diff --git a/backend/engine/engine.py b/backend/engine/engine.py
index dd0aebe4..101f6ada 100644
--- a/backend/engine/engine.py
+++ b/backend/engine/engine.py
@@ -1053,6 +1053,7 @@ async def model_engine(body: PlanTriggerRequest):
             property_required_measures = [m for m in recommendations[p.id] if m[0]["type"] in body.required_measures]
             measures_to_optimise = [m for m in recommendations[p.id] if m[0]["type"] not in body.required_measures]
 
+            # TODO - formalise property measure types into an enum
             ventilation_included = (
                 "ventilation" in property_measure_types or "mechanical_ventilation" in property_measure_types
             )