§5 slice 7: (70) pumps_fans_monthly_w — Table 5a 9-row dispatch

Implements Table 5a row-by-row leaf functions:
  central_heating_pump_w     pump install-date bucket (3/7/10 W)
  liquid_fuel_boiler_pump_w  10 W when oil-fuel pump inside dwelling
  liquid_fuel_warm_air_pump_w  10 W for liquid-fuel warm-air systems
  warm_air_heating_fan_w     SFP × 0.04 × V (heating-season)
  piv_fan_w                  IUF × SFP × 0.12 × V (year-round)
  balanced_mv_no_hr_fan_w    IUF × SFP × 0.06 × V (year-round)
  heat_interface_unit_w      PCDB kWh/day × 1000 / 24 (year-round)

Plus pumps_fans_monthly_w(heating_season_w, year_round_w) which applies
the Table 5a footnote-a seasonal mask (Jun-Sep = 0 W heating-season
contribution per Elmhurst worksheet convention).

PumpDateCategory enum maps from EpcPropertyData.central_heating_pump_age_str
("Pre 2013" / "Post 2013" / "Unknown" / etc.) at the orchestrator layer.

MVHR and MEV systems intentionally have no leaf fn — gains are zero per
Table 5a notes (MVHR effect is in MVHR efficiency; MEV simply omitted).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

packages/domain/src/domain/sap/worksheet/internal_gains.py

@@ -27,6 +27,7 @@ Appendix J Table 1b (occupancy from TFA).
 from __future__ import annotations
 
 from dataclasses import dataclass
+from enum import Enum
 from math import cos, exp, pi
 from typing import Final, Optional
 
@@ -36,6 +37,29 @@ _APPLIANCES_E_A_EXPONENT: Final[float] = 0.4714
 _APPLIANCES_MONTHLY_AMPLITUDE: Final[float] = 0.157
 _APPLIANCES_MONTHLY_PHASE: Final[float] = 1.78
 
+# Table 5a constants.
+_PUMP_W_NEW_2013_OR_LATER: Final[float] = 3.0
+_PUMP_W_OLD_2012_OR_EARLIER: Final[float] = 10.0
+_PUMP_W_UNKNOWN_DATE: Final[float] = 7.0
+_LIQUID_FUEL_BOILER_PUMP_W: Final[float] = 10.0
+_LIQUID_FUEL_WARM_AIR_PUMP_W: Final[float] = 10.0
+_WARM_AIR_HEATING_VOLUME_COEFF: Final[float] = 0.04
+_PIV_VOLUME_COEFF: Final[float] = 0.12
+_BALANCED_MV_NO_HR_VOLUME_COEFF: Final[float] = 0.06
+_HIU_HOURS_PER_DAY: Final[float] = 24.0
+_SUMMER_MONTHS: Final[frozenset[int]] = frozenset({6, 7, 8, 9})
+
+
+class PumpDateCategory(Enum):
+    """Pump install-date bucket per Table 5a, used to dispatch the central
+    heating pump wattage. Maps from the cert's `central_heating_pump_age_str`
+    field (Elmhurst lodges "Pre 2013" / "Post 2013" / "Unknown")."""
+
+    NEW_2013_OR_LATER = "new"
+    OLD_2012_OR_EARLIER = "old"
+    UNKNOWN = "unknown"
+
+
 # Appendix L lighting constants.
 _LIGHTING_LAMBDA_B_COEFF: Final[float] = 11.2 * 59.73
 _LIGHTING_LAMBDA_B_EXPONENT: Final[float] = 0.4714
@@ -181,6 +205,98 @@ def lighting_monthly_w(
     return tuple(monthly)
 
 
+def central_heating_pump_w(*, date_category: PumpDateCategory) -> float:
+    """Table 5a row "Central heating pump in heated space". Pump wattage
+    depends on install-date bucket: 3 W for 2013+, 10 W for ≤2012, 7 W
+    for unknown date. Applies only in heating-season months (caller
+    applies seasonal mask via `pumps_fans_monthly_w`)."""
+    if date_category is PumpDateCategory.NEW_2013_OR_LATER:
+        return _PUMP_W_NEW_2013_OR_LATER
+    if date_category is PumpDateCategory.OLD_2012_OR_EARLIER:
+        return _PUMP_W_OLD_2012_OR_EARLIER
+    return _PUMP_W_UNKNOWN_DATE
+
+
+def liquid_fuel_boiler_pump_w() -> float:
+    """Table 5a row "Liquid fuel boiler pump, inside dwelling": 10 W.
+    Additive to central heating pump per footnote (b)."""
+    return _LIQUID_FUEL_BOILER_PUMP_W
+
+
+def liquid_fuel_warm_air_pump_w() -> float:
+    """Table 5a row "Liquid-fuel-fired warm air system, inside dwelling": 10 W."""
+    return _LIQUID_FUEL_WARM_AIR_PUMP_W
+
+
+def warm_air_heating_fan_w(
+    *,
+    sfp_w_per_l_per_s: float,
+    dwelling_volume_m3: float,
+) -> float:
+    """Table 5a row "Warm air heating system fans": SFP × 0.04 × V (W).
+    SFP defaults to 1.5 W/(l/s) when PCDB data is unknown (footnote c)."""
+    return sfp_w_per_l_per_s * _WARM_AIR_HEATING_VOLUME_COEFF * dwelling_volume_m3
+
+
+def piv_fan_w(
+    *,
+    in_use_factor: float,
+    sfp_w_per_l_per_s: float,
+    dwelling_volume_m3: float,
+) -> float:
+    """Table 5a row "Fans for positive input ventilation from outside":
+    IUF × SFP × 0.12 × V (W). Year-round contribution."""
+    return (
+        in_use_factor
+        * sfp_w_per_l_per_s
+        * _PIV_VOLUME_COEFF
+        * dwelling_volume_m3
+    )
+
+
+def balanced_mv_no_hr_fan_w(
+    *,
+    in_use_factor: float,
+    sfp_w_per_l_per_s: float,
+    dwelling_volume_m3: float,
+) -> float:
+    """Table 5a row "Fans for balanced whole house mechanical ventilation
+    without heat recovery": IUF × SFP × 0.06 × V (W). Year-round."""
+    return (
+        in_use_factor
+        * sfp_w_per_l_per_s
+        * _BALANCED_MV_NO_HR_VOLUME_COEFF
+        * dwelling_volume_m3
+    )
+
+
+def heat_interface_unit_w(*, electricity_kwh_per_day: float) -> float:
+    """Table 5a row "Electricity use by heat interface unit": PCDB entry
+    (kWh/day) × 1000 / 24 → constant W year-round."""
+    return electricity_kwh_per_day * _KWH_TO_WH / _HIU_HOURS_PER_DAY
+
+
+def pumps_fans_monthly_w(
+    *,
+    heating_season_w: float,
+    year_round_w: float,
+) -> tuple[float, ...]:
+    """SAP10.2 §5 line (70) — pumps and fans gains in W per month.
+
+    Combines Table 5a contributions split by seasonal mode:
+      heating-season-only (footnote a/b): pump rows + warm-air fans
+      year-round: PIV, balanced MV w/o HR, HIU electricity
+
+    Summer = June-September inclusive (months 6-9). Mirrors the Elmhurst
+    worksheet convention visible across all 6 U985 fixtures.
+    """
+    return tuple(
+        (heating_season_w + year_round_w) if m not in _SUMMER_MONTHS
+        else year_round_w
+        for m in range(1, _MONTHS_IN_YEAR + 1)
+    )
+
+
 def water_heating_gains_monthly_w(
     *,
     heat_gains_from_water_heating_monthly_kwh: tuple[float, ...],

packages/domain/src/domain/sap/worksheet/tests/test_internal_gains.py

@@ -13,11 +13,20 @@ Table 5a + Appendix L (lighting/appliances/cooking) + Appendix J Table 1b
 import pytest
 
 from domain.sap.worksheet.internal_gains import (
+    PumpDateCategory,
     appliances_monthly_w,
+    balanced_mv_no_hr_fan_w,
+    central_heating_pump_w,
     cooking_monthly_w,
+    heat_interface_unit_w,
     lighting_monthly_w,
+    liquid_fuel_boiler_pump_w,
+    liquid_fuel_warm_air_pump_w,
     losses_monthly_w,
     metabolic_monthly_w,
+    piv_fan_w,
+    pumps_fans_monthly_w,
+    warm_air_heating_fan_w,
     water_heating_gains_monthly_w,
 )
 
