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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>
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| .. | ||
| handler | ||
| tests | ||
| __init__.py | ||
| db_writer.py | ||
| elmhurst_extractor.py | ||
| extractor.py | ||
| local_runner.py | ||
| parser.py | ||
| pdf.py | ||