diff --git a/city_model_structure/city.py b/city_model_structure/city.py
index fb59e91f..07eef224 100644
--- a/city_model_structure/city.py
+++ b/city_model_structure/city.py
@@ -169,7 +169,7 @@ class City:
         self._buildings = []
       self._buildings.append(new_city_object)
     else:
-      raise NotImplementedError
+      raise NotImplementedError(new_city_object.type)
 
   def remove_city_object(self, city_object):
     """
diff --git a/non_functional_tests/test_sensors_factory.py b/non_functional_tests/test_sensors_factory.py
index 9b669eb6..81db502a 100644
--- a/non_functional_tests/test_sensors_factory.py
+++ b/non_functional_tests/test_sensors_factory.py
@@ -39,7 +39,12 @@ class TestSensorsFactory(TestCase):
     buildings.append(Building("EV", lod, surfaces, year_of_construction, function, lower_corner))
     buildings.append(Building("GM", lod, surfaces, year_of_construction, function, lower_corner))
     city = City(lower_corner, upper_corner, srs_name)
-    city.add_city_object(CityObject("GM_MB_EV", lod, surfaces, lower_corner))
+    #virtual_building = CityObject("GM_MB_EV", lod, surfaces, lower_corner)
+    #virtual_building.type = 'Virtual'
+    #city.add_city_object(virtual_building)
+
+    for building in buildings:
+      city.add_city_object(building)
     return city
 
   def test_city_with_sensors(self):
@@ -47,9 +52,7 @@ class TestSensorsFactory(TestCase):
     SensorsFactory('cgf', self._city, self._end_point).enrich()
     SensorsFactory('ct', self._city, self._end_point).enrich()
     for city_object in self._city.city_objects:
-      print(city_object.name)
       for sensor in city_object.sensors:
-        print(sensor.name)
         # force update last row
         update = pd.DataFrame([['2020-01-19 23:55:00', '12345.0']], columns=["Date time", "Energy consumption"])
         update = update.astype({"Date time": 'datetime64', "Energy consumption": 'float64'})