diff --git a/hub/city_model_structure/building_demand/internal_zone.py b/hub/city_model_structure/building_demand/internal_zone.py
index 8bf2c98b..77d524a7 100644
--- a/hub/city_model_structure/building_demand/internal_zone.py
+++ b/hub/city_model_structure/building_demand/internal_zone.py
@@ -132,6 +132,8 @@ class InternalZone:
       _thermal_boundary = ThermalBoundary(surface, surface.solid_polygon.area, windows_areas)
       surface.associated_thermal_boundaries = [_thermal_boundary]
       _thermal_boundaries.append(_thermal_boundary)
+    if self.thermal_archetype is None:
+      return None  # there are no archetype
     _number_of_storeys = int(self.volume / self.area / self.thermal_archetype.average_storey_height)
     _thermal_zone = ThermalZone(_thermal_boundaries, self, self.volume, self.area, _number_of_storeys)
     for thermal_boundary in _thermal_zone.thermal_boundaries:
diff --git a/hub/exports/building_energy/idf.py b/hub/exports/building_energy/idf.py
index 55faa89c..3f713be3 100644
--- a/hub/exports/building_energy/idf.py
+++ b/hub/exports/building_energy/idf.py
@@ -513,7 +513,7 @@ class Idf:
     self._lod = self._city.level_of_detail.geometry
     for building in self._city.buildings:
       for internal_zone in building.internal_zones:
-        if internal_zone.thermal_zones_from_internal_zones is None or len(internal_zone.thermal_zones_from_internal_zones.thermal_boundaries) == 0:
+        if internal_zone.thermal_zones_from_internal_zones is None:
           self._add_shading(building)  # if the building has not archetype use it as shadow object
           continue
         for thermal_zone in internal_zone.thermal_zones_from_internal_zones: