diff --git a/hub/city_model_structure/building.py b/hub/city_model_structure/building.py
index 8d8b5ea3..2ef73469 100644
--- a/hub/city_model_structure/building.py
+++ b/hub/city_model_structure/building.py
@@ -744,15 +744,18 @@ class Building(CityObject):
     if self.energy_systems is None:
       return None
     for energy_system in self.energy_systems:
+      generation_systems = energy_system.generation_system
       for demand_type in energy_system.demand_types:
         if demand_type.lower() == consumption_type.lower():
           if consumption_type in (cte.HEATING, cte.DOMESTIC_HOT_WATER):
-            coefficient_of_performance = energy_system.generation_system.generic_generation_system.heat_efficiency
+            for generation_system in generation_systems:
+              coefficient_of_performance = generation_system.generic_generation_system.heat_efficiency
           elif consumption_type == cte.COOLING:
-            coefficient_of_performance = energy_system.generation_system.generic_generation_system.cooling_efficiency
+            for generation_system in generation_systems:
+              coefficient_of_performance = generation_system.generic_generation_system.cooling_efficiency
           elif consumption_type == cte.ELECTRICITY:
-            coefficient_of_performance = \
-              energy_system.generation_system.generic_generation_system.electricity_efficiency
+            for generation_system in generation_systems:
+              coefficient_of_performance = generation_system.generic_generation_system.electricity_efficiency
     if coefficient_of_performance == 0:
       values = [0]*len(demand)
       final_energy_consumed = values
diff --git a/tests/test_systems_factory.py b/tests/test_systems_factory.py
index 92625adf..4dd70998 100644
--- a/tests/test_systems_factory.py
+++ b/tests/test_systems_factory.py
@@ -161,16 +161,20 @@ class TestSystemsFactory(TestCase):
 
           _building_distribution_system = DistributionSystem()
           _building_distribution_system.generic_distribution_system = (
-            copy.deepcopy(_generic_building_energy_system.distribution_systems)
+            copy.deepcopy(_generic_building_energy_system.distribution_system)
           )
           _building_emission_system = EmissionSystem()
           _building_emission_system.generic_emission_system = (
-            copy.deepcopy(_generic_building_energy_system.emission_systems)
+            copy.deepcopy(_generic_building_energy_system.emission_system)
           )
           _building_generation_system = GenerationSystem()
           _building_generation_system.generic_generation_system = (
             copy.deepcopy(_generic_building_energy_system.generation_system)
           )
+          _building_storage_system = ThermalStorageSystem()
+          _building_storage_system.generic_storage_system = \
+            copy.deepcopy(_generic_building_energy_system.energy_storage_system)
+
           if cte.HEATING in _building_energy_equipment.demand_types:
             _building_generation_system.heat_power = building.heating_peak_load[cte.YEAR][0]
           if cte.COOLING in _building_energy_equipment.demand_types: