diff --git a/hub_api/mockup/building.py b/hub_api/mockup/building.py
index 8aebfb4..a329a33 100644
--- a/hub_api/mockup/building.py
+++ b/hub_api/mockup/building.py
@@ -29,7 +29,7 @@ class Building:
                heating_peak_load,
                cooling_peak_load,
                onsite_electrical_production,
-               catalog_energy_systems):
+               catalog_archetype):
     self._function = function
     self._area = area
     self._volume = volume
@@ -46,7 +46,7 @@ class Building:
     self._heating_peak_load = heating_peak_load
     self._cooling_peak_load = cooling_peak_load
     self._onsite_electrical_production = onsite_electrical_production
-    self._catalog_energy_systems = catalog_energy_systems
+    self._catalog_archetype = catalog_archetype
 
   @property
   def function(self):
@@ -117,9 +117,10 @@ class Building:
   @property
   def energy_systems(self):
     _energy_systems = []
-    for value in self._catalog_energy_systems:
-      demands = value[0]
-      fuel_type = value[1]
+
+    for system in self._catalog_archetype.systems:
+      demands = system.demand_types
+      fuel_type = system.generation_system.fuel_type
       generic_generation_system = GenericGenerationSystem()
       generic_generation_system.fuel_type = fuel_type
       generation_system = GenerationSystem()