diff --git a/city_model_structure/building.py b/city_model_structure/building.py
index 8af372a3..6ee7477d 100644
--- a/city_model_structure/building.py
+++ b/city_model_structure/building.py
@@ -16,6 +16,7 @@ from city_model_structure.thermal_boundary import ThermalBoundary
 from city_model_structure.thermal_zone import ThermalZone
 from city_model_structure.usage_zone import UsageZone
 from city_model_structure.city_object import CityObject
+from city_model_structure.building_unit import BuildingUnit
 
 
 class Building(CityObject):
@@ -246,7 +247,24 @@ class Building(CityObject):
   @property
   def type(self):
     """
-    City object type
+    building type
     :return: str
     """
     return self._type
+
+  @property
+  def building_units(self) -> [BuildingUnit]:
+    """
+    Building units
+    :return:
+    """
+    return self._building_units
+
+  @building_units.setter
+  def building_units(self, value):
+    """
+    Building units
+    :param value: [BuildingUnit]
+    :return: List of building units
+    """
+    self._building_units = value
diff --git a/city_model_structure/building_unit.py b/city_model_structure/building_unit.py
new file mode 100644
index 00000000..bcc3b345
--- /dev/null
+++ b/city_model_structure/building_unit.py
@@ -0,0 +1,48 @@
+"""
+Building module
+SPDX - License - Identifier: LGPL - 3.0 - or -later
+Copyright © 2020 Project Author Guille Gutierrez guillermo.gutierrezmorote@concordia.ca
+"""
+from builtins import float
+
+from city_model_structure.city_object import CityObject
+
+
+class BuildingUnit(CityObject):
+  """
+  BuildingUnit class
+  """
+
+  def __init__(self, number_of_rooms, floor_area, energy_certificate):
+    """
+    Constructor
+    """
+    self._number_of_rooms = number_of_rooms
+    self._floor_area = floor_area
+    self._energy_certificate = energy_certificate
+
+  @property
+  def number_of_rooms(self):
+    """
+    Get building unit number of rooms
+    :return: number of rooms
+    """
+    return self._number_of_rooms
+
+  @property
+  def floor_area(self):
+    """
+    Building unit floor area in square meters
+    :return: float
+    """
+    return self._floor_area
+
+  @property
+  def energy_certificate(self):
+    """
+    Building unit energy certificate
+    :return: energy_certificate
+    """
+    #TODO: This is still not used, check in the future
+    return self._energy_certificate
+