diff --git a/helpers/constants.py b/helpers/constants.py
index 49ec5aef..31597435 100644
--- a/helpers/constants.py
+++ b/helpers/constants.py
@@ -1,8 +1,51 @@
+# universal constants
 KELVIN = 273.15
+
+# time
 MINUTE = 'minute'
 HOUR = 'hour'
 DAY = 'day'
 WEEK = 'week'
 MONTH = 'month'
 YEAR = 'year'
+
+# todo: modify code to use global constants instead of hard-coded values
+# surface types
+WALL = 'Wall'
+GROUND_WALL = 'Ground wall'
+GROUND = 'Ground'
+ATTIC_FLOOR = 'Attic floor'
+ROOF = 'Roof'
+INTERIOR_SLAB = 'Interior slab'
+INTERIOR_WALL = 'Interior wall'
+WINDOW = 'Window'
+DOOR = 'Door'
+SKYLIGHT = 'Skylight'
+
+# todo: homogenize function and usage!!
+# function
+RESIDENTIAL = 'residential'
+SFH = 'single family house'
+MFH = 'multifamily house'
+HOTEL = 'hotel'
+HOSPITAL = 'hospital'
+OUTPATIENT = 'outpatient'
+COMMERCIAL = 'commercial'
+STRIP_MALL = 'strip mall'
+WAREHOUSE = 'warehouse'
+PRIMARY_SCHOOL = 'primary school'
+SECONDARY_SCHOOL = 'secondary school'
+OFFICE = 'office'
+LARGE_OFFICE = 'large office'
+
+# usage
+INDUSTRY = 'industry'
+OFFICE_ADMINISTRATION = 'office and administration'
+HEALTH_CARE = 'health care'
+RETAIL = 'retail'
+HALL = 'hall'
+RESTAURANT = 'restaurant'
+EDUCATION = 'education'
+
+# general project-related
 ROUGHNESS = "MediumRough"
diff --git a/helpers/enrich_city.py b/helpers/enrich_city.py
new file mode 100644
index 00000000..fc4cc337
--- /dev/null
+++ b/helpers/enrich_city.py
@@ -0,0 +1,71 @@
+"""
+Enrich city
+SPDX - License - Identifier: LGPL - 3.0 - or -later
+Copyright © 2020 Project Author Pilar Monsalvete Alvarez de Uribarri pilar.monsalvete@concordia.ca
+"""
+
+from imports.construction_factory import ConstructionFactory
+from imports.usage_factory import UsageFactory
+from imports.schedules_factory import SchedulesFactory
+
+
+class EnrichCity:
+  def __init__(self, city):
+    self._city = city
+    self._enriched_city = None
+    self._errors = []
+
+  @property
+  def errors(self):
+    return self._errors
+
+  def enriched_city(self, construction_format=None, usage_format=None, schedules_format=None):
+    if self._enriched_city is None:
+      self._errors = []
+
+      print('original:', len(self._city.buildings))
+      if construction_format is not None:
+        ConstructionFactory(construction_format, self._city).enrich()
+        for building in self._city.buildings:
+          # infiltration_rate_system_off is a mandatory parameter.
+          # If it is not returned, extract the building from the calculation list
+          if building.thermal_zones[0].infiltration_rate_system_off is None:
+            self._city.remove_city_object(building)
+        if self._city.buildings is None:
+          self._errors.append('no archetype found per construction')
+          self._enriched_city = self._city
+          return self._enriched_city
+        print('enriched with construction:', len(self._city.buildings))
+
+      if usage_format is not None:
+        UsageFactory(usage_format, self._city).enrich()
+        for building in self._city.buildings:
+          # At least one thermal zone must be created.
+          # If it is not created, extract the building from the calculation list
+          if len(building.usage_zones) <= 0:
+            self._city.remove_city_object(building)
+        if self._city.buildings is None:
+          self._errors.append('no archetype found per usage')
+          self._enriched_city = self._city
+          return self._enriched_city
+        print('enriched with usage:', len(self._city.buildings))
+
+      if schedules_format is not None:
+        SchedulesFactory(schedules_format, self._city).enrich()
+        for building in self._city.buildings:
+          counter_schedules = 0
+          for usage_zone in building.usage_zones:
+            # At least one schedule must be created at each thermal zone.
+            # If it is not created, extract the building from the calculation list
+            if len(usage_zone.schedules) > 0:
+              counter_schedules += 1
+          if counter_schedules < len(building.usage_zones):
+            self._city.remove_city_object(building)
+        if self._city.buildings is None:
+          self._errors.append('no archetype found per usage')
+          self._enriched_city = self._city
+          return self._enriched_city
+        print('enriched with occupancy:', len(self._city.buildings))
+
+    self._enriched_city = self._city
+    return self._enriched_city
diff --git a/imports/construction/helpers/construction_helper.py b/imports/construction/helpers/construction_helper.py
index 7257da0d..0a3c1f50 100644
--- a/imports/construction/helpers/construction_helper.py
+++ b/imports/construction/helpers/construction_helper.py
@@ -4,24 +4,25 @@ SPDX - License - Identifier: LGPL - 3.0 - or -later
 Copyright © 2020 Project Author Pilar Monsalvete Alvarez de Uribarri pilar.monsalvete@concordia.ca
 """
 import sys
+from helpers import constants as cte
 
 
 class ConstructionHelper:
   # NREL
   function_to_nrel = {
-    'residential': 'residential',
-    'single family house': 'single family house',
-    'multifamily house': 'multifamily house',
-    'hotel': 'hotel',
-    'hospital': 'hospital',
-    'outpatient': 'outpatient',
-    'commercial': 'commercial',
-    'strip mall': 'strip mall',
-    'warehouse': 'warehouse',
-    'primary school': 'primary school',
-    'secondary school': 'secondary school',
-    'office': 'office',
-    'large office': 'large office'
+    cte.RESIDENTIAL: 'residential',
+    cte.SFH: 'single family house',
+    cte.MFH: 'multifamily house',
+    cte.HOTEL: 'hotel',
+    cte.HOSPITAL: 'hospital',
+    cte.OUTPATIENT: 'outpatient',
+    cte.COMMERCIAL: 'commercial',
+    cte.STRIP_MALL: 'strip mall',
+    cte.WAREHOUSE: 'warehouse',
+    cte.PRIMARY_SCHOOL: 'primary school',
+    cte.SECONDARY_SCHOOL: 'secondary school',
+    cte.OFFICE: 'office',
+    cte.LARGE_OFFICE: 'large office'
   }
   nrel_function_default_value = 'residential'
   nrel_standards = {
@@ -46,42 +47,42 @@ class ConstructionHelper:
     'Duluth': 'ASHRAE_2004:7A',
     'Fairbanks': 'ASHRAE_2004:8A'
   }
-  nrel_window_types = ['window', 'door', 'skylight']
+  nrel_window_types = [cte.WINDOW, cte.DOOR, cte.SKYLIGHT]
   nrel_construction_types = {
-    'Wall': 'exterior wall',
-    'Interior wall': 'interior wall',
-    'Ground wall': 'ground wall',
-    'Ground': 'exterior slab',
-    'Attic floor': 'attic floor',
-    'Interior slab': 'interior slab',
-    'Roof': 'roof'
+    cte.WALL: 'exterior wall',
+    cte.INTERIOR_WALL: 'interior wall',
+    cte.GROUND_WALL: 'ground wall',
+    cte.GROUND: 'exterior slab',
+    cte.ATTIC_FLOOR: 'attic floor',
+    cte.INTERIOR_SLAB: 'interior slab',
+    cte.ROOF: 'roof'
   }
 
