diff --git a/hub/exports/building_energy/idf.py b/hub/exports/building_energy/idf.py
index 514f6ae4..55faa89c 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(thermal_zone.thermal_boundaries) == 0:
+        if internal_zone.thermal_zones_from_internal_zones is None or len(internal_zone.thermal_zones_from_internal_zones.thermal_boundaries) == 0:
           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: