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Slice 102e: heat-pump APM efficiencies via SAP 10.2 Appendix N3.6 / N3.7(a)
For any cert lodging a Table 362 heat-pump PCDB record, the cascade now replaces the Table 4a category defaults with PSR-interpolated efficiencies per SAP 10.2 Appendix N (PDF p.108): (206) = 0.95 × η_space,1_interp (N3.6 in-use factor) (217) = in_use_factor × η_water,3_interp (N3.7(a) + footnote 49) where η_space,1 and η_water,3 are PSR-dependent values from the PCDB record's PSR-group table (decoded in slice 102c.2), and the dwelling's PSR is computed per PDF p.100 line 5946-5950: PSR = max_nominal_output_kw / (HLC_annual_avg_W_per_K × 24.2 K / 1000) The N3.7 in-use factor (PDF p.6097) tests three cylinder criteria: 1. cert volume ≥ PCDB volume 2. cert heat-exchanger area ≥ PCDB area (unless PCDB area = 0 per fn53) 3. cert heat loss [(47)×(51)×(52)] ≤ PCDB heat loss All three pass → 0.95; any criterion fails or is unknown → 0.60. The Open EPC API never lodges cylinder heat-exchanger area, so for the cohort this criterion is always "unknown" → in_use_factor = 0.60. Cert 0380 (Mitsubishi ASHP PCDB 104568, ASHP main, 160 L cylinder): cascade PSR = 4.39 / (127.158 × 24.2 / 1000) ≈ 1.4266 cascade η_space,1_interp ≈ 235.24 (PSR-1.2 row 253.9, PSR-1.5 229.2) cascade η_water,3_interp ≈ 285.13 (PSR-1.2 row 287.7, PSR-1.5 284.3) cascade main_heating_eff ≈ 2.2348 (vs worksheet 2.2305, 1.9e-3 diff) cascade HW kWh/yr ≈ 878.05 (vs worksheet 877.97, 0.08 kWh/yr) cascade SAP rating ≈ 89.11 (vs worksheet 88.5104, +0.60) The remaining +0.60 SAP residual is bounded by the ~0.4% PSR-formula drift (the cascade computes PSR=1.4266 from (39)_annual_avg × 24.2 K whereas the worksheet back-solves to ≈ 1.4321). Slice 102f decides whether further PSR refinement is needed to reach a 1e-4 SAP pin.
This commit is contained in:
Khalim Conn-Kowlessar
Jun-te Kim
parent
9950226267
commit
2e5c519861
2 changed files with 194 additions and 0 deletions
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@ -148,6 +148,9 @@ from domain.sap10_calculator.worksheet.ventilation import (
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VentilationResult,
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ventilation_from_inputs,
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)
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from domain.sap10_calculator.tables.pcdb.parser import (
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interpolate_heat_pump_efficiency_at_psr,
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)
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from domain.sap10_calculator.worksheet.water_heating import (
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PIPEWORK_INSULATED_FULLY,
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PIPEWORK_INSULATED_UNINSULATED,
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@ -155,7 +158,9 @@ from domain.sap10_calculator.worksheet.water_heating import (
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WaterHeatingResult,
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combi_loss_monthly_kwh_table_3b_row_1_instantaneous,
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combi_loss_monthly_kwh_table_3c_two_profile_instantaneous,
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cylinder_storage_loss_factor_table_2,
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cylinder_storage_loss_monthly_kwh,
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cylinder_volume_factor_table_2a,
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primary_loss_monthly_kwh,
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water_efficiency_monthly_via_equation_d1,
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water_heating_from_cert,
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@ -1912,6 +1917,115 @@ def _pipework_insulation_fraction_table_3(primary_age: Optional[str]) -> float:
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return PIPEWORK_INSULATED_UNINSULATED
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# SAP 10.2 PDF p.100 line 5950: design heat loss = (39) × ΔT, where ΔT
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# = 24.2 K. The HLC × ΔT product feeds the PSR denominator per line 5946.
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_SAP_DESIGN_HEAT_LOSS_DELTA_T_K: Final[float] = 24.2
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# Cohort-derived in-use factors per SAP 10.2 Appendix N3.6 / N3.7 (PDF
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# p.108 + the cylinder criteria table at p.6097). 0.95 applies only when
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# the cert's cylinder matches the PCDB-lodged volume / heat exchanger
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# area / heat loss; 0.60 otherwise (or when any criterion is unknown).
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_HP_SPACE_HEATING_IN_USE_FACTOR_N3_6: Final[float] = 0.95
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_HP_IN_USE_FACTOR_CRITERIA_MET: Final[float] = 0.95
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_HP_IN_USE_FACTOR_CRITERIA_FAIL: Final[float] = 0.60
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def _heat_pump_cylinder_meets_pcdb_criteria(
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epc: EpcPropertyData,
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hp_record: "HeatPumpRecord",
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) -> bool:
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"""Spec PDF p.6097 — "in-use factor 0.95 applies when the actual
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cylinder has performance parameters at least equal to those in the
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PCDB record, namely:
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- cylinder volume not less than that in the PCDB record
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- heat transfer area not less than that in the PCDB record
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(unless the PCDB heat exchanger area is zero — see footnote 53)
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- heat loss (kWh/day) [either (48) or (47) × (51) × (52)] not
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greater than that in the PCDB record.
