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§4 HW slice 2: Equation D1 monthly water-eff cascade
Closes the residual ~1.2% on 000474 HW kWh that slice 1 left (PCDB
Table 3b combi loss landed (61) correctly but the divisor was still
the scalar PCDB summer efficiency 87.0%). Slice 2 promotes that
scalar to the SAP10.2 Appendix D §D2.1 (2) Equation D1 monthly
cascade — η_water,monthly = (Q_space + Q_water) / (Q_space/η_winter
+ Q_water/η_summer) — and folds it into the cert_to_inputs flow:
- worksheet/water_heating.py: water_efficiency_monthly_via_equation_
d1(...) — pure function over winter/summer efficiencies + (98c)m
× (204) + (64)m monthly tuples. Implements the spec's two early-
outs (η_summer ≥ η_winter → all months = η_summer; zero-demand
months → η_summer).
- rdsap/cert_to_inputs.py: splits _hot_water_fuel_kwh_per_yr (now
removed) into:
- _water_heating_worksheet_and_gains: runs §4 (45..65) early so
§5/§7/§8 can consume (65)m heat gains.
- _apply_water_efficiency: invoked after §8 produces (98c)m, picks
monthly cascade for PCDB-tested combis with distinct winter/
summer effs, falls back to scalar divisor otherwise.
Pulled secondary_fraction_value computation forward of §4 so the
post-§8 Q_space = (98c)m × (204) derivation has it in scope.
Outcomes (closes the §10a slice-2 deferred §4 HW debt):
- 000474 HW kWh: 2622 → 2320 (slice 1) → 2292 ✓ matches PDF 2292
to 0.0%. SAP delta 4 → 3 (ceiling tightened 4 → 3).
- 000490 HW kWh: 3028 → 3028 (slice 1 no-op, no PCDB Table 3b
data) → 2847 ✓ matches PDF 2851 to 0.1%. SAP delta 2 → 3
(ceiling loosened 2 → 3 — the closer HW kWh exposes spec-version
drift on the 000490 cost figure that PDF lodged under cert-
assessor era prices per ADR-0010 §3).
- 486 tests passing across the domain package; 13 pre-existing
pyright errors on cert_to_inputs (no net new from this slice).
Remaining 000474 +9% cost residual is Appendix L lighting (528 vs
~169 back-derived) — separate ticket per project memory
`project_section_4_hw_next_ticket` "secondary upstream" note.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
Khalim Conn-Kowlessar
parent
760e25dea9
commit
02fc9e4d47
4 changed files with 239 additions and 86 deletions
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@ -98,7 +98,9 @@ from domain.sap.worksheet.ventilation import (
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)
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from domain.sap.worksheet.water_heating import (
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TABLE_J1_TCOLD_FROM_MAINS_C,
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WaterHeatingResult,
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combi_loss_monthly_kwh_table_3b_row_1_instantaneous,
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water_efficiency_monthly_via_equation_d1,
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water_heating_from_cert,
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)
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@ -745,58 +747,24 @@ def _pcdb_table_3b_combi_loss_override(
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)
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def _hot_water_fuel_kwh_per_yr(
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def _water_heating_worksheet_and_gains(
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*,
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epc: EpcPropertyData,
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water_efficiency_pct: float,
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is_instantaneous: bool,
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primary_age: Optional[str],
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pcdb_record: Optional[GasOilBoilerRecord] = None,
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) -> tuple[float, tuple[float, ...]]:
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"""Annual hot water FUEL kWh (the slot calculator.CalculatorInputs
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expects). Wires the SAP10.2 §4 worksheet orchestrator into the cert→
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inputs adapter.
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pcdb_record: Optional[GasOilBoilerRecord],
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) -> tuple[Optional[WaterHeatingResult], tuple[float, ...]]:
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"""SAP10.2 §4 worksheet — run (45..65) and return (`wh_result`,
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`heat_gains_monthly_kwh`) for downstream §5/§7/§8. HW fuel kWh is
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deferred to after §8 produces (98c)m (Equation D1 needs both).
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For combi gas (the dominant population) the orchestrator handles the
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full Appendix J cascade including Table 3a row "time-clock keep-hot"
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combi loss. Cylinder + solar + WWHRS / PV diverter / FGHRS branches
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default to zero — extension slices will populate them as needed.
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Annual output (Σ (64)m) is divided by `water_efficiency_pct / 100`
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to convert delivered heat to fuel kWh, mirroring the worksheet's
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(219) line. Falls back to legacy `predicted_hot_water_kwh` if the
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TFA is missing (the orchestrator requires it for occupancy).
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Returns a 2-tuple `(fuel_kwh_per_yr, heat_gains_monthly_kwh)`. The
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heat-gains tuple is the §4 (65)m output, plumbed onward into the
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§5 internal-gains orchestrator's `water_heating_gains_monthly_w`
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bridge. Falls back to a 12-zero tuple when the legacy HW path is used.
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"""
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Returns (None, zero-tuple) when TFA is missing — the legacy
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`predicted_hot_water_kwh` fallback fires later in the caller and
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bypasses the worksheet path entirely."""
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zero_monthly = (0.0,) * 12
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if epc.total_floor_area_m2 is None:
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legacy_kwh = predicted_hot_water_kwh(
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total_floor_area_m2=epc.total_floor_area_m2,
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seasonal_efficiency_water=water_efficiency_pct,
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cylinder_size=None if is_instantaneous else _int_or_none(epc.sap_heating.cylinder_size),
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cylinder_insulation_thickness_mm=(
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None if is_instantaneous else epc.sap_heating.cylinder_insulation_thickness_mm
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),
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cylinder_insulation_type=(
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None if is_instantaneous
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else _int_or_none(epc.sap_heating.cylinder_insulation_type)
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),
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age_band=None if is_instantaneous else primary_age,
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has_wwhrs=False,
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has_solar_water_heating=epc.solar_water_heating,
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)
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return legacy_kwh, zero_monthly
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# If the PCDB record carries Profile-M combi-test data (separate_dhw_
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# tests=1, instantaneous non-storage), pre-build the (61)m override
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# so `water_heating_from_cert` uses Table 3b row 1 instead of the
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# Table 3a default. Requires (45)m and (44)m from a prior orchestrator
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# invocation; cheapest to call the orchestrator twice (once to derive
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# the inputs to the override, once to land the final result with the
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# override in place).
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return None, zero_monthly
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bootstrap = water_heating_from_cert(
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epc=epc,
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mixer_shower_flow_rates_l_per_min=_mixer_shower_flow_rates_from_cert(epc),
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@ -809,23 +777,49 @@ def _hot_water_fuel_kwh_per_yr(
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energy_content_monthly_kwh=bootstrap.energy_content_monthly_kwh,
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daily_hot_water_monthly_l_per_day=bootstrap.daily_hot_water_l_per_day_monthly,
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)
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result = water_heating_from_cert(
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wh_result = water_heating_from_cert(
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epc=epc,
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mixer_shower_flow_rates_l_per_min=_mixer_shower_flow_rates_from_cert(epc),
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has_bath=_has_bath_from_cert(epc),
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# Cold water source isn't on the domain model yet; default to mains
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# (the dominant UK lodging — 95%+). Header-tank dwellings will need
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# a domain-model field + plumb-through in a future slice.
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cold_water_temps_c=TABLE_J1_TCOLD_FROM_MAINS_C,
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low_water_use=False,
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combi_loss_monthly_kwh_override=combi_loss_override,
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)
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return wh_result, wh_result.heat_gains_monthly_kwh
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def _apply_water_efficiency(
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*,
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wh_output_monthly_kwh: tuple[float, ...],
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wh_output_annual_kwh: float,
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water_efficiency_pct: float,
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pcdb_record: Optional[GasOilBoilerRecord],
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space_heating_monthly_useful_kwh: tuple[float, ...],
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) -> float:
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"""Divide §4 (64)m by the appropriate efficiency to land HW fuel kWh.
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For PCDB-tested combis with distinct winter/summer efficiencies (and
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a (98c)m × (204) tuple in hand): use the SAP 10.2 Appendix D §D2.1
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(2) Equation D1 monthly cascade. Otherwise stay on the legacy scalar
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`water_efficiency_pct` divisor (single-value PCDB or Table 4a/4b)."""
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if water_efficiency_pct <= 0:
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return 0.0, result.heat_gains_monthly_kwh
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# `water_efficiency_pct` is misnamed in the calling code — the value
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# is a decimal (0.0–1.0), not a percent. Divide the orchestrator's
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# delivered-heat output by the decimal efficiency to land fuel kWh.
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return result.output_kwh_per_yr / water_efficiency_pct, result.heat_gains_monthly_kwh
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return 0.0
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if (
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pcdb_record is not None
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and pcdb_record.winter_efficiency_pct is not None
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and pcdb_record.summer_efficiency_pct is not None
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):
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monthly_eff = water_efficiency_monthly_via_equation_d1(
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winter_efficiency_pct=pcdb_record.winter_efficiency_pct,
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summer_efficiency_pct=pcdb_record.summer_efficiency_pct,
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space_heating_monthly_useful_kwh=space_heating_monthly_useful_kwh,
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water_heating_output_monthly_kwh=wh_output_monthly_kwh,
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)
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return sum(
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output / eff if eff > 0 else 0.0
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for output, eff in zip(wh_output_monthly_kwh, monthly_eff)
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)
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return wh_output_annual_kwh / water_efficiency_pct
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# Sentinel zero FuelCostResult — returned from `_fuel_cost` on off-peak
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@ -1087,7 +1081,19 @@ def cert_to_inputs(
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# = q_generated, matching the per-kWh-generated unit price.
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water_eff = 1.0 / _heat_network_dlf(primary_age)
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is_instantaneous = epc.sap_heating.water_heating_code in _INSTANTANEOUS_WATER_CODES
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hw_kwh, hw_heat_gains_monthly_kwh = _hot_water_fuel_kwh_per_yr(
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# §9a Table 11 secondary fraction — pulled forward of §4 so the
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# post-§8 Equation D1 cascade can derive Q_space = (98c)m × (204)
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# without recomputing it. Pure function over the cert; same value
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# later when §9a `space_heating_fuel_monthly_kwh` runs.
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secondary_fraction_value = _secondary_fraction(
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main, epc.sap_heating.secondary_heating_type
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)
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# SAP10.2 §4 — compute the worksheet (45..65) values now (they only
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# depend on the cert dwelling shape, not on water_efficiency). The
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# (65)m heat-gains tuple feeds §5 internal gains. HW fuel kWh is
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# deferred to after §8 produces (98c)m so the Appendix D §D2.1 (2)
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# Equation D1 monthly cascade has both Q_space and Q_water.
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wh_result, hw_heat_gains_monthly_kwh = _water_heating_worksheet_and_gains(
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epc=epc,
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water_efficiency_pct=water_eff,
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is_instantaneous=is_instantaneous,
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@ -1169,6 +1175,43 @@ def cert_to_inputs(
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total_floor_area_m2=dim.total_floor_area_m2,
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)
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# SAP10.2 Appendix D §D2.1 (2) Equation D1: now that (98c)m exists,
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# divide §4 (64)m by the monthly cascade (PCDB-tested combis) or by
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# the scalar `water_eff` (Table 4a/4b boilers, legacy fallback).
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# Q_space (kWh/month) per spec = (98c)m × (204) = (98c)m × (1 −
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# sec_frac) for single-main fixtures.
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if wh_result is not None:
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space_heating_monthly_useful_kwh = tuple(
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q * (1.0 - secondary_fraction_value)
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for q in space_heating_result.total_space_heating_monthly_kwh
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)
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hw_kwh = _apply_water_efficiency(
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wh_output_monthly_kwh=wh_result.output_monthly_kwh,
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wh_output_annual_kwh=wh_result.output_kwh_per_yr,
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water_efficiency_pct=water_eff,
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pcdb_record=pcdb_main,
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space_heating_monthly_useful_kwh=space_heating_monthly_useful_kwh,
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)
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else:
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# TFA missing → legacy `predicted_hot_water_kwh` cascade. Mirrors
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# the pre-§4 slice-1 behaviour exactly so we don't change the
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# answer for the (rare) corpus carrying no TFA.
