diff --git a/hub/city_model_structure/city.py b/hub/city_model_structure/city.py
index 03764570..7934c924 100644
--- a/hub/city_model_structure/city.py
+++ b/hub/city_model_structure/city.py
@@ -29,6 +29,7 @@ from hub.helpers.geometry_helper import GeometryHelper
 from hub.helpers.location import Location
 from hub.city_model_structure.energy_system import EnergySystem
 from hub.city_model_structure.lca_material import LcaMaterial
+import pandas as pd
 
 
 class City:
@@ -447,8 +448,25 @@ class City:
 
   def merge(self, city) -> City:
     _merge_city = self.copy
+    selected_city_object = None
+    # set initial minimum radiation to a higher number
+    min_radiation = 1000000
     for city_object in city.city_objects:
-      _merge_city.add_city_object(city_object)
+      if city_object.type == 'building':
+        building_radiation = 0
+        for surface in city_object.surfaces:
+          radiation = surface.global_irradiance
+          if "yearly" in radiation:
+              building_radiation += radiation["yearly"].iloc[0]
+          elif "monthly" in radiation and "yearly" not in radiation:
+            radiation["yearly"] = pd.DataFrame({radiation["monthly"].sum()})
+            building_radiation += radiation["yearly"].iloc[0]
+        if building_radiation < min_radiation:
+          min_radiation = building_radiation
+          selected_city_object = city_object
+    # merge the city object with the minimum radiation
+    if selected_city_object is not None:
+      _merge_city.add_city_object(selected_city_object)
     return _merge_city
 
   @property
diff --git a/hub/imports/db_factory.py b/hub/imports/db_factory.py
index 596aa225..67891f30 100644
--- a/hub/imports/db_factory.py
+++ b/hub/imports/db_factory.py
@@ -51,4 +51,4 @@ class DBFactory:
     :param city_id: city id or None
     :param city_object_id: city object id or None
     """
-    self._simulation_results.insert(name, values,city_id, city_object_id)
+    self._simulation_results.insert(name, values, city_id, city_object_id)