diff --git a/scripts/build_retro_cost.py b/scripts/build_retro_cost.py
index bccea3e4..c9912b2f 100644
--- a/scripts/build_retro_cost.py
+++ b/scripts/build_retro_cost.py
@@ -198,6 +198,8 @@ def prepare_building_stock_data():
         }
     )
 
+    building_data["country_code"] = building_data["country"].map(country_iso_dic)    
+
     # heated floor area ----------------------------------------------------------
     area = building_data[
         (building_data.type == "Heated area [Mm²]")