Model/domain/sap10_ml/tests/test_ventilation.py

"""Tests for ventilation_heat_loss_w_per_k.

SAP10.2 §C + RdSAP10 §5 / Table 5: air change rate per hour (ACH) from
structural infiltration + openings minus draught-proofing reduction, then
W/K = ACH * volume_m3 * 0.33. Volume is total floor area * average storey
height. Open chimneys, blocked chimneys, and flueless gas fires contribute
fixed m³/h additions; draught-proofed windows reduce the structural baseline.
"""

import pytest

from domain.sap10_ml.ventilation import ventilation_heat_loss_w_per_k


def test_ventilation_bare_masonry_no_openings_returns_structural_baseline_only() -> None:
    # Arrange — 80 m² × 2.5 m = 200 m³, masonry struct ACH = 0.35,
    # 100% draught-proofed windows -> 0.05 reduction => 0.30 ACH total.
    # 0.30 * 200 * 0.33 = 19.8 W/K.

    # Act
    result = ventilation_heat_loss_w_per_k(
        total_floor_area_m2=80.0,
        avg_room_height_m=2.5,
        is_timber_frame=False,
        open_chimneys_count=0,
        window_pct_draught_proofed=100.0,
    )

    # Assert
    assert result == pytest.approx(19.8, abs=0.5)


def test_ventilation_timber_frame_no_openings_lower_struct_baseline() -> None:
    # Arrange — same volume but timber frame -> struct ACH = 0.25.
    # 100% DP -> 0.20 ACH; 0.20 * 200 * 0.33 = 13.2 W/K.

    # Act
    result = ventilation_heat_loss_w_per_k(
        total_floor_area_m2=80.0,
        avg_room_height_m=2.5,
        is_timber_frame=True,
        open_chimneys_count=0,
        window_pct_draught_proofed=100.0,
    )

    # Assert
    assert result == pytest.approx(13.2, abs=0.5)


def test_ventilation_open_chimney_adds_40_m3_per_h() -> None:
    # Arrange — masonry, 100% DP (0.30 base ACH), one open chimney adds 40 m³/h.
    # In 200 m³ volume that's 0.20 ACH, so total = 0.50.
    # 0.50 * 200 * 0.33 = 33.0 W/K.

    # Act
    result = ventilation_heat_loss_w_per_k(
        total_floor_area_m2=80.0,
        avg_room_height_m=2.5,
        is_timber_frame=False,
        open_chimneys_count=1,
        window_pct_draught_proofed=100.0,
    )

    # Assert
    assert result == pytest.approx(33.0, abs=0.5)


def test_ventilation_no_draught_proofing_raises_structural_share() -> None:
    # Arrange — masonry, 0% DP -> 0.35 ACH unreduced; no openings.
    # 0.35 * 200 * 0.33 = 23.1 W/K.

    # Act
    result = ventilation_heat_loss_w_per_k(
        total_floor_area_m2=80.0,
        avg_room_height_m=2.5,
        is_timber_frame=False,
        open_chimneys_count=0,
        window_pct_draught_proofed=0.0,
    )

    # Assert
    assert result == pytest.approx(23.1, abs=0.5)


def test_ventilation_heritage_home_with_two_chimneys_and_no_dp() -> None:
    # Arrange — catastrophic heritage profile: TFA 100, room_h 2.5 (vol 250),
    # masonry, 2 open chimneys (80 m³/h), 0% draught-proofed.
    # struct=0.35, openings=80/250=0.32, total=0.67 ACH.
    # 0.67 * 250 * 0.33 = 55.3 W/K.

    # Act
    result = ventilation_heat_loss_w_per_k(
        total_floor_area_m2=100.0,
        avg_room_height_m=2.5,
        is_timber_frame=False,
        open_chimneys_count=2,
        window_pct_draught_proofed=0.0,
    )

    # Assert
    assert result == pytest.approx(55.3, abs=1.0)


def test_ventilation_returns_zero_when_floor_area_is_zero() -> None:
    # Arrange — no volume, no air loss.

    # Act
    result = ventilation_heat_loss_w_per_k(
        total_floor_area_m2=0.0,
        avg_room_height_m=2.5,
        is_timber_frame=False,
        open_chimneys_count=1,
        window_pct_draught_proofed=0.0,
    )

    # Assert
    assert result == 0.0


def test_ventilation_handles_null_chimney_count_as_zero() -> None:
    # Arrange — open_chimneys_count is None on ~70% of the corpus; treat as 0.

    # Act
    result = ventilation_heat_loss_w_per_k(
        total_floor_area_m2=80.0,
        avg_room_height_m=2.5,
        is_timber_frame=False,
        open_chimneys_count=None,
        window_pct_draught_proofed=100.0,
    )

    # Assert — same as zero-chimney case (19.8 W/K).
    assert result == pytest.approx(19.8, abs=0.5)


def test_ventilation_handles_null_dp_share_as_zero() -> None:
    # Arrange — null draught-proofing share treated as no draught-proofing.

    # Act
    result = ventilation_heat_loss_w_per_k(
        total_floor_area_m2=80.0,
        avg_room_height_m=2.5,
        is_timber_frame=False,
        open_chimneys_count=0,
        window_pct_draught_proofed=None,
    )

    # Assert — falls back to full 0.35 struct ACH -> 23.1 W/K.
    assert result == pytest.approx(23.1, abs=0.5)