diff --git a/applications/audit_generator/d1_ventilation_template.xlsx b/applications/audit_generator/d1_ventilation_template.xlsx
index 057da026..f42272e0 100644
Binary files a/applications/audit_generator/d1_ventilation_template.xlsx and b/applications/audit_generator/d1_ventilation_template.xlsx differ
diff --git a/orchestration/audit_generator_orchestrator.py b/orchestration/audit_generator_orchestrator.py
index 1cea614f..a22979c4 100644
--- a/orchestration/audit_generator_orchestrator.py
+++ b/orchestration/audit_generator_orchestrator.py
@@ -7,6 +7,10 @@ from pathlib import Path
 from typing import TYPE_CHECKING, Any, cast
 
 import openpyxl
+from openpyxl.cell.rich_text import CellRichText, TextBlock
+from openpyxl.cell.text import InlineFont
+from openpyxl.formatting.rule import CellIsRule  # type: ignore[reportUnknownVariableType]
+from openpyxl.styles import Color, Font
 
 from domain.magicplan.models import Door, Plan, Room, Window
 from infrastructure.postgres.uploaded_file_table import (
@@ -23,6 +27,26 @@ _TEMPLATE_PATH = Path(__file__).parent.parent / "applications" / "audit_generato
 _SHEET_NAME = "D1 Ventilation"
 _DATA_START_ROW = 6
 _MAX_ROWS = 50
+_Y_CF_RANGE = f"Y{_DATA_START_ROW}:Y{_DATA_START_ROW + _MAX_ROWS - 1}"
+_Y_THRESHOLD = 7600
+_Y_HEADER = CellRichText(
+    TextBlock(InlineFont(b=True, sz=11, rFont="Aptos Narrow"), "Area (mm2)\n"),
+    TextBlock(InlineFont(b=True, sz=11, color=Color(rgb="FF0000"), rFont="Aptos Narrow"), "<"),
+    TextBlock(InlineFont(b=True, sz=11, rFont="Aptos Narrow"), "  7600  "),
+    TextBlock(InlineFont(b=True, sz=11, color=Color(rgb="196B24"), rFont="Aptos Narrow"), "<"),
+)
+
+
+def _apply_column_y_formatting(sheet: Any) -> None:
+    sheet.conditional_formatting.add(
+        _Y_CF_RANGE,
+        CellIsRule(operator="lessThan", formula=[str(_Y_THRESHOLD)], font=Font(color=Color(rgb="FF0000"))),
+    )
+    sheet.conditional_formatting.add(
+        _Y_CF_RANGE,
+        CellIsRule(operator="greaterThan", formula=[str(_Y_THRESHOLD)], font=Font(color=Color(rgb="196B24"))),
+    )
+    sheet["Y3"] = _Y_HEADER
 
 
 def _write_cell(sheet: Any, row: int, col: str, value: Any) -> None:
@@ -75,6 +99,8 @@ def _populate_sheet(sheet: Any, plan: Plan) -> None:
         _write_cell(sheet, row, "X", vent.undercut_mm if vent else 0)
         # Y = formula =W*X — do not write
 
+    _apply_column_y_formatting(sheet)
+
 
 def _serialise_workbook(wb: Any) -> bytes:
     buf = BytesIO()