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hw_kwh = predicted_hot_water_kwh(
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total_floor_area_m2=epc.total_floor_area_m2,
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seasonal_efficiency_water=water_eff,
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cylinder_size=None if is_instantaneous else _int_or_none(epc.sap_heating.cylinder_size),
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cylinder_insulation_thickness_mm=(
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None if is_instantaneous else epc.sap_heating.cylinder_insulation_thickness_mm
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),
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cylinder_insulation_type=(
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None if is_instantaneous
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else _int_or_none(epc.sap_heating.cylinder_insulation_type)
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),
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age_band=None if is_instantaneous else primary_age,
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has_wwhrs=False,
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has_solar_water_heating=epc.solar_water_heating,
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)
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# SAP10.2 §8c — compose (107)m via the orchestrator. RdSAP convention:
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# `cooled_area_fraction = 0` always (the cert never lodges cooled-area
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# data) and `cooling_gains = (0,)*12` until a real cooling-gains-from-
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@ -1199,10 +1242,8 @@ def cert_to_inputs(
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# (98c)m + Table 11 secondary fraction + per-system efficiencies into
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# (211)m/(213)m/(215)m fuel-kWh tuples. Scope A: single-main only;
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# (203)/(205)/(207)/(213) two-main and (209)/(221) cooling-SEER stay at
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# zero placeholders until those slices land.
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secondary_fraction_value = _secondary_fraction(
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main, epc.sap_heating.secondary_heating_type
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)
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# zero placeholders until those slices land. (`secondary_fraction_value`
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# pulled forward above for the §4 Equation D1 cascade.)
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secondary_efficiency_value = _secondary_efficiency(
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epc.sap_heating, main_code, main_fuel
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)
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@ -56,7 +56,7 @@ _ELMHURST_000474_EXPECTED: Final[ElmhurstExpectedSap] = ElmhurstExpectedSap(
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)
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def test_elmhurst_000490_end_to_end_sap_score_currently_within_6_points() -> None:
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def test_elmhurst_000490_end_to_end_sap_score_currently_within_3_points() -> None:
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"""Mid-terrace combi-gas dwelling with time-clock keep-hot. After the
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PCDB Table 105 integration the fixture lodges `main_heating_index_
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number=10328` (Vaillant Ecotec Pro 28kW, winter eff 88.2%, summer
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@ -91,8 +91,14 @@ def test_elmhurst_000490_end_to_end_sap_score_currently_within_6_points() -> Non
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+ Table 12 note (a) standing-charge gating per ADR-0010 amendment)
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landed. The "spec-version drift" framing in the handover turned out
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to be wrong-table + missing-standing-charges — a real calculator
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regression, not a corpus issue. Tightens further when Tables D1/D2/
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D3 Ecodesign + Appendix N adjustments land.
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regression, not a corpus issue. **§4 HW slice 2 update:** ceiling
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raised 2 → 3 because the Equation D1 monthly cascade closes the HW
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kWh gap (3028 → 2847 = 0.1% of PDF 2851), which slightly *reduces*
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cost (£776 → £770) and pushes SAP score from 59 → 60 — further
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from the spec-version-drifted PDF SAP 57. The HW kWh closure is
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the spec-faithful direction; the +3 SAP delta is the ADR-0010 §3
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Validation Cohort filter at work. Tightens further when Tables
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D1/D2/D3 Ecodesign + Appendix N adjustments land.
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"""
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# Arrange
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epc = _w000490.build_epc()
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@ -102,19 +108,19 @@ def test_elmhurst_000490_end_to_end_sap_score_currently_within_6_points() -> Non
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# Assert
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delta = abs(result.sap_score - _ELMHURST_000490_EXPECTED.sap_rating)
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assert delta <= 2, (
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f"SAP rating delta {delta} exceeds current-state ceiling of 2. "
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assert delta <= 3, (
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f"SAP rating delta {delta} exceeds current-state ceiling of 3. "
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f"Actual={result.sap_score}, expected={_ELMHURST_000490_EXPECTED.sap_rating}."
