diff --git a/city_model_structure/attributes/polygon.py b/city_model_structure/attributes/polygon.py
index 08584db2..a745b191 100644
--- a/city_model_structure/attributes/polygon.py
+++ b/city_model_structure/attributes/polygon.py
@@ -15,18 +15,27 @@ class Polygon:
   Polygon class
   """
 
-  def __init__(self, vertices):
-    self._vertices = vertices
+  def __init__(self, points):
     self._area = None
-    self._points = None
+    self._points = points
+    self._points_list = None
     self._normal = None
 
   @property
   def points(self) -> np.ndarray:
-    if self._points is None:
-      self._points = self._vertices
     return self._points
 
+  @property
+  def points_list(self) -> np.ndarray:
+    """
+    Solid surface point coordinates list [x, y, z, x, y, z,...]
+    :return: np.ndarray
+    """
+    if self._points_list is None:
+      s = self.points
+      self._points_list = np.reshape(s, len(s) * 3)
+    return self._points_list
+
   @property
   def area(self):
     """
diff --git a/city_model_structure/attributes/polyhedron.py b/city_model_structure/attributes/polyhedron.py
index 655361b0..d9d6a2bb 100644
--- a/city_model_structure/attributes/polyhedron.py
+++ b/city_model_structure/attributes/polyhedron.py
@@ -9,18 +9,17 @@ import numpy as np
 from trimesh import Trimesh
 from helpers.geometry_helper import GeometryHelper
 from helpers.configuration_helper import ConfigurationHelper
-from city_model_structure.attributes.surface import Surface
+from city_model_structure.attributes.polygon import Polygon
+from helpers.geometry_helper import GeometryHelper as gh
 
 
 class Polyhedron:
-  # todo: modify class to call polygons better than surfaces
   """
   Polyhedron class
   """
 
-  def __init__(self, surfaces):
-    self._surfaces = list(surfaces)
-    self._polygons = [s.polygon for s in surfaces]
+  def __init__(self, polygons):
+    self._polygons = polygons
     self._polyhedron = None
     self._triangulated_polyhedron = None
     self._volume = None
@@ -52,7 +51,7 @@ class Polyhedron:
     """
     if self._vertices is None:
       vertices, self._vertices = [], []
-      _ = [vertices.extend(s.points) for s in self._surfaces]
+      _ = [vertices.extend(s.points) for s in self._polygons]
       for vertex_1 in vertices:
         found = False
         for vertex_2 in self._vertices:
@@ -65,18 +64,14 @@ class Polyhedron:
       self._vertices = np.asarray(self._vertices)
     return self._vertices
 
-  @staticmethod
-  def _point(coordinates):
-    return coordinates[0], coordinates[1], coordinates[2]
-
-  def _triangulate(self, surface):
+  def _triangulate(self, polygon) -> [Polygon]:
     """
     triangulates a polygon following the ear clipping methodology
-    :param surface: surface
+    :param polygon: polygon
     :return: list[triangles]
     """
-    points_list = surface.points_list
-    normal = surface.normal
+    points_list = polygon.points_list
+    normal = polygon.normal
     # are points concave or convex?
     total_points_list, concave_points, convex_points = self._starting_lists(points_list, normal)
 
@@ -87,7 +82,7 @@ class Polyhedron:
         ear = self._triangle(points_list, total_points_list, concave_points[i])
         rest_points = []
         for p in total_points_list:
-          rest_points.append(list(surface.points[p]))
+          rest_points.append(list(polygon.points[p]))
         if self._is_ear(ear, rest_points):
           ears.append(ear)
           point_to_remove = concave_points[i]
@@ -115,8 +110,8 @@ class Polyhedron:
               continue
           break
       if len(total_points_list) <= 3 and len(convex_points) > 0:
-        sys.stderr.write(f'Not able to triangulate surface type {surface.type}\n')
-        return [surface]
+        sys.stderr.write(f'Not able to triangulate polygon\n')
+        return [polygon]
     last_ear = self._triangle(points_list, total_points_list, concave_points[1])
     ears.append(last_ear)
     return ears
@@ -215,16 +210,18 @@ class Polyhedron:
     """
     is_concave = False
     accepted_error = 0.1
-    points = ' '.join(str(e) for e in [*previous_point[:], *point[:], *next_point[:]])
-    triangle = Surface(points, remove_last=False)
+    points = np.append(previous_point, point)
+    points = np.append(points, next_point)
+    points = gh.to_points_matrix(points)
+    triangle = Polygon(points)
     error_sum = 0
     for i in range(0, len(normal)):
-      error_sum += triangle.perimeter_surface.normal[i] - normal[i]
+      error_sum += triangle.normal[i] - normal[i]
     if np.abs(error_sum) < accepted_error:
       is_concave = True
     return is_concave
 
-  def _triangle(self, points_list, total_points_list, point_position):
+  def _triangle(self, points_list, total_points_list, point_position) -> Polygon:
     """
     creates a triangular polygon out of three points
     :param points_list: points_list
@@ -234,10 +231,11 @@ class Polyhedron:
     """
     index = point_position * 3
     previous_point_index, next_point_index = self._enveloping_points_indices(point_position, total_points_list)
-    points = ' '.join(str(e) for e in [*points_list[previous_point_index:previous_point_index + 3],
-                                       *points_list[index:index + 3],
-                                       *points_list[next_point_index:next_point_index + 3]])
-    triangle = Surface(points, remove_last=False)
+    points = points_list[previous_point_index:previous_point_index + 3]
+    points = np.append(points, points_list[index:index + 3])
+    points = np.append(points, points_list[next_point_index:next_point_index + 3])
+    points = gh.to_points_matrix(points)
+    triangle = Polygon(points)
     return triangle
 
   @staticmethod
@@ -288,11 +286,11 @@ class Polyhedron:
   def _is_ear(ear, points) -> bool:
     """
     finds whether a triangle is an ear of the polygon
-    :param ear: surface
+    :param ear: polygon
     :param points: [point]
     :return: boolean
     """
-    area_ear = ear.perimeter_surface.area
+    area_ear = ear.area
     for point in points:
       area_points = 0
       point_is_not_vertex = True
@@ -303,11 +301,16 @@ class Polyhedron:
       if point_is_not_vertex:
         for i in range(0, 3):
           if i != 2:
-            new_points = ' '.join(str(e) for e in [*ear.points[i][:], *ear.points[i + 1][:], *point[:]])
+            new_points = ear.points[i][:]
+            new_points = np.append(new_points, ear.points[i + 1][:])
+            new_points = np.append(new_points, point[:])
           else:
-            new_points = ' '.join(str(e) for e in [*ear.points[i][:], *point[:], *ear.points[0][:]])
-          new_triangle = Surface(new_points, remove_last=False)
-          area_points += new_triangle.perimeter_surface.area
+            new_points = ear.points[i][:]
+            new_points = np.append(new_points, point[:])
+            new_points = np.append(new_points, ear.points[0][:])
+          new_points = gh.to_points_matrix(new_points)
+          new_triangle = Polygon(new_points)
+          area_points += new_triangle.area
       if abs(area_points - area_ear) < 1e-6:
         # point_inside_ear = True
         return False
@@ -324,17 +327,17 @@ class Polyhedron:
     if self._faces is None:
       self._faces = []
 
-      for surface in self._surfaces:
+      for polygon in self._polygons:
 
         face = []
-        points = surface.points
+        points = polygon.points
         if len(points) != 3:
-          sub_surfaces = self._triangulate(surface)
+          sub_polygons = self._triangulate(polygon)
           # todo: I modified this! To be checked @Guille
-          if len(sub_surfaces) >= 1:
-            for sub_surface in sub_surfaces:
+          if len(sub_polygons) >= 1:
+            for sub_polygon in sub_polygons:
               face = []
-              points = sub_surface.points
+              points = sub_polygon.points
               for point in points:
                 face.append(self._position_of(point, face))
               self._faces.append(face)
@@ -371,8 +374,8 @@ class Polyhedron:
     """
     if self._max_z is None:
       self._max_z = ConfigurationHelper().min_coordinate
-      for surface in self._surfaces:
-        for point in surface.points:
+      for polygon in self._polygons:
+        for point in polygon.points:
           if self._max_z < point[2]:
             self._max_z = point[2]
     return self._max_z
@@ -385,8 +388,8 @@ class Polyhedron:
     """
     if self._max_y is None:
       self._max_y = ConfigurationHelper().min_coordinate
-      for surface in self._surfaces:
-        for point in surface.points:
+      for polygon in self._polygons:
+        for point in polygon.points:
           if self._max_y < point[1]:
             self._max_y = point[1]
     return self._max_y
@@ -399,8 +402,8 @@ class Polyhedron:
     """
     if self._max_x is None:
       self._max_x = ConfigurationHelper().min_coordinate
-      for surface in self._surfaces:
-        for point in surface.points:
+      for polygon in self._polygons:
+        for point in polygon.points:
           self._max_x = max(self._max_x, point[0])
     return self._max_x
 
@@ -412,8 +415,8 @@ class Polyhedron:
     """
     if self._min_z is None:
       self._min_z = self.max_z
-      for surface in self._surfaces:
-        for point in surface.points:
+      for polygon in self._polygons:
+        for point in polygon.points:
           if self._min_z > point[2]:
             self._min_z = point[2]
     return self._min_z
@@ -426,8 +429,8 @@ class Polyhedron:
     """
     if self._min_y is None:
       self._min_y = self.max_y
-      for surface in self._surfaces:
-        for point in surface.points:
+      for polygon in self._polygons:
+        for point in polygon.points:
           if self._min_y > point[1]:
             self._min_y = point[1]
     return self._min_y
@@ -440,8 +443,8 @@ class Polyhedron:
     """
     if self._min_x is None:
       self._min_x = self.max_x
-      for surface in self._surfaces:
-        for point in surface.points:
+      for polygon in self._polygons:
+        for point in polygon.points:
           if self._min_x > point[0]:
             self._min_x = point[0]
     return self._min_x
diff --git a/city_model_structure/attributes/surface.py b/city_model_structure/attributes/surface.py
index eab0d10f..b1be28d8 100644
--- a/city_model_structure/attributes/surface.py
+++ b/city_model_structure/attributes/surface.py
@@ -27,6 +27,7 @@ class Surface:
     self._holes_points = None
     self._holes_points_list = None
     self._perimeter_points = None
+    self._perimeter_points_list = None
     self._azimuth = None
     self._inclination = None
     self._area_above_ground = None
@@ -37,9 +38,9 @@ class Surface:
     self._min_z = None
     self._shared_surfaces = []
     self._global_irradiance = dict()
-    self._perimeter_surface = None
-    self._hole_surfaces = None
-    self._solid_surface = None
+    self._perimeter_polygon = None
+    self._hole_polygons = None
+    self._solid_polygons = None
 
   def parent(self, parent, surface_id):
     """
@@ -103,6 +104,37 @@ class Surface:
         self._holes_points.append(hole_points)
     return self._holes_points
 
+  @property
+  def perimeter_points(self) -> np.ndarray:
+    """
+    Matrix of points of the perimeter in the same order as in coordinates [[x, y, z],[x, y, z],...]
+    :return: np.ndarray
+    """
+    if self._perimeter_points is None:
+      if self.holes_points is None:
+        self._perimeter_points = self.points
+      else:
+        _perimeter_coordinates = self._coordinates
+        for hole_points in self.holes_points:
+          _hole = np.append(hole_points, hole_points[0])
+          _closed_hole = ' '.join(str(e) for e in [*_hole[:]])
+          # add a mark 'M' to ensure that the recombination of points does not provoke errors in finding holes
+          _perimeter_coordinates = _perimeter_coordinates.replace(_closed_hole, 'M')
+        _perimeter_coordinates = _perimeter_coordinates.replace('M', '')
+        self._perimeter_points = np.fromstring(_perimeter_coordinates, dtype=float, sep=' ')
+        self._perimeter_points = gh.to_points_matrix(self._perimeter_points)
+        # remove duplicated points
+        pv = np.array([self._perimeter_points[0]])
+        for point in self._perimeter_points:
+          duplicated_point = False
+          for p in pv:
+            if gh().almost_equal(0.0, p, point):
+              duplicated_point = True
+          if not duplicated_point:
+            pv = np.append(pv, [point], axis=0)
+        self._perimeter_points = pv
+    return self._perimeter_points
+
   @property
   def points_list(self) -> np.ndarray:
     """
@@ -128,6 +160,17 @@ class Surface:
         np.add(self._holes_points_list, hole_points_list)
     return self._holes_points_list
 
+  @property
+  def perimeter_points_list(self) -> np.ndarray:
+    """
+    Solid surface point coordinates list [x, y, z, x, y, z,...]
+    :return: np.ndarray
+    """
+    if self._perimeter_points_list is None:
+      s = self.perimeter_points
+      self._perimeter_points_list = np.reshape(s, len(s) * 3)
+    return self._perimeter_points_list
+
   def _min_coord(self, axis):
     if axis == 'x':
       axis = 0
@@ -180,7 +223,7 @@ class Surface:
     :return: float
     """
     if self._area_above_ground is None:
-      self._area_above_ground = self.perimeter_surface.area - self.area_below_ground
+      self._area_above_ground = self.perimeter_polygon.area - self.area_below_ground
     return self._area_above_ground
 
   # todo: to be implemented
@@ -199,7 +242,7 @@ class Surface:
     :return: float
     """
     if self._azimuth is None:
-      normal = self.perimeter_surface.normal
+      normal = self.perimeter_polygon.normal
       self._azimuth = np.arctan2(normal[1], normal[0])
     return self._azimuth
 
@@ -210,7 +253,7 @@ class Surface:
     :return: float
     """
     if self._inclination is None:
-      self._inclination = np.arccos(self.perimeter_surface.normal[2])
+      self._inclination = np.arccos(self.perimeter_polygon.normal[2])
     return self._inclination
 
   @property
@@ -236,7 +279,7 @@ class Surface:
     :param intersection_area:
     :return:
     """
-    percent = intersection_area / self.perimeter_surface.area
+    percent = intersection_area / self.perimeter_polygon.area
     self._shared_surfaces.append((percent, surface))
 
   # todo reimplement
@@ -267,27 +310,27 @@ class Surface:
     self._global_irradiance = value
 
   @property
-  def perimeter_surface(self) -> Polygon:
+  def perimeter_polygon(self) -> Polygon:
     """
     total surface defined by the perimeter, merging solid and holes
     :return: Polygon
     """
-    if self._perimeter_surface is None:
-      self._perimeter_surface = Polygon(self.perimeter_points)
-    return self._perimeter_surface
+    if self._perimeter_polygon is None:
+      self._perimeter_polygon = Polygon(self.perimeter_points)
+    return self._perimeter_polygon
 
   @property
-  def solid_surface(self) -> Polygon:
+  def solid_polygon(self) -> Polygon:
     """
     solid surface
     :return: Polygon
     """
-    if self._solid_surface is None:
-      self._solid_surface = Polygon(self.points)
-    return self._solid_surface
+    if self._solid_polygons is None:
+      self._solid_polygons = Polygon(self.points)
+    return self._solid_polygons
 
   @property
-  def hole_surfaces(self) -> [Polygon]:
+  def hole_polygons(self) -> [Polygon]:
     """
     hole surfaces, a list of hole polygons found in the surface
     :return: None, [] or [Polygon]
@@ -295,42 +338,11 @@ class Surface:
       [] -> no holes in the surface
       [Polygon] -> one or more holes in the surface
     """
-    if self._hole_surfaces is None:
+    if self._hole_polygons is None:
       if self.holes_points is None:
-        self._hole_surfaces = None
+        self._hole_polygons = None
       else:
-        self._hole_surfaces = []
+        self._hole_polygons = []
         for hole_points in self.holes_points:
-          self._hole_surfaces.append(Polygon(hole_points))
-    return self._hole_surfaces
-
-  @property
-  def perimeter_points(self) -> np.ndarray:
-    """
-    Matrix of points of the perimeter in the same order as in coordinates [[x, y, z],[x, y, z],...]
-    :return: np.ndarray
-    """
-    if self._perimeter_points is None:
-      if self.holes_points is None:
-        self._perimeter_points = self.points
-      else:
-        _perimeter_coordinates = self._coordinates
-        for hole_points in self.holes_points:
-          _hole = np.append(hole_points, hole_points[0])
-          _closed_hole = ' '.join(str(e) for e in [*_hole[:]])
-          # add a mark 'M' to ensure that the recombination of points does not provoke errors in finding holes
-          _perimeter_coordinates = _perimeter_coordinates.replace(_closed_hole, 'M')
-        _perimeter_coordinates = _perimeter_coordinates.replace('M', '')
-        self._perimeter_points = np.fromstring(_perimeter_coordinates, dtype=float, sep=' ')
-        self._perimeter_points = gh.to_points_matrix(self._perimeter_points)
-        # remove duplicated points
-        pv = np.array([self._perimeter_points[0]])
-        for point in self._perimeter_points:
-          duplicated_point = False
-          for p in pv:
-            if gh().almost_equal(0.0, p, point):
-              duplicated_point = True
-          if not duplicated_point:
-            pv = np.append(pv, [point], axis=0)
-        self._perimeter_points = pv
-    return self._perimeter_points
+          self._hole_polygons.append(Polygon(hole_points))
+    return self._hole_polygons
diff --git a/city_model_structure/attributes/thermal_boundary.py b/city_model_structure/attributes/thermal_boundary.py
index c4eb90e8..1316d24e 100644
--- a/city_model_structure/attributes/thermal_boundary.py
+++ b/city_model_structure/attributes/thermal_boundary.py
@@ -19,7 +19,7 @@ class ThermalBoundary:
     self._surface = surface
     self._delimits = delimits
     # ToDo: up to at least LOD2 will be just one thermal opening per Thermal boundary, review for LOD3 and LOD4
-    self._thermal_openings = [ThermalOpening]
+    self._thermal_openings = [ThermalOpening()]
     self._layers = None
     self._outside_solar_absorptance = None
     self._outside_thermal_absorptance = None
@@ -83,7 +83,7 @@ class ThermalBoundary:
     Thermal boundary area in square meters
     :return: float
     """
-    return self._surface.area
+    return self._surface.solid_polygon.area
 
   @property
   def area_above_ground(self):
diff --git a/city_model_structure/attributes/thermal_zone.py b/city_model_structure/attributes/thermal_zone.py
index f686f291..a1345312 100644
--- a/city_model_structure/attributes/thermal_zone.py
+++ b/city_model_structure/attributes/thermal_zone.py
@@ -57,7 +57,7 @@ class ThermalZone:
       self._floor_area = 0
       for s in self._surfaces:
         if s.type == 'Ground':
-          self._floor_area += s.area
+          self._floor_area += s.perimeter_polygon.area
     return self._floor_area
 
   @property
diff --git a/city_model_structure/city_object.py b/city_model_structure/city_object.py
index 2810b954..d9f6f488 100644
--- a/city_model_structure/city_object.py
+++ b/city_model_structure/city_object.py
@@ -19,7 +19,8 @@ class CityObject:
     self._name = name
     self._lod = lod
     self._surfaces = surfaces
-    self._polyhedron = None
+    self._detailed_polyhedron = None
+    self._simplified_polyhedron = None
     self._geometry = GeometryHelper()
 
   @property
@@ -37,17 +38,36 @@ class CityObject:
     City object volume in cubic meters
     :return: float
     """
-    return self.polyhedron.volume
+    return self.detailed_polyhedron.volume
 
   @property
-  def polyhedron(self):
+  def detailed_polyhedron(self):
     """
-    City object polyhedron
+    City object polyhedron including details such as holes
     :return: Polyhedron
     """
-    if self._polyhedron is None:
-      self._polyhedron = Polyhedron(self.surfaces)
-    return self._polyhedron
+    if self._detailed_polyhedron is None:
+      polygons = []
+      for surface in self.surfaces:
+        polygons.append(surface.solid_polygon)
+        if surface.hole_polygons is not None:
+          for hole_polygon in surface.hole_polygons:
+            polygons.append(hole_polygon)
+      self._detailed_polyhedron = Polyhedron(polygons)
+    return self._detailed_polyhedron
+
+  @property
+  def simplified_polyhedron(self):
+    """
+    City object polyhedron, just the simple lod2 representation
+    :return: Polyhedron
+    """
+    if self._simplified_polyhedron is None:
+      polygons = []
+      for surface in self.surfaces:
+        polygons.append(surface.perimeter_polygon)
+      self._simplified_polyhedron = Polyhedron(polygons)
+    return self._simplified_polyhedron
 
   @property
   def surfaces(self) -> List[Surface]:
@@ -74,32 +94,7 @@ class CityObject:
     City object location
     :return: [x,y,z]
     """
-    if self._polyhedron is None:
-      self._polyhedron = Polyhedron(self.surfaces)
-    return self._polyhedron.center
-
-  def stl_export(self, path):
-    """
-    Export the city object to stl file (city_object_name.stl) to the given path
-    :param path: str
-    :return: None
-    """
-    # todo: this is a method just for debugging, it will be soon removed
-    if self._polyhedron is None:
-      self._polyhedron = Polyhedron(self.surfaces)
-    full_path = (Path(path) / (self._name + '.stl')).resolve()
-    self._polyhedron.stl_export(full_path)
-
-  def obj_export(self, path):
-    if self._polyhedron is None:
-      self._polyhedron = Polyhedron(self.surfaces)
-    full_path = (Path(path) / (self._name + '.obj')).resolve()
-    self._polyhedron.obj_export(full_path)
-
-  def show(self):
-    if self._polyhedron is None:
-      self._polyhedron = Polyhedron(self.surfaces)
-    self._polyhedron.show()
+    return self.simplified_polyhedron.center
 
   @property
   def max_height(self):
@@ -107,6 +102,4 @@ class CityObject:
     City object maximal height in meters
     :return: float
     """
-    if self._polyhedron is None:
-      self._polyhedron = Polyhedron(self.surfaces)
-    return self._polyhedron.max_z
+    return self.simplified_polyhedron.max_z
diff --git a/imports/geometry_feeders/city_gml.py b/imports/geometry_feeders/city_gml.py
index 2e7561a8..9cff2ac7 100644
--- a/imports/geometry_feeders/city_gml.py
+++ b/imports/geometry_feeders/city_gml.py
@@ -120,7 +120,7 @@ class CityGml:
     terrains = []
     for curve in curves:
       curve_points = np.fromstring(curve, dtype=float, sep=' ')
-      curve_points = self._geometry.to_points_matrix(curve_points, True)
+      curve_points = self._geometry.to_points_matrix(curve_points)
       terrains.append(curve_points)
     return terrains
 
@@ -136,7 +136,7 @@ class CityGml:
 
   @staticmethod
   def _lod1_multi_surface(o):
-    surfaces = [Surface(CityGml._remove_last_point((s['Polygon']['exterior']['LinearRing']['posList']))
+    surfaces = [Surface(CityGml._remove_last_point(s['Polygon']['exterior']['LinearRing']['posList']))
                 for s in o['Building']['lod1MultiSurface']['MultiSurface']['surfaceMember']]
     return surfaces
 
@@ -178,4 +178,4 @@ class CityGml:
   def _remove_last_point(points):
     array = points.split(' ')
     res = " "
-    return res.join(array[0:len(array) -3])
+    return res.join(array[0:len(array) - 3])
diff --git a/tests/test_geometry_factory.py b/tests/test_geometry_factory.py
index 935e6a5e..97e2901e 100644
--- a/tests/test_geometry_factory.py
+++ b/tests/test_geometry_factory.py
@@ -85,7 +85,6 @@ class TestGeometryFactory(TestCase):
         print('volume', building.name, building.volume)
         if str(building.volume) == 'inf':
           counter += 1
-        building.stl_export(self._output_path)
     print('total number of buildings with volume inf', counter)
 
   def test_citygml_buildings(self):
@@ -123,7 +122,6 @@ class TestGeometryFactory(TestCase):
     :return: None
     """
     city = self._get_citygml()
-    print(city)
     for building in city.buildings:
       for surface in building.surfaces:
         self.assertIsNotNone(surface.name, 'surface name is none')
@@ -139,8 +137,6 @@ class TestGeometryFactory(TestCase):
         self.assertIsNotNone(surface.min_x, 'surface min_x is none')
         self.assertIsNotNone(surface.min_y, 'surface min_y is none')
         self.assertIsNotNone(surface.min_z, 'surface min_z is none')
-        print('points', surface.points)
-        print('coordinates', surface._coordinates)
 
   def test_citygml_thermal_zone(self):
     """
@@ -257,10 +253,10 @@ class TestGeometryFactory(TestCase):
     print(surface.holes_points)
     print('perimeter:', surface.perimeter_points)
     for i in range(0, len(holes_coordinates)):
-      print(surface.hole_surfaces[i].area)
-    print('perimeter:', surface.perimeter_surface.area)
-    print('solid:', surface.solid_surface.area)
+      print(surface.hole_polygons[i].area)
+    print('perimeter:', surface.perimeter_polygon.area)
+    print('solid:', surface.solid_polygon.area)
     for i in range(0, len(holes_coordinates)):
-      print(surface.hole_surfaces[i].normal)
-    print('perimeter:', surface.perimeter_surface.normal)
-    print('solid:', surface.solid_surface.normal)
+      print(surface.hole_polygons[i].normal)
+    print('perimeter:', surface.perimeter_polygon.normal)
+    print('solid:', surface.solid_polygon.normal)
diff --git a/tests_data/kelowna_test_case.pickle b/tests_data/kelowna_test_case.pickle
index 4897d569..af0a71b1 100644
Binary files a/tests_data/kelowna_test_case.pickle and b/tests_data/kelowna_test_case.pickle differ