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If any of these conditions are not fulfilled, or are unknown, the
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in-use factor is 0.60."
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The Open EPC API does not lodge cylinder heat exchanger area, so
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for the cohort this criterion is always "unknown" → returns False.
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"""
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sh = epc.sap_heating
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size_code = _int_or_none(sh.cylinder_size)
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if size_code is None:
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return False
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cert_volume_l = _CYLINDER_SIZE_CODE_TO_LITRES.get(size_code)
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if cert_volume_l is None:
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return False
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# Volume criterion.
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if hp_record.vessel_volume_l is None or cert_volume_l < hp_record.vessel_volume_l:
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return False
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# Heat exchanger area criterion. The footnote 53 carve-out (PCDB
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# area = 0 → test does not apply) doesn't fire here because cohort
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# records lodge non-zero areas (3.0 m² for 104568 / 0.415 for
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# 102421). Open EPC certs don't lodge HX area → always fail.
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if (
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hp_record.vessel_heat_exchanger_area_m2 is not None
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and hp_record.vessel_heat_exchanger_area_m2 > 0.0
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):
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return False # cert HX area is unknown per API schema → criterion fails
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# Heat loss criterion.
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if sh.cylinder_insulation_type != _CYLINDER_INSULATION_TYPE_FACTORY:
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return False
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thickness_mm = sh.cylinder_insulation_thickness_mm
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if thickness_mm is None:
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return False
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cert_heat_loss_kwh_per_day = (
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cert_volume_l
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* cylinder_storage_loss_factor_table_2(
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insulation_type="factory_insulated",
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thickness_mm=float(thickness_mm),
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)
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* cylinder_volume_factor_table_2a(cert_volume_l)
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)
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pcdb_heat_loss = hp_record.vessel_heat_loss_kwh_per_day
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if pcdb_heat_loss is None or cert_heat_loss_kwh_per_day > pcdb_heat_loss:
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return False
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return True
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def _heat_pump_apm_efficiencies(
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*,
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main: Optional[MainHeatingDetail],
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hp_record: Optional["HeatPumpRecord"],
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hlc_annual_avg_w_per_k: float,
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epc: EpcPropertyData,
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) -> Optional[tuple[float, float]]:
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"""Compute `(main_heating_efficiency, water_efficiency_pct)` per
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SAP 10.2 Appendix N3.6 (space) + N3.7(a) (water, footnote 49).
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Returns None when APM is not applicable (no HP, no PCDB record, no
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PSR groups, no max output) so the caller keeps the Table 4a default.
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"""
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if main is None or main.main_heating_category != 4:
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return None
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if hp_record is None or not hp_record.psr_groups:
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return None
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if hp_record.max_output_kw is None or hp_record.max_output_kw <= 0:
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return None
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if hlc_annual_avg_w_per_k <= 0:
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return None
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psr = (hp_record.max_output_kw * 1000.0) / (
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hlc_annual_avg_w_per_k * _SAP_DESIGN_HEAT_LOSS_DELTA_T_K
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)
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eta_space_1_pct, eta_water_3_pct = interpolate_heat_pump_efficiency_at_psr(
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hp_record.psr_groups, target_psr=psr,
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)
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in_use_water = (
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_HP_IN_USE_FACTOR_CRITERIA_MET
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if _heat_pump_cylinder_meets_pcdb_criteria(epc, hp_record)
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else _HP_IN_USE_FACTOR_CRITERIA_FAIL
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)
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main_heating_efficiency = (
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_HP_SPACE_HEATING_IN_USE_FACTOR_N3_6 * eta_space_1_pct / 100.0
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)
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water_efficiency_pct = in_use_water * eta_water_3_pct / 100.0
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return (main_heating_efficiency, water_efficiency_pct)
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def _primary_loss_applies(
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main: Optional[MainHeatingDetail],
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cylinder_present: bool,
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@ -2320,6 +2434,11 @@ def cert_to_inputs(
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if main is not None and main.main_heating_index_number is not None
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else None
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)
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pcdb_hp_record = (
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heat_pump_record(main.main_heating_index_number)
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if main is not None and main.main_heating_index_number is not None
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else None
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)
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# Heat-network override (Table 12 note (k)) sets efficiency = 1/DLF so
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# `main_fuel_kwh = q_useful × DLF = q_generated`, matching the spec's
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# "unit prices per kWh of heat generated" convention.
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@ -2333,6 +2452,20 @@ def cert_to_inputs(
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main_category=main_category,
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main_fuel=main_fuel,
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)
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# SAP 10.2 Appendix N3.6 + N3.7(a) — when an HP cert lodges a PCDB
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# Table 362 record, the cascade replaces the Table 4a defaults with
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# APM-interpolated η_space and η_water at the dwelling's PSR.
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hlc_annual_avg_w_per_k = ht.total_w_per_k + 0.33 * dim.volume_m3 * sum(
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ventilation.effective_monthly_ach
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) / 12.0
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apm_efficiencies = _heat_pump_apm_efficiencies(
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main=main,
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hp_record=pcdb_hp_record,
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hlc_annual_avg_w_per_k=hlc_annual_avg_w_per_k,
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epc=epc,
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)
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if apm_efficiencies is not None:
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eff, water_eff = apm_efficiencies
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if (
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_is_heat_network_main(main)
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and epc.sap_heating.water_heating_code in _WATER_INHERIT_FROM_MAIN_CODES
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@ -1086,6 +1086,67 @@ def test_cert_with_hot_water_cylinder_computes_storage_loss_56m_from_sap_tables_
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)
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def test_air_source_heat_pump_pcdb_104568_derives_apm_efficiencies_per_sap_app_n() -> None:
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"""SAP 10.2 Appendix N3.6 / N3.7(a) (PDF p.108) replace the Table 4a
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HP defaults with PSR-interpolated efficiencies from the PCDB Table
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362 record:
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(206) = 0.95 × η_space,1_interp (N3.6 in-use factor)
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(217) = in_use_factor × η_water,3_interp (N3.7 + table p.6097)
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For cert 0380 (PCDB index 104568, separate-but-specified vessel,
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cert cylinder 160 L > PCDB 150 L ✓ but heat exchanger area unknown
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AND cert heat loss 2.21 > PCDB 1.86 kWh/day ✗ → 2 criteria fail
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→ in-use factor = 0.60):
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PSR ≈ 4.39 / (127.16 W/K × 24.2 K / 1000) ≈ 1.4266
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η_space,1_interp(1.4266) ≈ 235.24
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η_water,3_interp(1.4266) ≈ 285.13
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(206) ≈ 0.95 × 235.24 / 100 ≈ 2.235
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(217) ≈ 0.60 × 285.13 / 100 ≈ 1.7108
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Worksheet pins (206) = 2.2305 and (217) = 1.7107; the spec-formula
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PSR is within 0.4% of the worksheet-implied 1.4321 — the residual
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propagates through η_space at ~2e-3 (slice 102f decides whether
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further PSR refinement is needed to land SAP at 1e-4).
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HW fuel kWh after applying η_water:
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HW_kwh = output_kwh / η_water = 1502.16 / 1.7108 ≈ 878.05
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Worksheet 877.97 (the cohort's first cert to land HW kWh
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within 1 kWh of the dr87 worksheet pin).
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"""
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# Arrange — cert 0380 golden fixture
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import json
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from pathlib import Path
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from datatypes.epc.domain.mapper import EpcPropertyDataMapper
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from domain.sap10_calculator.rdsap.cert_to_inputs import (
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SAP_10_2_SPEC_PRICES,
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)
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doc = json.loads(
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Path(
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"/workspaces/model/domain/sap10_calculator/rdsap/tests/"
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"fixtures/golden/0380-2471-3250-2596-8761.json"
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).read_text()
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)
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epc = EpcPropertyDataMapper.from_api_response(doc)
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# Act
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inputs = cert_to_inputs(epc, prices=SAP_10_2_SPEC_PRICES)
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# Assert — main heating COP from APM N3.6 (×0.95 in-use factor).
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# Tolerance 1e-2 absorbs the ~0.4% PSR-formula residual vs the
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# worksheet's implied PSR; slice 102f tightens this if necessary.
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assert abs(inputs.main_heating_efficiency - 2.2305) < 1e-2, (
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f"main_heating_efficiency: got {inputs.main_heating_efficiency!r}, "
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f"want ≈ 2.2305 per SAP 10.2 Appendix N3.6 (0.95 × η_space,1_interp)"
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)
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# Assert — HW kWh/yr = output_kwh / η_water lands within 1 kWh of
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# worksheet's 877.97 (the 1502.16 / 1.7107 quotient).
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assert abs(inputs.hot_water_kwh_per_yr - 877.97) < 1.0, (
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f"hot_water_kwh_per_yr: got {inputs.hot_water_kwh_per_yr!r}, "
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f"want ≈ 877.97 per SAP 10.2 §4 (64) ÷ Appendix N3.7(a) η_water,3"
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)
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def test_cert_with_hot_water_cylinder_computes_primary_loss_59m_from_sap_table_3() -> None:
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"""SAP 10.2 §4 line 7700 + Table 3 (PDF p.159) define the primary
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circuit loss for an indirect cylinder:
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