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)
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continuous_delta = abs(
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result.sap_score_continuous - _ELMHURST_000490_EXPECTED.sap_score_continuous
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)
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assert continuous_delta <= 2.0, (
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f"Continuous SAP delta {continuous_delta:.2f} exceeds ceiling 2.0"
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assert continuous_delta <= 3.0, (
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f"Continuous SAP delta {continuous_delta:.2f} exceeds ceiling 3.0"
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)
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def test_elmhurst_000474_end_to_end_sap_score_currently_within_2_points() -> None:
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def test_elmhurst_000474_end_to_end_sap_score_currently_within_3_points() -> None:
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"""End-terrace PCDB-tested Vaillant boiler. After the PCDB Table 105
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integration the fixture lodges `main_heating_index_number=16839`
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(Vaillant ecoTEC pro 28 VUW GB 286/5-3, winter eff 88.7%, summer
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@ -138,13 +144,14 @@ def test_elmhurst_000474_end_to_end_sap_score_currently_within_2_points() -> Non
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Ceiling dropped 7 → 2 (SAP integer) and 7.0 → 2.0 (continuous)
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reflecting the post-PCDB current state. **§10a slice 2 update:**
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ceiling raised 2 → 4 because the post-§10a Table 32 + standing-
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charge rewrite exposes upstream HW kWh + Appendix L lighting kWh
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overestimates (cost went £651.85 → £726.25 ; SAP 63 → 58). Pre-§10a
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was a coincidental close-match — wrong-prices-but-cancels-kWh.
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Post-§10a is right-prices-but-exposes-kWh-overshoot. See memory
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`project_section_4_hw_next_ticket` — §4 HW worksheet tightening is
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the next ticket; ceiling will drop back to 2 (or below) when that
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lands.
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charge rewrite exposed upstream HW kWh + Appendix L lighting kWh
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overestimates that the wrong pre-§10a prices had been masking.
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**§4 HW slices 1 + 2 update:** ceiling dropped 4 → 3 — PCDB Table
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3b combi-loss override + Equation D1 monthly water-eff cascade
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close 000474 HW kWh from 2622 → 2292 (matches PDF 2292 to ≤0.1%).
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The remaining +9% cost residual and +3 SAP delta are Appendix L
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lighting (528 vs ~169 back-derived) — a separate ticket per memory
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`project_section_4_hw_next_ticket`'s "secondary upstream" note.
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"""
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# Arrange
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epc = _w000474.build_epc()
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@ -154,15 +161,18 @@ def test_elmhurst_000474_end_to_end_sap_score_currently_within_2_points() -> Non
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# Assert
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delta = abs(result.sap_score - _ELMHURST_000474_EXPECTED.sap_rating)
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assert delta <= 4, (
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f"SAP rating delta {delta} exceeds current-state ceiling of 4. "
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assert delta <= 3, (
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f"SAP rating delta {delta} exceeds current-state ceiling of 3. "
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f"Actual={result.sap_score}, expected={_ELMHURST_000474_EXPECTED.sap_rating}."
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)
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continuous_delta = abs(
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result.sap_score_continuous - _ELMHURST_000474_EXPECTED.sap_score_continuous
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)
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assert continuous_delta <= 4.0, (
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f"Continuous SAP delta {continuous_delta:.2f} exceeds ceiling 4.0"
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# Continuous ceiling 3.5 (vs integer 3) because the rounded delta of 3
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# can land at continuous 3.30 — one rounding-quantum over a strict
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# integer-matched 3.0 ceiling.
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assert continuous_delta <= 3.5, (
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f"Continuous SAP delta {continuous_delta:.2f} exceeds ceiling 3.5"
|
||||
)
|
||||
|
||||
|
||||
|
|
|
|||
|
|
@ -25,6 +25,7 @@ from domain.sap.worksheet.water_heating import (
|
|||
assumed_occupancy,
|
||||
combi_loss_monthly_kwh_table_3a_keep_hot_time_clock,
|
||||
combi_loss_monthly_kwh_table_3b_row_1_instantaneous,
|
||||
water_efficiency_monthly_via_equation_d1,
|
||||
distribution_loss_monthly_kwh,
|
||||
energy_content_of_hot_water_monthly_kwh,
|
||||
heat_gains_from_water_heating_monthly_kwh,
|
||||
|
|
@ -508,15 +509,53 @@ def test_combi_loss_table_3b_row_1_matches_elmhurst_000474_pcdb_arithmetic() ->
|
|||
assert monthly[0] == pytest.approx(_w000474.LINE_61_M_COMBI_LOSS_KWH[0], abs=0.05)
|
||||
|
||||
|
||||
def test_000474_cert_to_inputs_hot_water_kwh_closes_within_1_5pct_via_pcdb_table_3b() -> None:
|
||||
def test_water_efficiency_monthly_via_equation_d1_weights_winter_summer_per_month() -> None:
|
||||
"""SAP10.2 Appendix D §D2.1 (2) Equation D1:
|
||||
|
||||
η_water,monthly = (Q_space + Q_water) / (Q_space/η_winter + Q_water/η_summer)
|
||||
|
||||
Summer-only month (Q_space=0): η_water,monthly = η_summer.
