The heat-pump PSR-extension fix (SAP 10.2 Appendix N2) drops corpus MAE from
0.740 to 0.726 on the 1000-cert RdSAP-21.0.1 sample; within-0.5 holds at
74.1%. Tighten the ceiling and log the slice.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
interpolate_heat_pump_efficiency_at_psr clamped to the smallest/largest PSR
row when the dwelling's plant size ratio fell outside the record's range.
That is the SAP 10.2 Appendix N rule for *combined heat-pump-and-boiler*
packages, not for a plain air/ground/water source heat pump.
Per Appendix N2 (PDF p.101, footnotes 44/45) a source heat pump whose PSR
exceeds the record's largest value takes a reciprocal-linear interpolation
between the largest-PSR efficiency and 100% at twice that PSR (100% beyond),
and 100% when the PSR is below the record's smallest value. Both the space-
and water-heating PSR-dependent efficiencies extend this way.
Effect: an oversized heat pump in a small dwelling is no longer credited the
full top-of-table COP. Accredited Elmhurst worksheet for cert 100110101713
(golden fixture case 56, PCDB 100061, PSR 3.107 over largest 2.0): (206)
334.4% -> 139.66% = Elmhurst exact. Corpus (RdSAP-21.0.1, n=1000) MAE
0.7397 -> 0.7258, within-0.5 0.7410 held; only two certs move (both
oversized-PSR heat pumps), 100110101713 +18.32 -> -4.97.
Exhaust-air and combined heat-pump-and-boiler packages have different
boundary rules (straight-to-100% / clamp-to-edge) but are not distinguished
by the current PCDB parse; the air/ground/water rule is applied uniformly,
a documented limitation noted in the function docstring.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
SAP 10.2 Appendix N2 (PDF p.101, footnote 44/45): for an air/ground/water
source heat pump whose plant size ratio exceeds the record's largest PSR,
the efficiency is reciprocal-interpolated between the largest-PSR value and
100% at twice the largest PSR (100% beyond that); below the smallest PSR the
efficiency is 100%. Our interpolator instead clamps to the top/bottom row.
Anchored to the accredited Elmhurst worksheet for cert 100110101713 (golden
fixture case 56, PCDB 100061): PSR 3.10665 over the record's largest 2.0
gives eta_space,1 = 147.011 -> (206) = 0.95 x 147.011 = 139.660, vs the
clamped 352.0 -> 334.4% that over-rates the dwelling by +18 SAP.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
0 = no PV, 1 = not connected to dwelling meter, 2 = connected. Decoded
empirically from the corpus + accredited Elmhurst (the gov RdSAP schema
types it as a bare int). Points readers to the crediting gate.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
within-0.5 floor 0.73->0.74 (now 0.741), MAE ceiling 0.762->0.740 (now
0.7397) on the fixed RdSAP-21.0.1 corpus. Log entry appended.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Gate PV generation/credit in cert_to_inputs on gov-API pv_connection:
credit only when ==2 ('connected'); ==1 ('present but not connected to the
dwelling's meter') contributes zero to the dwelling's cost/CO2/PE per
RdSAP 10 §11.1 / SAP 10.2 Appendix M. Non-int (None / site-notes str) keeps
the credit-if-array behaviour, so the Elmhurst/Summary + synthetic paths are
unchanged (no regression).
Corpus: all 5 pv_connection=1 PV certs move inside ±0.5 (e.g. 100051118081
+6.5→+0.5); MAE 0.760→0.740, within-0.5 73.8→74.3%, no regression
(pv_connection=2 certs keep their credit).
Also corrects a now-load-bearing latent bug: the solar-recommendation
overlay tagged recommended arrays pv_connection=1 ('not connected') — which
the new gate would zero. A new install connects to the dwelling's meter, so
it must be 2; pinned by the overlay test.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
RdSAP 10 §11.1 / SAP 10.2 Appendix M: PV is included in a dwelling's
assessment only if connected to the dwelling's own electricity meter. The
gov-API pv_connection enum encodes this — 0=no PV, 1=present-but-not-
connected, 2=connected. Corpus-validated (57 PV certs: pv_connection=1 MAE
4.48->1.22 without credit, 0/5 need it; pv_connection=2 needs it, MAE 0.98
vs 10.29) and Elmhurst-proven (connected SAP 87 vs not-connected 74).
cert_to_inputs currently credits a pv_connection=1 array; the test pins that
it must contribute zero generation. Adds pv_connection to make_minimal_sap10_epc.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Runs a Summary PDF through the chain-test path (pdftotext ->
ElmhurstSiteNotesExtractor -> from_elmhurst_site_notes) into Sap10Calculator
and dumps SAP + per-end-use kWh + the intermediate worksheet trail, for
diffing our calc against the accompanying Elmhurst U985 worksheet PDF.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
_is_elmhurst_roof_window routed a vertical window (Location "External wall")
to sap_roof_windows whenever its building part's roof type was a party
ceiling (A "Another dwelling above" / NR "Non-residential space above").
That is right for an EXTENSION (cert 000565 Ext2/Ext4 score on worksheet
(27a)) but wrong for the MAIN BP: a Main "A"/"NR" roof is the dwelling's own
party ceiling — no external roof — so its windows are vertical.
Gate the BP-roof-type rooflight rule to non-Main building parts. On a mid-
floor flat (case 53 / cert 000565 re-keyed) the Main External-wall window is
now vertical: its area deducts from the wall (was over-counted ~7 W/K) and it
prices as a window. Summary-path SAP 74.0 -> 75.17, matching Elmhurst's
accredited worksheet (75; space-heat 3408.6 vs 3408.58) — confirming the
calculator is correct; the gap was the misclassification.
000565's extension rooflights, the "Roof of Room" branch, and the U>3.0
room-in-roof backstop are unchanged. gov-API path unaffected (it routes roof
windows via window_wall_type==4).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
_is_elmhurst_roof_window mis-routes a vertical window (Location "External
wall") to sap_roof_windows when the building part's roof is a PARTY ceiling
(A "Another dwelling above" / NR "Non-residential space above"). A party
ceiling has no external roof, so it cannot host a rooflight.
Surfaced by simulated case 53 (cert 000565 re-keyed as a mid-floor electric-
storage flat, roof "A Another dwelling above"): its External-wall window
(U 2.00) routed to sap_roof_windows -> window area not deducted from the wall
(wall over-counted ~7 W/K) + priced as a roof window -> our SAP 74.0 vs
Elmhurst worksheet 75. Elmhurst lodges it Type "Window", Location "External
wall".
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
