diff --git a/hub_api/mockup/building.py b/hub_api/mockup/building.py
index b7c68f5..466742d 100644
--- a/hub_api/mockup/building.py
+++ b/hub_api/mockup/building.py
@@ -20,7 +20,7 @@ class Building:
     self._wall_area = building_info.wall_area
     self._windows_area = building_info.windows_area
     self._roof_area = building_info.roof_area
-    self._solar_collectors_area_reduction_factor = building_info.total_pv_area
+    self._total_pv_area = building_info.total_pv_area
     self._heating_consumption = building_info.heating_consumption
     self._cooling_consumption = building_info.cooling_consumption
     self._domestic_hot_water_consumption = building_info.domestic_hot_water_consumption
@@ -62,7 +62,7 @@ class Building:
     polygon.area = self._roof_area
     roof = Roof()
     roof.solid_polygon = polygon
-    roof.solar_collectors_area_reduction_factor = self._solar_collectors_area_reduction_factor
+    roof.solar_collectors_area_reduction_factor = self._total_pv_area / self._roof_area
     return [roof]
 
   @property