diff --git a/city_model_structure/building.py b/city_model_structure/building.py
index 1b148fff..b985383e 100644
--- a/city_model_structure/building.py
+++ b/city_model_structure/building.py
@@ -58,8 +58,6 @@ class Building(CityObject):
       else:
         self._internal_walls.append(surface)
 
-    self._pv_plus_hp_installation = None
-
   @property
   def grounds(self) -> [Surface]:
     """