinned community-heating
variants), the SAP 302 CHP credit cluster as the highest-leverage
remaining front, the unresolved 0.8523 / 0.1994 worksheet-factor
mysteries to per-line-walk before hypothesising, and — importantly —
the new test layout (tests/domain/sap10_calculator/) that changes every
verification command.
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>
Two unrelated breakages surfaced after merging the PR into this branch;
neither was caused by the appliances/cooking work.
test_appendix_u.py (9 failures) — signature drift + wrong methodology
label. The climate lookups were renamed `external_temperature_c(region=…)`
→ `(region_or_climate, month)` when PostcodeClimate support landed for
the demand cascade, but the tests still passed `region=`. The expected
values match our SAP 10.2 _TABLE_U1/U2/U3 exactly (UK-avg Jan 4.3 °C,
Thames Jul 17.9 °C, solar Jul 189 W/m², Shetland Jan wind 9.5 m/s), so
these are valid 10.2 coverage — fixed the call signature to positional
and corrected the mislabelled "SAP 10.3" docstrings to SAP 10.2 (we
track 10.2 deliberately). Also converted pytest.approx → abs(x-y)<=tol
per the repo convention; pyright on the file drops 48 → 0.
test_table_32.py (2 failures) — the parametrised "match PDF p.95" test
pinned heating oil (code 4) = 7.64 and FAME (code 73) = 5.44, but the
table deliberately diverges from the PDF for these two carriers: oil =
5.44 (Slice S0380.131, two independent lodging engines agree the PDF
7.64 is the outlier) and FAME = 7.64 (Slice S0380.168). Updated the two
expected values to the worksheet-canonical figures the table actually
uses, with inline citations + a docstring note on the divergence.
Full calculator + property_baseline + heating-corpus suites: 1748 pass,
0 fail. pyright net-improving on both files.
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>
Closes the "no system" corpus variant fully (ΔSAP +1.18 → <1e-4 on all
four metrics).
The cert lodges §15.0 "Water Heating Code: NON / SapCode 999" and §15.1
"Hot Water Cylinder Present: No". Per RdSAP 10 §10.7 (PDF p.55) "No
water heating system" verbatim: "the calculation is done for an
electric immersion heater. If the electric meter is dual the immersion
heater is also dual, but is a single immersion otherwise... for a
cylinder defined by the first row of Table 28 (110 litres) and the
first row of Table 29." Table 29 row 1 gives age-band cylinder
insulation (age G -> 25 mm foam) and assumes a cylinder thermostat
present for immersion-heated DHW.
The BRE-approved Elmhurst engine confirms the substitution: the P960
worksheet header lodges "WHS: 903 Electric immersion, Single", a 110 L
cylinder, and storage loss (56) = 594.32 kWh/yr, so HW (64) = (45)
1935.37 + 594.32 = 2529.6927.
Pre-slice the cascade trusted the lodged "no cylinder" -> added no
storage loss and a spurious Table 3a keep-hot combi loss; the wrong HW
heat-gains also propagated through §5/§7, over-stating the base MIT by
+0.25 K and space fuel by +228 kWh. New
`_apply_rdsap_no_water_heating_system_default(epc)` rebinds the epc at
the top of cert_to_inputs (the demand cascade delegates here too) when
water_heating_code == 999, injecting WHC 903 + electricity fuel +
110 L cylinder + Table 29 insulation + assumed cylinder thermostat.
This closes HW fuel AND the downstream space residual in one move.
Age bands A-F (12 mm loose jacket) raise UnmappedSapCode — no corpus
member exercises that and the Table 2 loss-factor dispatch only has the
factory-foam path plumbed. Gate is keyed on code 999, unique to "no
system" in the corpus; 40 other variants + 858 section pins + 6 U985
fixtures unchanged. 936 pass; pyright net-zero 32 -> 32.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Closes the residual S0380.177 exposed on oil 6. The cascade's central
heating pump used the bare Table 4f age default (41 kWh for "2013 or
later") but the worksheet (230c) = 53.3 kWh.
SAP 10.2 Table 4f (PDF p.175) footnote a) on the "Circulation pump"
rows reads verbatim: "Multiply by a factor of 1.3 if room thermostat
is absent." oil 6 lodges control code 2101 ("No time or thermostatic
control of room temperature") = no room thermostat, so 41 x 1.3 = 53.3
= ws (230c) EXACTLY; pumps/fans (231) = 53.3 + 100 (liquid-fuel boiler
flue fan/pump) = 153.3 EXACT. Same root cause (absent room thermostat)
as the S0380.177 Table 4c(2) interlock fix — both keyed on the new
`_BOILER_NO_ROOM_THERMOSTAT_CONTROL_CODES = {2101, 2102}`.
`_table_4f_circulation_pump_kwh` now multiplies the resolved pump kWh
by `_TABLE_4F_NO_ROOM_THERMOSTAT_PUMP_MULTIPLIER = 1.3` when the main's
control code is in that set.
oil 6 now FULLY EXACT on all four metrics (ΔSAP/cost/CO2/PE < 1e-4).
The sibling oil 5 (same "2013 or later" pump age but control 2106 WITH
a room thermostat) keeps the bare 41 kWh and is unaffected — as do the
other 39 corpus variants (2101/2102 appear only on oil 6). 935 pass;
pyright net-zero 32 -> 32.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
oil 6 (B30K standard liquid-fuel boiler, Table 4b code 126 winter 80 /
summer 68) lodges Main Heating Controls Sap code 2101 ("No time or
thermostatic control of room temperature") WITH a cylinder thermostat.
The cascade's `no_interlock` gate only checked the cylinder thermostat,
so oil 6 kept raw efficiency despite the P960 worksheet header lodging
"Boiler Interlock: No".
Per RdSAP 10 §3 (PDF p.57): boiler interlock is "assumed present if
there is a room thermostat and (for stored hot water systems heated by
the boiler) a cylinder thermostat. Otherwise not interlocked." Control
code 2101 (and 2102 "Programmer, no room thermostat") provides no room
thermostat — the two Table 4e Group 1 rows carrying the "+0.6 °C /
Table 4c(2)" annotation — so the boiler is NOT interlocked regardless
of the cylinderstat. SAP 10.2 Table 4c(2) (PDF p.169) "No thermostatic
control of room temperature – regular boiler" then deducts 5pp from
BOTH the Space and DHW seasonal efficiency.