@@ -205,3 +214,133 @@ def test_lighting_gains_match_appendix_l1_l12_for_000490() -> None:
     assert len(monthly) == 12
     for m, (actual, exp) in enumerate(zip(monthly, expected_w)):
         assert actual == pytest.approx(exp, abs=5e-3), f"month {m+1}"
+
+
+def test_pumps_fans_seasonal_mask_zeroes_summer_months_jun_to_sep() -> None:
+    """SAP10.2 Table 5a footnote a/b: pumps and warm-air fans are "Set to
+    zero in summer months". Year-round contributions (PIV, balanced MV
+    without HR, HIU) are unaffected.
+
+    Defines "summer" as June-September inclusive (months 6-9), the
+    Elmhurst worksheet convention visible across all 6 U985 fixtures
+    where (70)m shows 7W Oct-May and 0W Jun-Sep.
+    """
+    # Arrange
+    heating_season_w = 7.0   # central heating pump unknown date
+    year_round_w = 0.0       # no PIV/MV/HIU
+
+    # Act
+    monthly = pumps_fans_monthly_w(
+        heating_season_w=heating_season_w,
+        year_round_w=year_round_w,
+    )
+
+    # Assert — heating season Oct-May = 7W; summer Jun-Sep = 0W
+    expected = (7.0, 7.0, 7.0, 7.0, 7.0, 0.0, 0.0, 0.0, 0.0, 7.0, 7.0, 7.0)
+    assert monthly == pytest.approx(expected, abs=1e-9)
+
+
+def test_pumps_fans_year_round_w_persists_through_summer() -> None:
+    """Table 5a row d) (PIV / balanced MV w/o HR) and HIU electricity
+    are not marked with footnote (a) — they run year-round. Heating-
+    season-only contributions add on top during Oct-May."""
+    # Arrange
+    heating_season_w = 7.0
+    year_round_w = 25.0  # e.g. balanced MV w/o HR fan
+
+    # Act
+    monthly = pumps_fans_monthly_w(
+        heating_season_w=heating_season_w,
+        year_round_w=year_round_w,
+    )
+
+    # Assert
+    expected = (32.0, 32.0, 32.0, 32.0, 32.0, 25.0, 25.0, 25.0, 25.0, 32.0, 32.0, 32.0)
+    assert monthly == pytest.approx(expected, abs=1e-9)
+
+
+def test_central_heating_pump_returns_7w_for_unknown_install_date() -> None:
+    """Table 5a row "Central heating pump in heated space, unknown date":
+    7 W. The modal lodging across the 6 Elmhurst fixtures."""
+    # Arrange / Act
+    w = central_heating_pump_w(date_category=PumpDateCategory.UNKNOWN)
+
+    # Assert
+    assert w == 7.0
+
+
+def test_central_heating_pump_returns_3w_for_2013_or_later() -> None:
+    """Table 5a row "Central heating pump in heated space, 2013 or later": 3 W."""
+    assert central_heating_pump_w(date_category=PumpDateCategory.NEW_2013_OR_LATER) == 3.0
+
+
+def test_central_heating_pump_returns_10w_for_2012_or_earlier() -> None:
+    """Table 5a row "Central heating pump in heated space, 2012 or earlier": 10 W."""
+    assert central_heating_pump_w(date_category=PumpDateCategory.OLD_2012_OR_EARLIER) == 10.0
+
+
+def test_liquid_fuel_boiler_pump_inside_dwelling_is_10w() -> None:
+    """Table 5a row "Liquid fuel boiler pump, inside dwelling": 10 W.
+    Additive to central heating pump per footnote (b)."""
+    assert liquid_fuel_boiler_pump_w() == 10.0
+
+
+def test_liquid_fuel_warm_air_system_inside_is_10w() -> None:
+    """Table 5a row "Liquid-fuel-fired warm air system, inside dwelling": 10 W."""
+    assert liquid_fuel_warm_air_pump_w() == 10.0
+
+
+def test_warm_air_heating_fan_uses_sfp_times_004_times_volume() -> None:
+    """Table 5a row "Warm air heating system fans": SFP × 0.04 × V where
+    V is dwelling volume m³ and SFP defaults to 1.5 W/(l/s) when PCDB
+    data is absent (footnote c)."""
+    # Arrange
+    sfp = 1.5
+    volume_m3 = 250.0
+
+    # Act
+    w = warm_air_heating_fan_w(sfp_w_per_l_per_s=sfp, dwelling_volume_m3=volume_m3)
+
+    # Assert
+    assert w == pytest.approx(1.5 * 0.04 * 250.0, abs=1e-9)  # = 15.0 W
+
+
+def test_piv_fan_uses_iuf_times_sfp_times_012_times_volume() -> None:
+    """Table 5a row "Fans for positive input ventilation from outside":
+    IUF × SFP × 0.12 × V. Footnote (d): SFP in W/(l/s), IUF is in-use
+    factor."""
+    # Arrange / Act
+    w = piv_fan_w(
+        in_use_factor=1.6,
+        sfp_w_per_l_per_s=0.8,
+        dwelling_volume_m3=250.0,
+    )
+
+    # Assert
+    assert w == pytest.approx(1.6 * 0.8 * 0.12 * 250.0, abs=1e-9)
+
+
+def test_balanced_mv_no_hr_fan_uses_iuf_times_sfp_times_006_times_volume() -> None:
+    """Table 5a row "Fans for balanced whole house mechanical ventilation
+    without heat recovery": IUF × SFP × 0.06 × V."""
+    # Arrange / Act
+    w = balanced_mv_no_hr_fan_w(
+        in_use_factor=2.0,
+        sfp_w_per_l_per_s=1.2,
+        dwelling_volume_m3=250.0,
+    )
+
+    # Assert
+    assert w == pytest.approx(2.0 * 1.2 * 0.06 * 250.0, abs=1e-9)
+
+
+def test_heat_interface_unit_converts_kwh_per_day_to_constant_watts() -> None:
+    """Table 5a row "Electricity use by heat interface unit": PCDB entry
+    kWh/day × 1000 / 24 → W constant. For an HIU lodging 0.48 kWh/day:
+        0.48 × 1000 / 24 = 20 W constant
+    """
+    # Arrange / Act
+    w = heat_interface_unit_w(electricity_kwh_per_day=0.48)
+
+    # Assert
+    assert w == pytest.approx(20.0, abs=1e-9)