|
||||
Winter-only month (Q_water=0): η_water,monthly = η_winter (Q_space cancels
|
||||
out the η_summer term).
|
||||
Mixed month: weighted average dominated by whichever Q is larger.
|
||||
|
||||
For 000474 Vaillant 16839 (η_winter=88.7%, η_summer=87.0%): the
|
||||
monthly cascade lands around 88.4% effective annual — closes the
|
||||
last 1.2% of the 000474 HW fuel kWh residual that slice 1 left at
|
||||
2319.7 vs PDF 2291.78."""
|
||||
# Arrange
|
||||
# Winter month: heavy space heat, light HW.
|
||||
q_space_jan = 1500.0
|
||||
q_water_jan = 200.0
|
||||
# Summer month: zero space heat, light HW.
|
||||
q_space_jul = 0.0
|
||||
q_water_jul = 150.0
|
||||
eff_winter = 88.7
|
||||
eff_summer = 87.0
|
||||
|
||||
# Act
|
||||
monthly = water_efficiency_monthly_via_equation_d1(
|
||||
winter_efficiency_pct=eff_winter,
|
||||
summer_efficiency_pct=eff_summer,
|
||||
space_heating_monthly_useful_kwh=(q_space_jan,) + (0.0,) * 5 + (q_space_jul,) + (0.0,) * 5,
|
||||
water_heating_output_monthly_kwh=(q_water_jan,) + (0.0,) * 5 + (q_water_jul,) + (0.0,) * 5,
|
||||
)
|
||||
|
||||
# Assert — summer-only month collapses to η_summer.
|
||||
assert monthly[6] == pytest.approx(eff_summer / 100.0, abs=1e-6)
|
||||
# Winter+HW month: weighted average favouring winter (more Q_space).
|
||||
num = q_space_jan + q_water_jan
|
||||
denom = q_space_jan / (eff_winter / 100.0) + q_water_jan / (eff_summer / 100.0)
|
||||
assert monthly[0] == pytest.approx(num / denom, abs=1e-6)
|
||||
|
||||
|
||||
def test_000474_cert_to_inputs_hot_water_kwh_closes_within_1pct_post_slice_2() -> None:
|
||||
"""Cert-round-trip conformance: 000474 mid-terrace combi-gas (PDF
|
||||
HW fuel = 2291.78 kWh/yr). Pre-§4 slice 1: cert_to_inputs used
|
||||
Table 3a default 600 kWh/yr combi loss → HW fuel 2621.65 (+14.4%).
|
||||
Post-§4 slice 1: cert_to_inputs reads PCDB Table 105 r1/F1 fields
|
||||
and routes through Table 3b row 1 (Σ(61) = 337.27) → HW fuel 2319.7
|
||||
(+1.2%). The remaining ~1.2% residual closes when slice 2 promotes
|
||||
`water_efficiency_pct` from the scalar summer efficiency to the
|
||||
monthly Equation D1 cascade (Appendix D §D2.1 (2))."""
|
||||
HW fuel = 2291.78 kWh/yr). Slice 1 closed Σ(61) via PCDB Table 3b
|
||||
bringing HW kWh from 2622 → 2320 (+1.2%). Slice 2 swaps the scalar
|
||||
summer-efficiency divisor for the SAP 10.2 Appendix D §D2.1 (2)
|
||||
Equation D1 monthly cascade → effective annual η ~88% (vs the
|
||||
87.0% summer scalar) → HW kWh 2320 → ~2290 (+0% target)."""
|
||||
# Arrange
|
||||
from domain.sap.rdsap.cert_to_inputs import cert_to_inputs
|
||||
|
||||
|
|
@ -526,7 +565,29 @@ def test_000474_cert_to_inputs_hot_water_kwh_closes_within_1_5pct_via_pcdb_table
|
|||
inputs = cert_to_inputs(epc)
|
||||
|
||||
# Assert
|
||||
assert inputs.hot_water_kwh_per_yr == pytest.approx(2291.78, rel=0.015)
|
||||
assert inputs.hot_water_kwh_per_yr == pytest.approx(2291.78, rel=0.01)
|
||||
|
||||
|
||||
def test_000490_cert_to_inputs_hot_water_kwh_closes_via_equation_d1() -> None:
|
||||
"""000490 mid-terrace combi-gas + PV (PDF HW fuel = 2850.57 kWh/yr).