Three changes in cert_to_inputs.py:
- new `_BOILER_NO_ROOM_THERMOSTAT_CONTROL_CODES = {2101, 2102}`;
- `no_interlock` now ORs room-thermostat absence with the existing
stored-HW cylinderstat-absence test (the RdSAP §3 conjunction);
- the Space -5pp leg fires for Table 4b non-PCDB boilers (code
101-141), not only PCDB-record boilers; the DHW leg is gated on a
cylinder being present (Table 4c(2) combi DHW = 0).
Result for oil 6: space fuel (211) = 13446.3457 EXACT, HW fuel (219) =
4099.5872 EXACT. ΔSAP +3.0518 → +0.0782, Δcost -£69.79 → -£1.68,
ΔCO2 -240.66 → -1.71, ΔPE -1112.66 → -18.61.
The spec-correct fix exposes a single residual cause (per
[[feedback-software-no-special-handling]]): the central heating pump
(230c) — cascade reads pump_age=2 → Table 4f 41 kWh but ws (230c) =
53.3 kWh. The 12.3 kWh gap fully accounts for the residual across all
three metrics; pinned as the S0380.178 forcing function.
All other 40 corpus variants + 858 section pins + 6 U985 fixtures
unchanged (2101/2102 boiler codes appear only on oil 6). Pyright
net-zero.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
PR feedback: the SapResult -> Performance mapping should be a method, not a
free function you must know exists in the rebaseliner. Put the factory on
the target as `Performance.from_sap_result`, beside its sibling
`lodged_performance` and mirroring `Epc.from_sap_score` (the factory this
mapping already calls).
Not a `SapResult.to_performance()`: that would make the SAP calculator
import `Performance` (a property_baseline type), re-introducing the
engine->consumer coupling removed by the SapCalculator ABC. SapResult is a
TYPE_CHECKING-only import in performance.py (the body only reads attributes),
so the calculator module is not pulled in at runtime.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
PR feedback: annotate locals assigned from a method-call return or
attribute access, even though pyright infers them — the type is visible at
the assignment without chasing the callee. `result: SapResult` and
`sap_version: Optional[float]` in rebaseline(). Local annotations are not
evaluated at runtime, so the TYPE_CHECKING-only SapResult import stands.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
PR feedback: prefer an abstract base the calculator inherits from over a
structural Protocol. Define `SapCalculator(ABC)` in the calculator package
(the engine owns its own contract) and have `Sap10Calculator` inherit it;
a future methodology is another subclass. Placing the ABC with the engine —
not in property_baseline — keeps the dependency pointing consumer -> engine
(sap10_calculator imports nothing from property_baseline). Consistent with
the repo's existing port convention (FuelRatesRepository(ABC)).
CalculatorRebaseliner keeps its reference to SapCalculator type-only (under
TYPE_CHECKING), so the module still does not import the calculator at
runtime. Test fakes now inherit the ABC since structural conformance no
longer applies.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
SAP 10.2 §4 line 7702 (PDF p.137) defines (61)m as "Combi loss for
each month from Table 3a, 3b or 3c (enter '0' if not a combi
boiler)". Table 4b sub-rows 128 / 129 / 130 are explicit combi sub-
rows per the spec row names:
128: Combi oil boiler, pre-1998
129: Combi oil boiler, 1998 or later
130: Condensing combi oil boiler
Pre-slice `_table_3a_combi_loss_default_applies` gated only on
`main_heating_category ∈ {1, 2, 3, 6}`. The Elmhurst mapper leaves
`main_heating_category=None` on Table 4b liquid-fuel boilers (FAME,
HVO, B30K) — the cascade fell through to (61)m=0 despite the lodged
SAP code being a combi sub-row, under-counting (62)m by 600 kWh/yr
for FAME combi certs.
Extended the helper with a `_TABLE_4B_COMBI_OR_CPSU_CODES` fall-
through (set already exists for the symmetric `_primary_loss_
applies` Table 4b non-combi branch — see S0380.146). The set carries
the canonical combi + CPSU sub-row codes (103/104/107/108/112/113/
118/120-123/128-130). For cylinder-lodged certs the existing
`if epc.has_hot_water_cylinder: combi_loss_override = zero_monthly`
guard in `_water_heating_worksheet_and_gains` still pre-empts the
combi-loss fall-through correctly — non-combi codes with cylinders
remain (61)m=0.
Closures (heating-systems corpus 001431):
oil 3 (code 128, FAME, no cylinder) ALL EXACT (±0.0000):
ΔSAP_c +2.5863 → -0.0000
Δcost -£61.89 → -£0.00
ΔCO2 -14.58 → +0.00
ΔPE -967.10 → +0.00
oil 4 (code 129, FAME, no cylinder) ALL EXACT (±0.0000):
ΔSAP_c +2.5603 → +0.0000
Δcost -£56.66 → +£0.00
ΔCO2 -13.35 → +0.00
ΔPE -884.90 → +0.00
Oil 6 (code 126, NOT a combi, with cylinder) unchanged — the fix
is gated on the combi sub-row set. Cohort moves from 9 pinned
residuals to 7.
933 pass + 0 fail (+1 new mapper test). Pyright net-zero on cert_
to_inputs.py + tests.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
SAP 10.2 §4 "Heat networks" (PDF p.17 line 1482):
"Primary circuit loss for insulated pipework and cylinderstat
should be included (see Table 3)."
SAP 10.2 Table 2b note b (PDF p.159) verbatim:
"Multiply Temperature Factor by 0.9 if there is separate time
control of domestic hot water (boiler systems, warm air systems
and heat pump systems)."
The Table 2b note b ×0.9 multiplier is restricted to "boiler / warm
air / heat pump systems" — community heating is omitted from that
verbatim list. Pre-slice the cascade applied the ×0.9 reduction
unconditionally when DHW was separately timed, AND omitted the Table
3 primary-loss path for heat-network mains entirely. Combined the
two gaps under-counted (62)m HW total demand by ~320 kWh/yr for
heating-systems corpus 001431 community heating 1 (8164 + 0 vs
448.74 + 273.90 spec losses).
Three changes:
1. New `_HEAT_NETWORK_PIPEWORK_INSULATION_FRACTION = 1.0` constant.
`_primary_loss_override` selects this for heat-network mains
instead of the RdSAP §3 age-band default, per the spec's literal
"insulated pipework" + back-solve from worksheet (59) Jan = 23.26
= 31 × 14 × (0.0091×3 + 0.0263).
2. Extended `_primary_loss_applies` with a new branch: heat-network
main + WHC ∈ {901, 902, 914} + cylinder present → primary loss
applies.
3. New `_table_2b_note_b_multiplier_applies(epc, main)` predicate
that gates the ×0.9 storage-loss reduction on the spec's verbatim
system-type list, returning False for heat-network mains. The
primary-loss `_separately_timed_dhw` continues to return True for
community heating (Table 3's "separately timed" row is system-
type-agnostic and gives h=3 all year).
Closures (heating-systems corpus 001431):
CH1 HW kWh 3391.90 → 3854.12 (= ws 3854.1175, abs Δ < 1e-3)
CH1 HW cost £143.82 → £163.41 (= ws £163.41, EXACT)
CH1 (65)m heat gains 793.51 → 1221.62 (= ws 1221.62, EXACT)
CH2/CH3/CH4/CH6 same shape — HW path closes against ws (310).
§4 fix is spec-correct on all 5 CH variants. The closure surfaces a
separate §7 MIT (92)m over-count of +0.46 K (cascade Jan = 17.22 vs
ws 16.76) that the pre-slice (65)m gain under-count was masking. Per
[[feedback-software-no-special-handling]] apply the spec-correct
fix uniformly; new pinned residuals reflect the exposed MIT gap.
New residuals (vs pre-slice):
CH1 ΔSAP -0.5273 → -1.0572 ΔPE -9.15 → +408.67
CH2 ΔSAP -0.0076 → -0.4187 ΔPE +1506 → +1779
CH3 ΔSAP -0.5273 → -1.0572 ΔPE -387.03 → -239.03
CH4 ΔSAP -0.0076 → -0.4187 ΔPE +494.61 → +767.13
CH6 ΔSAP -8.0295 → -8.4406 ΔPE +7864.60 → +8137.11
927 pass + 0 fail (+1 new test). No regressions on the other 36
corpus variants — the gate is narrow on `_is_heat_network_main`.
Pyright net-zero (43 → 43) on cert_to_inputs.py + tests.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Closes CH1 (boilers) + CH3 (HP) HW CO2 / PE residuals by routing
the HW cost / CO2 / PE factor lookups through the heat-network main
when WHC ∈ {901, 902, 914} ("HW from main heating system"). Pre-
slice the cascade honoured Elmhurst Summary §15.0's
`water_heating_fuel_type = "Mains gas"` placeholder on community-
heated certs, mis-routing HW through Table 12 code 1 (mains gas,
3.48 p/kWh / 0.21 CO2 / 1.13 PE) instead of the heat-network code
(4.24 p/kWh + Table 12 code 41 / 51 / 53 / 54 with Table 4a heat-
source-eff scaling per S0380.172).
Per SAP 10.2 §C1 + RdSAP 10 §C (PDF p.49 + p.58) the HW heat
delivered by a heat-network main is supplied through the same
network as SH: spec block 10b (342a)/(342b) computes HW cost as
`(310a) × CHP_price + (310b) × boiler_price`, mirroring SH's
(340a)/(340b) split. Block 12b (365)/(366) and 13a (465)/(466)
likewise apply the heat-source-eff division on HW.
Three layers wired:
1. New `_is_community_heating_hw_from_main(epc)` predicate. Gates
on WHC ∈ {901, 902, 914} + heat-network main + SAP code in
`_HEAT_NETWORK_HEAT_SOURCE_EFFICIENCY` table (S0380.172 — only
301 boilers + 304 HP). SAP 302 (CHP+boilers) is excluded
because the 35%/65% split needs the displaced-electricity
credit cascade per spec block 13b (464)/(466) on BOTH SH and HW
paths — both converge in a single follow-up slice.
2. `_hot_water_fuel_cost_gbp_per_kwh` gains a keyword-only
`inherit_main_for_community_heating: bool = False` parameter.
When True, returns `_fuel_cost_gbp_per_kwh(main, prices)` —
same helper that already applies the S0380.171 CHP blend +
heat-network rate. The orchestrator passes
`inherit_main_for_community_heating=_is_community_heating_hw_
from_main(epc)` at the cost-rate construction site.
3. `_hot_water_co2_factor_kg_per_kwh` and `_hot_water_primary_
factor` get top-level branches: when the predicate fires, return
`Table_12_factor × _heat_network_heat_source_efficiency_scaling
(main)` — same scaled-factor return as the SH path in S0380.172.
Closures (heating-systems corpus block 11b):
CH1 (Boilers/Gas) ΔPE −967 → −9 (essentially closed)
CH1 ΔCO2 −126 → +52 (shifted across worksheet)
CH3 (HP/Elec) ΔPE +1749 → −387 (~78% closure)
CH3 ΔCO2 +473 → −86 (~82% closure)
Cost / SAP signs flip on CH1 / CH3 (was −£14 / +0.59 SAP, now
+£12 / −0.53 SAP) — HW cost now matches the worksheet's (342) line
exactly, exposing a +£12 lighting / standing overage that was
previously masked by the HW under-charge. Per [[feedback-software-
no-special-handling]] the pre-slice near-zero on CH1 / CH3 cost was
an offsetting-bugs artifact; the spec-correct fix surfaces the real
lighting / standing gap as the next forcing function.
CH2 / CH4 / CH6 (SAP 302) unchanged from S0380.171 / S0380.172 pins
— gated out per the heat-source-eff-table membership check.
Test baseline at HEAD: 926 pass + 1 skipped (was 926 + 1 at
predecessor 36d4bf87). Pyright net-zero on affected files
(cert_to_inputs.py, test_heating_systems_corpus.py): 32 → 32.
Per [[feedback-spec-citation-in-commits]] the rule cites SAP 10.2
§C1 verbatim ("heat from CHP + back-up boilers, via a heat main")
and RdSAP 10 §C defaults (PDF p.58).
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Closes the CO2 / PE residuals for CH1 (boiler community heating, SAP
code 301) and CH3 (HP community heating, SAP code 304) via SAP 10.2
Table 4a (PDF p.164) heat-network heat-source efficiency:
"Boilers (RdSAP)" → 80% → code 301
"Heat pump (RdSAP)" → 300% → code 304
Spec block 13a (PDF p.153) (467) "PE associated with heat source 2"
= [(307b)+(310b)] × 100 / (467b) — i.e. fuel input = network_input ×
100 / heat_source_eff before applying Table 12 PE factor. Block 12b
(367) mirrors for CO2. The cascade meters network_input directly
(eff = 1/DLF for the cost path via Table 12 heat-network rate), so
PE / CO2 factors are scaled by 1/heat_source_eff at lookup time —
mathematically equivalent to spec's (network_input / eff) × factor.
Three changes:
1. New `_HEAT_NETWORK_HEAT_SOURCE_EFFICIENCY: Final[dict[int, float]]`
keyed on SAP code: 301 → 0.80, 304 → 3.00. SAP 302 (CHP+boilers)
is omitted — the 35%/65% split + displaced-electricity credit per
spec block 13b (464)/(466)/(364)/(366) needs the .171 follow-up.
2. New `_heat_network_heat_source_efficiency_scaling(main)` helper
returning 1.0 for non-heat-network mains + SAP 302, and
1/heat_source_eff for SAP 301 / 304.
3. Wired into `_main_heating_co2_factor_kg_per_kwh` and
`_main_heating_primary_factor` non-electric branches (heat
networks are non-electric per `_is_electric_main`). Both functions
return `Table_12_factor × scaling` so the cascade's
`network_input × scaled_factor` lands on the spec
`(network_input / eff) × Table_12_factor`.
Closures vs pre-S0380.172 residuals (heating-systems corpus block 11b):
variant ΔCO2 ΔPE notes
CH1 (Boilers/Gas) -787→-126 -3827→-967 ~75-84% closure
CH2 (CHP/Gas) unchanged unchanged excluded — SAP 302
CH3 (HP/Elec) +1614→+473 +11879→+1749 ~71-85% closure
CH4 (CHP/Oil) unchanged unchanged excluded — SAP 302
CH6 (CHP/Coal) unchanged unchanged excluded — SAP 302
Cost + SAP unchanged on all 5 (heat-network rate × network_input via
Table 12 is correct regardless of heat-source efficiency).
Residual CH1 / CH3 gap drivers (follow-up scope):
- WHC=901 HW path: cascade reads cert-lodged "Mains gas" as HW fuel
on community-heating certs; should fall through to main fuel for
the heat-network so the scaling applies on HW side too.
- Elmhurst 0.8523 multiplier on heat-network energy column (worksheet
(467) energy = spec_formula × 0.8523 uniformly across non-CHP
heat-network rows; mechanism not yet identified — spec divergence
candidate for SAP_CALCULATOR.md §8).
Cohort no-regression verified: 9 ASHP + 38 cohort-2 golden fixtures
pass unchanged; the 41-variant heating-systems corpus has identical
residuals for non-heat-network certs. The 2 closed CH variants are
re-pinned at their new sub-1000 magnitudes.
Test baseline at HEAD: 926 pass + 1 skipped (was 926 + 1 at
predecessor a4b5f4e7; pin updates net to 0). Pyright net-zero on
affected files (cert_to_inputs.py, test_heating_systems_corpus.py):
32 → 32.
Per [[feedback-spec-citation-in-commits]] the dispatch table cites
SAP 10.2 Table 4a (PDF p.164) verbatim row labels.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Closes the +£104 cost / +4.5 SAP gap on CH2/CH4 (community heating
with CHP-fed mains-gas / oil boilers) by implementing the RdSAP 10
§C / SAP 10.2 Appendix C (PDF p.58) default heat-fraction split:
"If CHP (waste heat or geothermal treat as CHP):
- fraction of heat from CHP = 0.35
- CHP overall efficiency 75%
- heat to power ratio = 2.0
- boiler efficiency 80%"
Verified against the corpus block 9b lodgement: CH2 worksheet (303a)
= 0.3500 + (303b) = 0.6500 + (305) = 1.00 + (306) DLF = 1.45. The
worksheet block 10b cost cascade applies (340a) = (307a) × CHP_price
(Table 12 code 48 = 2.97 p/kWh) + (340b) = (307b) × boiler_price
(Table 12 codes 51-58 = 4.24 p/kWh) with (307a) = 0.35 × (307),
(307b) = 0.65 × (307).
Pre-slice the cascade dispatched single-fuel code 48 (CHP) for every
CHP variant and billed 100% of heat at 2.97 p/kWh, under-charging by
~£104/yr versus the worksheet's 35% × 2.97 + 65% × 4.24 = 3.7945
p/kWh blended rate.
Three layers wired:
1. Datatype — new fields on `MainHeatingDetail`:
- `community_heating_chp_fraction: Optional[float]`
- `community_heating_boiler_fuel_type: Optional[int]`
None on individually-heated dwellings + non-CHP heat networks
(Boilers-only + Heat-pump networks bill at a single Table 12 code
via main_fuel_type, unchanged path).
2. Mapper — new `_elmhurst_community_chp_split(community)` helper +
`_RDSAP_COMMUNITY_CHP_FRACTION_DEFAULT = 0.35` constant. When the
§14.1 Community Heat Source is "Combined Heat and Power": returns
(0.35, boiler_fuel_code) where boiler_fuel_code is resolved from
the §14.1 Community Fuel Type via the existing
`_ELMHURST_COMMUNITY_BOILER_FUEL_TO_TABLE_12` dispatch (gas → 51,
oil → 53, coal → 54).
3. Cascade — `_fuel_cost_gbp_per_kwh` now returns
`chp_frac × CHP_price + (1 - chp_frac) × boiler_price`
when both new fields are set on Main 1. Per [[feedback-spec-
citation-in-commits]] the implementation cites RdSAP 10 §C
verbatim. Non-CHP heat networks + individually-heated certs route
through the existing single-fuel-code branch unchanged.
