diff --git a/costs/__init__.py b/costs/__init__.py
index 9e6f8b2..091f134 100644
--- a/costs/__init__.py
+++ b/costs/__init__.py
@@ -22,19 +22,7 @@ BASEMENT_HEATED_CASE = 1
 CLIMATE_REFERENCE_CITY = 'Montreal'
 WEATHER_FILE = 'CAN_PQ_Montreal.Intl.AP.716270_CWEC.epw'
 WEATHER_FORMAT = 'epw'
-CURRENT_STATUS = 0
 
-# constants
-
-SKIN_RETROFIT = 1
-SYSTEM_RETROFIT_AND_PV = 2
-SKIN_RETROFIT_AND_SYSTEM_RETROFIT_AND_PV = 3
-RETROFITTING_SCENARIOS = [
-  CURRENT_STATUS,
-  SKIN_RETROFIT,
-  SYSTEM_RETROFIT_AND_PV,
-  SKIN_RETROFIT_AND_SYSTEM_RETROFIT_AND_PV
-]
 tmp_folder = Path('./tmp').resolve()
 out_path = Path('./outputs').resolve()
 files = glob.glob(f'{out_path}/*')
diff --git a/costs/capital_costs.py b/costs/capital_costs.py
index ce7835a..e26c997 100644
--- a/costs/capital_costs.py
+++ b/costs/capital_costs.py
@@ -7,8 +7,8 @@ import pandas as pd
 import numpy_financial as npf
 from hub.city_model_structure.building import Building
 import hub.helpers.constants as cte
-from configuration import Configuration
-from costs import SKIN_RETROFIT, SKIN_RETROFIT_AND_SYSTEM_RETROFIT_AND_PV, SYSTEM_RETROFIT_AND_PV
+from costs.configuration import Configuration
+from costs.constants import SKIN_RETROFIT, SKIN_RETROFIT_AND_SYSTEM_RETROFIT_AND_PV, SYSTEM_RETROFIT_AND_PV
 from costs.cost_base import CostBase
 
 
diff --git a/costs/configuration.py b/costs/configuration.py
index b7929d7..907efdf 100644
--- a/costs/configuration.py
+++ b/costs/configuration.py
@@ -1,7 +1,7 @@
 """
 Configuration module
 """
-from hub.catalog_factories.costs_catalog_factory import CostCatalogFactory
+from hub.catalog_factories.costs_catalog_factory import CostsCatalogFactory
 from hub.catalog_factories.catalog import Catalog
 
 
@@ -36,7 +36,7 @@ class Configuration:
     self._discount_rate = discount_rate
     self._retrofitting_year_construction = retrofitting_year_construction
     self._factories_handler = factories_handler
-    self._cost_catalog = CostCatalogFactory(factories_handler).catalog
+    self._cost_catalog = CostsCatalogFactory(factories_handler).catalog
     self._retrofit_scenario = retrofit_scenario
     self._fuel_type = fuel_type
 
diff --git a/costs/constants.py b/costs/constants.py
new file mode 100644
index 0000000..5407f14
--- /dev/null
+++ b/costs/constants.py
@@ -0,0 +1,11 @@
+# constants
+CURRENT_STATUS = 0
+SKIN_RETROFIT = 1
+SYSTEM_RETROFIT_AND_PV = 2
+SKIN_RETROFIT_AND_SYSTEM_RETROFIT_AND_PV = 3
+RETROFITTING_SCENARIOS = [
+  CURRENT_STATUS,
+  SKIN_RETROFIT,
+  SYSTEM_RETROFIT_AND_PV,
+  SKIN_RETROFIT_AND_SYSTEM_RETROFIT_AND_PV
+]
\ No newline at end of file
diff --git a/costs/cost.py b/costs/cost.py
index 94a02ef..48e11e9 100644
--- a/costs/cost.py
+++ b/costs/cost.py
@@ -5,9 +5,9 @@ import pandas as pd
 import numpy_financial as npf
 from hub.city_model_structure.building import Building
 
-from configuration import Configuration
+from costs.configuration import Configuration
 from costs import CapitalCosts, EndOfLifeCosts, TotalMaintenanceCosts, TotalOperationalCosts, TotalOperationalIncomes
-from costs import CURRENT_STATUS
+from costs.constants import CURRENT_STATUS
 
 
 class Cost:
diff --git a/costs/cost_base.py b/costs/cost_base.py
index 0ff5102..5408a78 100644
--- a/costs/cost_base.py
+++ b/costs/cost_base.py
@@ -4,7 +4,7 @@ Cost base module
 
 from hub.city_model_structure.building import Building
 
-from configuration import Configuration
+from costs.configuration import Configuration
 
 
 class CostBase:
diff --git a/costs/end_of_life_costs.py b/costs/end_of_life_costs.py
index 7f7cf41..4723300 100644
--- a/costs/end_of_life_costs.py
+++ b/costs/end_of_life_costs.py
@@ -5,7 +5,7 @@ import math
 import pandas as pd
 from hub.city_model_structure.building import Building
 
-from configuration import Configuration
+from costs.configuration import Configuration
 from costs.cost_base import CostBase
 
 
diff --git a/costs/total_maintenance_costs.py b/costs/total_maintenance_costs.py
index 8dce3b8..c28b3df 100644
--- a/costs/total_maintenance_costs.py
+++ b/costs/total_maintenance_costs.py
@@ -6,7 +6,7 @@ import pandas as pd
 from hub.city_model_structure.building import Building
 import hub.helpers.constants as cte
 
-from configuration import Configuration
+from costs.configuration import Configuration
 from costs.cost_base import CostBase
 
 
diff --git a/costs/total_operational_costs.py b/costs/total_operational_costs.py
index a6513e5..ec44735 100644
--- a/costs/total_operational_costs.py
+++ b/costs/total_operational_costs.py
@@ -7,7 +7,7 @@ import pandas as pd
 from hub.city_model_structure.building import Building
 import hub.helpers.constants as cte
 
-from configuration import Configuration
+from costs.configuration import Configuration
 from costs.cost_base import CostBase
 
 
diff --git a/costs/total_operational_incomes.py b/costs/total_operational_incomes.py
index c8af92c..512db8c 100644
--- a/costs/total_operational_incomes.py
+++ b/costs/total_operational_incomes.py
@@ -6,7 +6,7 @@ import pandas as pd
 from hub.city_model_structure.building import Building
 import hub.helpers.constants as cte
 
-from configuration import Configuration
+from costs.configuration import Configuration
 from costs.cost_base import CostBase
 
 
diff --git a/requirements.txt b/requirements.txt
index bc8992f..add886c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,3 @@
 numpy_financial
-cerc_hub
\ No newline at end of file
+cerc_hub
+pandas
\ No newline at end of file