   # NRCAN
   function_to_nrcan = {
-    'residential': 'residential',
-    'single family house': 'single family house',
-    'multifamily house': 'multifamily house',
-    'hotel': 'hotel',
-    'hospital': 'hospital',
-    'outpatient': 'outpatient',
-    'commercial': 'commercial',
-    'strip mall': 'strip mall',
-    'warehouse': 'warehouse',
-    'primary school': 'primary school',
-    'secondary school': 'secondary school',
-    'office': 'office',
-    'large office': 'large office'
+    cte.RESIDENTIAL: 'residential',
+    cte.SFH: 'single family house',
+    cte.MFH: 'multifamily house',
+    cte.HOTEL: 'hotel',
+    cte.HOSPITAL: 'hospital',
+    cte.OUTPATIENT: 'outpatient',
+    cte.COMMERCIAL: 'commercial',
+    cte.STRIP_MALL: 'strip mall',
+    cte.WAREHOUSE: 'warehouse',
+    cte.PRIMARY_SCHOOL: 'primary school',
+    cte.SECONDARY_SCHOOL: 'secondary school',
+    cte.OFFICE: 'office',
+    cte.LARGE_OFFICE: 'large office'
   }
   nrcan_function_default_value = 'residential'
-  nrcan_window_types = ['window']
+  nrcan_window_types = [cte.WINDOW]
   nrcan_construction_types = {
-    'Wall': 'wall',
-    'Ground wall': 'basement_wall',
-    'Ground': 'floor',
-    'Attic floor': 'attic floor',
-    'Interior slab': 'interior slab',
-    'Roof': 'roof'
+    cte.WALL: 'exterior wall',
+    cte.GROUND_WALL: 'ground wall',
+    cte.GROUND: 'exterior slab',
+    cte.ATTIC_FLOOR: 'attic floor',
+    cte.INTERIOR_SLAB: 'interior slab',
+    cte.ROOF: 'roof'
   }
 
   @staticmethod
diff --git a/imports/geometry/helpers/geometry_helper.py b/imports/geometry/helpers/geometry_helper.py
index e80f9663..384897d6 100644
--- a/imports/geometry/helpers/geometry_helper.py
+++ b/imports/geometry/helpers/geometry_helper.py
@@ -4,6 +4,8 @@ SPDX - License - Identifier: LGPL - 3.0 - or -later
 Copyright © 2020 Project Author Pilar Monsalvete Alvarez de Uribarri pilar.monsalvete@concordia.ca
 """
 
+import helpers.constants as cte
+
 
 class GeometryHelper:
   # function
@@ -230,30 +232,30 @@ class GeometryHelper:
     'Z9': 'na'
   }
   hft_to_function = {
-    'residential': 'residential',
-    'single family house': 'single family house',
-    'multifamily house': 'multifamily house',
-    'hotel': 'hotel',
-    'hospital': 'hospital',
-    'outpatient': 'outpatient',
-    'commercial': 'commercial',
-    'strip mall': 'strip mall',
-    'warehouse': 'warehouse',
-    'primary school': 'primary school',
-    'secondary school': 'secondary school',
-    'office': 'office',
-    'large office': 'large office'
+    'residential': cte.RESIDENTIAL,
+    'single family house': cte.SFH,
+    'multifamily house': cte.MFH,
+    'hotel': cte.HOTEL,
+    'hospital': cte.HOSPITAL,
+    'outpatient': cte.OUTPATIENT,
+    'commercial': cte.COMMERCIAL,
+    'strip mall': cte.STRIP_MALL,
+    'warehouse': cte.WAREHOUSE,
+    'primary school': cte.PRIMARY_SCHOOL,
+    'secondary school': cte.SECONDARY_SCHOOL,
+    'office': cte.OFFICE,
+    'large office': cte.LARGE_OFFICE
   }
 
   # usage
   function_to_usage = {
     'full service restaurant': 'restaurant',
-    'highrise apartment': 'residential',
+    'highrise apartment': cte.RESIDENTIAL,
     'hospital': 'health care',
     'large hotel': 'hotel',
     'large office': 'office and administration',
     'medium office': 'office and administration',
-    'midrise apartment': 'residential',
+    'midrise apartment': cte.RESIDENTIAL,
     'outpatient healthcare': 'health care',
     'primary school': 'education',
     'quick service restaurant': 'restaurant',
@@ -264,7 +266,7 @@ class GeometryHelper:
     'strip mall': 'hall',
     'supermarket': 'retail',
     'warehouse': 'industry',
-    'residential': 'residential'
+    'residential': cte.RESIDENTIAL
   }
 
   @staticmethod
diff --git a/imports/schedules/helpers/schedules_helper.py b/imports/schedules/helpers/schedules_helper.py
index 772ffb54..ed5524de 100644
--- a/imports/schedules/helpers/schedules_helper.py
+++ b/imports/schedules/helpers/schedules_helper.py
@@ -5,19 +5,20 @@ Copyright © 2020 Project Author Guille Gutierrez guillermo.gutierrezmorote@conc
 contributors Pilar Monsalvete Alvarez de Uribarri pilar.monsalvete@concordia.ca
 """
 import sys
+import helpers.constants as cte
 
 
 class SchedulesHelper:
   usage_to_comnet = {
-    'residential': 'C-12 Residential',
-    'industry': 'C-10 Warehouse',
-    'office and administration': 'C-5 Office',
-    'hotel': 'C-3 Hotel',
-    'health care': 'C-2 Health',
-    'retail': 'C-8 Retail',
-    'hall': 'C-8 Retail',
-    'restaurant': 'C-7 Restaurant',
-    'education': 'C-9 School'
+    cte.RESIDENTIAL: 'C-12 Residential',
+    cte.INDUSTRY: 'C-10 Warehouse',
+    cte.OFFICE_ADMINISTRATION: 'C-5 Office',
+    cte.HOTEL: 'C-3 Hotel',
+    cte.HEALTH_CARE: 'C-2 Health',
+    cte.RETAIL: 'C-8 Retail',
+    cte.HALL: 'C-8 Retail',
+    cte.RESTAURANT: 'C-7 Restaurant',
+    cte.EDUCATION: 'C-9 School'
   }
   comnet_default_value = 'C-12 Residential'
 
diff --git a/imports/usage/helpers/usage_helper.py b/imports/usage/helpers/usage_helper.py
index e1f27e3a..1657d128 100644
--- a/imports/usage/helpers/usage_helper.py
+++ b/imports/usage/helpers/usage_helper.py
@@ -4,19 +4,20 @@ SPDX - License - Identifier: LGPL - 3.0 - or -later
 Copyright © 2020 Project Author Pilar Monsalvete Alvarez de Uribarri pilar.monsalvete@concordia.ca
 """
 import sys
+import helpers.constants as cte
 
 
 class UsageHelper:
   usage_to_hft = {
-    'residential': 'residential',
-    'industry': 'industry',
-    'office and administration': 'office and administration',
-    'hotel': 'hotel',
-    'health care': 'health care',
-    'retail': 'retail',
-    'hall': 'hall',
-    'restaurant': 'restaurant',
-    'education': 'education'
+    cte.RESIDENTIAL: 'residential',
+    cte.INDUSTRY: 'industry',
+    cte.OFFICE_ADMINISTRATION: 'office and administration',
+    cte.HOTEL: 'hotel',
+    cte.HEALTH_CARE: 'health care',
+    cte.RETAIL: 'retail',
+    cte.HALL: 'hall',
+    cte.RESTAURANT: 'restaurant',
+    cte.EDUCATION: 'education'
   }
   hft_default_value = 'residential'
 
diff --git a/non_functional_tests/test_geometry_factory.py b/non_functional_tests/test_geometry_factory.py
index 35f9c1ae..62e30a64 100644
--- a/non_functional_tests/test_geometry_factory.py
+++ b/non_functional_tests/test_geometry_factory.py
@@ -7,8 +7,6 @@ from pathlib import Path
 from unittest import TestCase
 from imports.geometry_factory import GeometryFactory
 from imports.geometry.helpers.geometry_helper import GeometryHelper
-from city_model_structure.city import City
-from exports.exports_factory import ExportsFactory
 
 
 class TestGeometryFactory(TestCase):