5 new AAA tests parametrized over the 5 CH corpus variants in
`test_community_heating_mapper_populates_chp_split_fields` assert
the per-variant (chp_fraction, boiler_fuel_code) populates correctly.
Closures vs pre-S0380.171 residuals (heating-systems corpus block 11b):
variant ΔSAP Δcost status
CH1 (Boilers/Gas) +0.5915 -£13.63 unchanged (no CHP split)
CH2 (CHP/Gas) +4.50→-0.0076 -£104→+£0.17 ✓ CLOSED
CH3 (HP/Elec) +0.5915 -£13.63 unchanged (no CHP split)
CH4 (CHP/Oil) +4.50→-0.0076 -£104→+£0.17 ✓ CLOSED
CH6 (CHP/Coal) -3.52→-8.03 +£81→+£185 REGRESSED
The CH6 regression is exposed (not caused) by the spec-correct split:
pre-slice CH6 sat at -3.52 SAP / +£81 by coincidence — the cascade's
CHP-only pricing (2.97 p/kWh) cancelled with cascade DLF=1.45
(Table 12c age G default) against the CH6 worksheet's lodged DLF=1.0.
Per [[feedback-software-no-special-handling]] apply the spec-correct
fix uniformly; the pre-fix near-zero was an offsetting-bugs artifact,
not a deliberate non-spec rule.
The CH6 worksheet (306) DLF=1.0 is a cert-side quirk not currently
surfaced through the Summary PDF: CH4 and CH6 §14 lodgements are
IDENTICAL except for Community Fuel Type ("Mineral oil or biodiesel"
vs "Coal"), yet CH6's worksheet (306) = 1.0000 while CH4's = 1.4500.
The Elmhurst engine appears to override DLF for the coal-CHP combo
via a path not visible in the Summary; a follow-up slice will need to
either (a) add a §17 assessor-lodged DLF extractor or (b) extend the
mapper's age-band → DLF dispatch with a community-fuel-specific
override.
CO2 / PE residuals on all 5 CH variants are unchanged — this slice
touches cost only. The CO2 / PE cascade still needs: (1) the CHP
electricity-credit line (worksheet (464)/(466)/(364)/(366) per SAP
10.2 §13b spec — displaced-electricity reduction), (2) community-HP
COP cascade for CH3 (Table 12 code 41 PE/CO2 isn't divided by COP),
and (3) heat-network overall blended-factor (486)/(386) calc.
Test baseline at HEAD: 926 pass + 1 skipped (was 921 + 1 at
predecessor 9f0d23ad). Pyright net-zero on affected files
(epc_property_data.py, mapper.py, cert_to_inputs.py,
test_heating_systems_corpus.py + elmhurst_site_notes.py): 65 → 65.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Adds `"NON": 30` to `_ELMHURST_MAIN_HEATING_EES_TO_FUEL_CODE` so the
mapper can derive the main heating fuel for the Elmhurst "no main
heating system" lodging (§14.0 Main Heating EES = NON + SAP code
699 + §14.1 Heating Type = None).
SAP 10.2 §A.2.2: "When no main heating system is identified, the
calculation is for the assumed system consisting of portable electric
heaters." Routes the fuel to Table 32 standard-electricity code 30
(tariff resolved separately from `meter_type` per `_rdsap_tariff`).
Pre-slice the cascade raised `MissingMainFuelType` per S0380.132.
Post-slice the cascade closes most of the way:
no system: ΔSAP_c +1.18, Δcost −£27, ΔCO2 −50, ΔPE −562
The residuals are cascade-side (likely §A.2.2 portable-electric
efficiency / responsiveness / control-type defaults differ slightly
from Elmhurst) — pinned at observed values as forcing function for
follow-up.
Moves `no system` out of `_BLOCKED_BY_MISSING_MAIN_FUEL_TYPE` into
`_EXPECTATIONS`. Blocked tier now: 5 community-heating variants.
Tests:
- test_elmhurst_main_heating_ees_maps_no_system_code_to_electricity
- corpus pin: no system expected residuals at observed values
916 pass / 0 fail.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Mapper extensions (`_ELMHURST_MAIN_HEATING_EES_TO_FUEL_CODE`):
"BFD": 71, # HVO — corpus variant oil 2 (SAP 127)
"BXE": 73, # FAME — corpus variant oil 3 (SAP 128)
"BXF": 73, # FAME alt — corpus variant oil 4 (SAP 129)
"BZC": 76, # Bioethanol — corpus variant oil 5 (SAP 126)
"B3C": 75, # B30K — corpus variant oil 6 (SAP 126)
`_ELMHURST_MAIN_FUEL_TO_SAP10` water-side labels:
"Bio-liquid HVO from used cooking oil": 71,
"Bio-liquid FAME from animal/vegetable oils": 73,
"Bioethanol": 76,
"B30K": 75,
Values are direct Table 32 codes (the bio-liquid codes 71/73/75/76
don't collide with any API enum value so they pass through
`unit_price_p_per_kwh` etc. unchanged). Spec: SAP 10.2 Table 12
(PDF p.189) notes (d)/(e)/(f).
Pre-slice all 5 oil 2-6 variants raised `MissingMainFuelType` per
S0380.132. Post-mapper-extension cascade results:
oil 2 (HVO): SAP / cost / CO2 / PE all EXACT first try ✓
oil 5 (Bioethanol): SAP / cost / CO2 / PE all EXACT first try ✓
oil 3 (FAME): SAP +17.34, cost −£398
oil 4 (FAME alt): SAP +16.06, cost −£367
oil 6 (B30K): SAP +3.05, cost −£70
Slice S0380.131 had left a deferred TODO in `table_32.py` for FAME
code 73 ("worksheet 7.64 vs spec 5.44 — flipping has no measurable
cascade effect today, deferred until a cert that exercises it
surfaces"). Now exercised — flipping `73: 5.44 → 7.64` closes 85 %
of the oil 3/4 cost gap:
oil 3 (FAME): SAP +17.34 → +2.59, cost −£398 → −£62
oil 4 (FAME alt): SAP +16.06 → +2.56, cost −£367 → −£57
The Elmhurst-engine canonical 7.64 ↔ spec PDF 5.44 divergence is the
same pattern S0380.131 applied to heating oil (code 4: 7.64 → 5.44)
per [[feedback-software-no-special-handling]].
Remaining residuals on oil 3 / oil 4 / oil 6 are cascade-side
(HW kWh under by ~250-900, SH demand small diff, CO2/PE blend
artifacts) — pinned at observed values as forcing functions for
follow-up slices. Open fronts:
- HW kWh discrepancy on FAME (cascade applies different efficiency
path than Elmhurst for SAP codes 128/129)
- B30K (oil 6) Δcost −£70 with prices matching: SH/HW kWh gap
Closures `oil 2` / `oil 5`: ±0.0000 on all 4 metrics. Moves all 5
oil variants out of `_BLOCKED_BY_MISSING_MAIN_FUEL_TYPE` into
`_EXPECTATIONS`.
Blocked tier now: 6 variants (community heating × 5, no system).
Cascade-OK tier: 32 variants (up from 30), 30 EXACT + 3 (oil 3/4/6)
pinned with non-zero residuals + 1 (pcdb 1 SH residual closed in
S0380.165).
Tests:
- test_elmhurst_main_heating_ees_maps_bio_liquid_codes_to_table_32_fuel_codes
- test_elmhurst_main_fuel_to_sap10_maps_bio_liquid_water_heating_labels
- corpus pins: oil 2/3/4/5/6 expected residuals
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Slice 5a: the promotion. Replaces StubRebaseliner in production and collapses the
shadow runner into the rebaseliner (ADR-0013 amendment).
- CalculatorRebaseliner runs Sap10Calculator on every Property:
* sap_version < 10.2 -> Effective Performance IS the calculator output
(band via Epc.from_sap_score, CO2 kg->t, PEUI rounded), reason "pre_sap10".
* sap_version >= 10.2 -> Effective = lodged (API figures on-target), and the
calculator only logs divergence (SAP>0.5, PEUI/CO2 1%) as a validation signal.
* a calculator raise propagates -> batch aborts (ADR-0012); fix the cert at once.
- Rebaseliner.rebaseline gains property_id (for the divergence log).
- LoggingCalculatorShadow / the calculator_shadow seam removed from the
orchestrator; its divergence-comparison logic now lives in the rebaseliner.
- StubRebaseliner kept (signature updated) for orchestrator/repo unit tests.
The SapResult->EnergyBreakdown adapter + BillDerivation wiring (to populate the
bill block) follow once the appliances/cooking SapResult fields land.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Adds three Elmhurst EES (Energy Efficiency Standard) codes to
`_ELMHURST_MAIN_HEATING_EES_TO_FUEL_CODE` so the mapper can derive the
main heating fuel for electric storage / direct-acting certs whose
Elmhurst Summary §14.0 does not lodge a "Main Heating Fuel Type"
string (same pattern as the solid-fuel block above):
"WEA": 30, # electric warm-air storage
"REA": 30, # resistive electric (corpus electric 12 SAP 691)
"OEA": 30, # other electric (corpus electric 13/14 SAP 701)
All route to Table 32 standard-electricity code 30; the cascade
resolves the actual price tier (high vs low rate) downstream via
`_rdsap_tariff(epc)` keyed off `meter_type`.
The corpus carries 4 electric-storage variants on the 18-hour tariff:
electric 11 — WEA + SAP 515 (warm-air electric)
electric 12 — REA + SAP 691
electric 13 — OEA + SAP 701
electric 14 — OEA + SAP 701 (differs from 13 by emitter / controls)
Pre-slice all 4 raised `MissingMainFuelType` per S0380.132. Post-slice
all 4 EXACT on first try across all 4 metrics:
electric 11: ΔSAP_c +0.0000 Δcost +£0.0000 ΔCO2 −0.0000 ΔPE −0.0000
electric 12: ΔSAP_c +0.0000 Δcost +£0.0000 ΔCO2 −0.0000 ΔPE −0.0000
electric 13: ΔSAP_c +0.0000 Δcost −£0.0000 ΔCO2 +0.0000 ΔPE −0.0000
electric 14: ΔSAP_c +0.0000 Δcost −£0.0000 ΔCO2 +0.0000 ΔPE −0.0000
Closure on first try because the cascade was already wired for the
electric-storage path (SAP 10.2 Table 4a codes 515 / 691 / 701, Table
4e Group 4 storage controls, Table 5a pump-gain wet-gate from S0380.160,
S0380.144 secondary-fraction by sub-row); only the Elmhurst EES → fuel
mapping was missing.
Moves electric 11/12/13/14 out of `_BLOCKED_BY_MISSING_MAIN_FUEL_TYPE`
into `_EXPECTATIONS` at ±0.0000. Blocked tier now: 11 variants
(community heating × 5, no system, oil 2-6).
Tests:
- test_elmhurst_main_heating_ees_maps_electric_storage_codes_to_electricity
- corpus pins: electric 11/12/13/14 expected residuals = ±0.0000
Cascade-OK tier: 30 variants (up from 25), all SAP / cost / CO2 / PE
EXACT (< 1e-4) vs Elmhurst worksheet on every metric.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Slice 3 of Bill Derivation. sap_code_to_fuel(code) maps a SAP 10.2 / Table 32
fuel code to the canonical billing Fuel — bounded to the ~47 Table 32 codes (the
carrier, orthogonal to the PCDB product index, so all PCDB heat pumps share one
electricity code). Mains gas / LPG / oil+bioliquids / coal / smokeless / wood /
electricity (standard + off-peak) / heat-network groupings; an unmapped code
(dual fuel, grid-export) raises UnmappedSapCode rather than guessing.
Also: ADR-0014 deferred/TODO section records the stubbed appliances+cooking
(pending the SapResult fields), the off-peak day/night split, the heat-network
rate gap, and regional rates / ETL.
The SapResult -> EnergyBreakdown adapter (next slice) is gated on the
appliances/cooking fields landing on SapResult.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Adds the single missing dict entry that lets cert `pcdb 3` cascade:
`_ELMHURST_MAIN_FUEL_TO_SAP10["Bulk LPG"] = 27`
API code 27 = "LPG (not community)" — routes via:
- `API_FUEL_TO_TABLE_12[27] = 2` (SAP 10.2 Table 12 bulk LPG: £62
standing, 6.74 p/kWh, 0.241 CO2, 1.141 PE; spec PDF p.189)
- `API_FUEL_TO_TABLE_32[27] = 2` (RdSAP 10 Table 32 bulk LPG: £70
standing, 7.60 p/kWh; spec PDF p.95)
Pre-slice the mapper produced `main_fuel_type=''` for any Elmhurst
fixture lodging "Bulk LPG" as fuel type, so the cascade strict-raised
`MissingMainFuelType` per S0380.132. The legacy `"LPG bulk"` label
(different word order) maps to API code 6 = wood logs — a pre-existing
oddity unexercised by any live fixture; left untouched per
[[feedback-bigger-slices-for-uniform-work]] (different label, different
fix).
Cascade closure `pcdb 3` (Vokera Linea LPG combi 83.10 %, PCDB index
8262, no cylinder, 18-hour tariff) — EXACT on first try across all 4
metrics:
cascade SAP_c = 49.2953 worksheet = 49.2953 Δ = +0.0000
cascade cost = £1165.81 worksheet = £1165.81 Δ = +0.0000
cascade CO2 = 3367.95 worksheet = 3367.95 Δ = +0.0000
cascade PE = 13936.60 worksheet = 13936.60 Δ = +0.0000
Closure on first try because the cascade was already fully wired for
the gas/oil/LPG path; the Elmhurst label was the only gap. Moves
pcdb 3 out of `_BLOCKED_BY_MISSING_MAIN_FUEL_TYPE` into `_EXPECTATIONS`
at ±0.0000.
Blocked tier now: 15 variants (community heating × 5, electric storage
11-14, no system, oil 2-6).
Tests:
- test_elmhurst_main_fuel_to_sap10_maps_bulk_lpg_to_api_code_27
- corpus pin: pcdb 3 expected residuals = ±0.0000 on all 4 metrics
912 pass / 0 fail; pyright net-zero 43 → 43.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
SAP 10.2 §9.4.11 (PDF p.30): "The efficiency of gas and liquid fuel
boilers for both space and water heating is reduced by 5% if the
boiler is not interlocked for space and water heating."
S0380.141 had subtracted the -5pp from BOTH `Pwinter` and `Psummer`
PCDB / Table 4b seasonal efficiencies BEFORE running the SAP 10.2
Appendix D §D2.1 (2) Equation D1 monthly cascade. The Elmhurst P960
worksheet for `pcdb 1` (PCDB 716 oil boiler, Pwinter 65 / Psummer 53,
Cylinder Stat=No → no interlock) shows the -5pp is applied to the
η_water,monthly OUTPUT of Eq D1, NOT to its inputs. The two
interpretations diverge because Eq D1's reciprocal weighting (1/η_w
and 1/η_s) is non-linear in η.
Worked example for pcdb 1 Jan (Q_space=1409.77, Q_water=387.86):
Old cascade: Eq D1(60, 48, …) = 56.9292 % (off −0.04 pp)
Worksheet: Eq D1(65, 53, …) = 61.9725 %
−5pp = 56.9725 % ≡ (217)m_jan ✓
Across all 12 months the post-Eq-D1 form matches worksheet (217)m to
1e-4 every month. Cascade HW kWh: 7068.41 → 7063.96 (= worksheet (219)
total exactly), Δ −4.45 kWh.
The spec text "reduced by 5%" does not explicitly state pre- vs post-
Eq D1 ordering. Per [[feedback-software-no-special-handling]] mirror
the Elmhurst engine — the worksheet output is unambiguous.
Changes:
- `_apply_water_efficiency` gains a `interlock_penalty_pp: float = 0.0`
kwarg. Eq D1 branch runs on raw (Pwinter, Psummer), then subtracts
`interlock_penalty_pp / 100` from each monthly efficiency before
dividing.
- Caller (`cert_to_inputs` orchestrator) now passes the raw seasonal
efficiencies in `eq_d1_winter_summer_pct` + the penalty separately.
The pre-Eq-D1 `eq_d1_winter_summer_pct[0] -= 5` block is removed.
- SH-side `eff -= 0.05` (line 5349) is unchanged — the SH cascade
doesn't go through Eq D1, just `(98c)m / eff_sh`.
Closures `pcdb 1`:
ΔSAP_c −0.0108 → +0.0000 (1e-4)
Δcost +£0.24 → +£0.0000
ΔCO2 +1.33 → +0.0000
ΔPE +5.70 → −0.0000
No regressions on the other 25 cascade-OK variants — the gate is
`no_interlock AND eq_d1_winter_summer_pct is not None`, which fires
only when Cylinder Stat=No on a gas/oil boiler cert. The 6 Elmhurst
U985 cohort + cohort-2 Elmhurst fixtures all lodge Cylinder Stat=Yes
(interlock present) → no penalty fires; cohort-1 ASHP certs lodge no
cylinder thermostat at all but route through Appendix N3 instead of
Eq D1. 38 cohort-2 + 9 ASHP golden fixtures all PASS unchanged.
The 41-variant heating-systems corpus cascade-OK tier is now CLOSED:
all 25 variants SAP / cost / CO2 / PE EXACT vs Elmhurst worksheet at
abs < 1e-3 (most < 1e-4). Σ|ΔSAP_c| = 0.0001 (= floating-point noise).
Tests:
- test_apply_water_efficiency_applies_interlock_penalty_after_equation_d1
- test_apply_water_efficiency_interlock_penalty_zero_keeps_raw_eq_d1
911 pass / 0 fail; pyright net-zero 43 → 43.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Slice 2 of Bill Derivation. BillDerivation(fuel_rates).derive(breakdown) takes a
delivered-energy breakdown (per-section EnergyLine(section, fuel, kwh) +
exported_kwh) and produces a Bill: per-section kWh + cost, standing charges,
SEG credit, and total.
- Each end-use line billed at its fuel's unit rate.
- Standing charge added ONCE per distinct fuel used (a meter, not an end use);
off-gas fuels carry 0 so contribute nothing — no metered/unmetered special case.
- SEG export credit subtracted.
- Deterministic (ADR-0006); raises UnpricedFuel (via FuelRates) on an unpriced
fuel (e.g. heat network) rather than billing at a wrong default.
Pure domain — no calculator dependency; the SapResult->EnergyBreakdown adapter
is slice 3.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Slice 1 of Bill Derivation — the reference-data foundation that later slices
price the calculator's per-end-use kWh against:
- Fuel enum (canonical billing fuels; the join key between the calculator's
SAP-code fuels and the rates snapshot). COAL + HEAT_NETWORK are members with
no national rate.
- FuelRates value object: unit_rate_p_per_kwh / standing_charge_p_per_day /
seg_export_p_per_kwh; raises UnpricedFuel on a fuel it has no rate for rather
than billing at a wrong default.
- FuelRatesRepository port (ADR-0011 Repo-reads-stored-reference-data) +
StaticFileFuelRatesRepository reading a committed JSON snapshot.
- Snapshot fuel_rates_2026_q2.json: GB national, Apr-Jun 2026 Ofgem cap
(gas/electricity) + DESNZ/NEP May 2026 (off-gas). Carries the full researched
data; the value object exposes single-rate fuels this slice. Off-peak
(day/night), house coal and heat network raise UnpricedFuel until later slices.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
SAP 10.2 §12.4.4 (PDF p.36-37): "With open fire back boilers or closed
room heaters with boilers, an alternative system (electric immersion)
may be provided for heating water in summer. In that case water
heating is provided by the boiler for months October to May and by the
alternative system for months June to September."
The spec-literal CO2 / PE formula multiplies summer immersion fuel by
the Table 12d / 12e monthly cascade (per Table 12 footnotes (s) and
(t): "monthly factors in Table 12d/12e should be used in the SAP
worksheet"). The BRE-approved Elmhurst engine adds an extra
`summer_fuel × Table 12 annual electric` term ON TOP of the monthly
cascade for dual-rate tariffs — same Elmhurst-mirror shape as S0380.163
(§8.1) but additive rather than substitutive. Cost is computed
cleanly per spec — the double-count quirk only affects the (264) HW
CO2 and (278) HW PE factor lines.
Worksheet evidence (heating-systems corpus property 001431,
`solid fuel 2` — Table 4a code 158 closed-room-heater + back boiler,
65 % winter η + 100 % summer η, anthracite, 18-hour off-peak tariff):
(62)m heat 303.12 .. 168.95 .. 175.91 .. 300.40 kWh
winter fuel (W) = 2205.80 / 0.65 = 3393.51 kWh anthracite
summer fuel (S) = 684.55 / 1.00 = 684.55 kWh immersion
total fuel = (219) = 4078.06 kWh
(264) HW CO2 = 4078.06 × 0.3710 = 1513.15 kg/yr
= W × 0.395 + S × (0.116 monthly_summer + 0.136 annual)
= 1340.43 + 79.61 + 93.10 = 1513.14 ✓ within rounding
(278) HW PE = 4078.06 × 1.3771 = 5616.04 kWh/yr
= W × 1.064 + S × (1.429 monthly_summer + 1.501 annual)
= 3610.69 + 977.84 + 1027.51 = 5616.04 ✓ exact
The +annual term is precisely `S × Table 12 electric factor` and
matches the SF2 corpus pin's ΔCO2 = −93.10 and ΔPE = −1027.51 exactly.
Per [[feedback-software-no-special-handling]] mirror the engine.
Cascade rule (post-slice):
STANDARD tariff → winter × anth_annual + Σ wh_summer_m × Table 12d/e
(spec-literal, unchanged)
7h / 10h / 18h / 24h → winter × anth_annual + Σ wh_summer_m × Table 12d/e
+ S_fuel × Table 12 annual electric (Elmhurst mirror)
Closures `solid fuel 2`:
ΔCO2 −93.10 → +0.0000 EXACT
ΔPE −1027.51 → +0.0000 EXACT
ΔSAP and Δcost remain EXACT (cascade cost path was already correct).
The 41-variant heating-systems corpus is now closed on its 25-variant
cascade-OK tier: all 25 SAP / cost / CO2 / PE EXACT (|Δ| < 1e-3) vs
the Elmhurst worksheet. Only `pcdb 1` carries a sub-tolerance gap
(−0.011 SAP / +5.7 PE — PCDB Eq D1 cascade gap on PCDF index 716, a
separate small slice).
⚠ Single-cert evidence
SF2 is the only §12.4.4 fixture in the corpus (`solid fuel 1` =
code 156 is an empty folder; no other variant exercises a back-boiler
combo with summer immersion). Per the handover ≥2-cert rule for new
§8 divergence rows, this slice was admitted under an explicit
exception: the divergence shares its shape with §8.1 (S0380.163's
Table 12 annual mirror for dual-rate HW), and the math matches the
worksheet to within rounding. The new §8.2 row is tagged with a
"⚠ Single-cert evidence" subsection so future agents know to revisit
if a second §12.4.4 cert worksheet ever diverges from this rule.
Tests:
- test_section_12_4_4_hw_blend_mirrors_elmhurst_summer_annual_pe_co2_double_count
- test_section_12_4_4_hw_blend_standard_tariff_keeps_spec_literal_monthly_cascade
909 pass / 0 fail; pyright net-zero 43 → 43.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Wraps the four slices closing the heating-systems corpus from
Σ|ΔSAP_c| 1.24 → 0 (25/25 cascade-OK variants SAP/cost/CO2/PE
EXACT, except solid fuel 2 summer-immersion-blend artifact).
Highest-leverage next slice: close solid fuel 2 (the only remaining
open variant in the cascade-OK tier) via the S0380.154 blend code
path — likely a parallel Elmhurst-mirror gate for the summer-
immersion CO2/PE factors.
Other open fronts: 16 blocked-tier mapper extensions; pcdb 1 sub-
tolerance -0.011 SAP; cohort-2 golden residuals tightening per
[[feedback-golden-residuals-near-zero]].
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
