diff --git a/backend/app/db/models/materials.py b/backend/app/db/models/materials.py
index 347b66d5..9b38addd 100644
--- a/backend/app/db/models/materials.py
+++ b/backend/app/db/models/materials.py
@@ -19,6 +19,7 @@ class MaterialType(enum.Enum):
     flat_roof_insulation = "flat_roof_insulation"
     room_roof_insulation = "room_roof_insulation"
     windows_glazing = "windows_glazing"
+    secondary_glazing = "secondary_glazing"
     cavity_wall_extraction = "cavity_wall_extraction"
 
     iwi_wall_demolition = "iwi_wall_demolition"
diff --git a/backend/engine/engine.py b/backend/engine/engine.py
index f2674290..f4152852 100644
--- a/backend/engine/engine.py
+++ b/backend/engine/engine.py
@@ -959,15 +959,19 @@ async def model_engine(body: PlanTriggerRequest):
                 )
 
                 # Given the solutions we select the optimal one
+                # 1) If the scheme is ECO4, the full project funding and uplift are deducted from the cost
+                # 2) If the sheme is GBIS, the partial project funding and uplift are deducted from the cost
+                # 3) Otherwise, no funding is deducted from the cost
                 solutions["cost_less_full_project_funding"] = np.where(
-                    solutions["scheme"] == "eco4",
-                    solutions["total_cost"] - solutions["full_project_funding"] - solutions["total_uplift"],
-                    solutions["total_cost"] - solutions["partial_project_funding"] - solutions["total_uplift"]
+                    solutions["scheme"] == "none",
+                    solutions["total_cost"],
+                    np.where(
+                        solutions["scheme"] == "eco4",
+                        solutions["total_cost"] - solutions["full_project_funding"] - solutions["total_uplift"],
+                        solutions["total_cost"] - solutions["partial_project_funding"] - solutions["total_uplift"]
+                    )
                 )
 
-                solutions["cost_less_full_project_funding"] = (
-                    solutions["total_cost"] - solutions["full_project_funding"] - solutions["total_uplift"]
-                )
                 solutions = solutions.sort_values("cost_less_full_project_funding", ascending=True)
 
                 if solutions["meets_upgrade_target"].any():