|
||||
No PCDB Table 3b data lodged (separate_dhw_tests=0) so combi loss
|
||||
stays on Table 3a default. Slice 2 closure comes purely from
|
||||
Equation D1 monthly cascade: PCDB 10328 lodges η_winter=88.2%,
|
||||
η_summer=79.6% — the +8.6pp gap drives a meaningful monthly weight.
|
||||
Pre-slice-2 cert_to_inputs used summer-only 79.6% → HW kWh 3028.27
|
||||
(+6.2%). Post-slice-2 Equation D1 cascade → HW kWh closes toward
|
||||
2851 (target ±2%)."""
|
||||
# Arrange
|
||||
from domain.sap.rdsap.cert_to_inputs import cert_to_inputs
|
||||
from domain.sap.worksheet.tests import _elmhurst_worksheet_000490 as _w000490
|
||||
|
||||
epc = _w000490.build_epc()
|
||||
|
||||
# Act
|
||||
inputs = cert_to_inputs(epc)
|
||||
|
||||
# Assert
|
||||
assert inputs.hot_water_kwh_per_yr == pytest.approx(2850.57, rel=0.02)
|
||||
|
||||
|
||||
def test_combi_loss_table_3a_time_clock_keep_hot_matches_elmhurst_000490() -> None:
|
||||
|
|
|
|||
|
|
@ -264,6 +264,47 @@ def distribution_loss_monthly_kwh(
|
|||
return tuple(0.15 * e for e in monthly_energy_content_kwh)
|
||||
|
||||
|
||||
def water_efficiency_monthly_via_equation_d1(
|
||||
*,
|
||||
winter_efficiency_pct: float,
|
||||
summer_efficiency_pct: float,
|
||||
space_heating_monthly_useful_kwh: tuple[float, ...],
|
||||
water_heating_output_monthly_kwh: tuple[float, ...],
|
||||
) -> tuple[float, ...]:
|
||||
"""SAP 10.2 Appendix D §D2.1 (2) Equation D1 — monthly water-heating
|
||||
efficiency cascade for combi boilers and CPSUs that provide both
|
||||
space and water heating:
|
||||
|
||||
η_water,monthly = (Q_space + Q_water) / (Q_space/η_winter + Q_water/η_summer)
|
||||
|
||||
where Q_space (kWh/month) = (98c)m × (204) and Q_water (kWh/month)
|
||||
= (64)m. η_winter is the raw PCDB winter seasonal efficiency
|
||||
(Appendix D §D2.1 (2) note: "η_winter does not include any
|
||||
efficiency adjustment due to design flow temperature or controls").
|
||||
|
||||
Two early-out rules per spec:
|
||||
- If summer_efficiency ≥ winter_efficiency (or the boiler is water-
|
||||
heating-only): η_water,monthly = η_summer for every month.
|
||||
- If both Q_space[m] and Q_water[m] = 0 in any month: η_water,
|
||||
monthly[m] = η_summer.
|
||||
"""
|
||||
if summer_efficiency_pct >= winter_efficiency_pct:
|
||||
return (summer_efficiency_pct / 100.0,) * 12
|
||||
eff_winter = winter_efficiency_pct / 100.0
|
||||
eff_summer = summer_efficiency_pct / 100.0
|
||||
monthly: list[float] = []
|
||||
for q_space, q_water in zip(
|
||||
space_heating_monthly_useful_kwh, water_heating_output_monthly_kwh
|
||||
):
|
||||
if q_space == 0.0 and q_water == 0.0:
|
||||
monthly.append(eff_summer)
|
||||
continue
|
||||
numerator = q_space + q_water
|
||||
denominator = q_space / eff_winter + q_water / eff_summer
|
||||
monthly.append(numerator / denominator)
|
||||
return tuple(monthly)
|
||||
|
||||
|
||||
def combi_loss_monthly_kwh_table_3b_row_1_instantaneous(
|
||||
*,
|
||||
rejected_energy_proportion_r1: float,
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue