diff --git a/lca_carbon_workflow.py b/lca_carbon_workflow.py
index f350a8c..6d45e7e 100644
--- a/lca_carbon_workflow.py
+++ b/lca_carbon_workflow.py
@@ -60,7 +60,6 @@ class LCACarbonWorkflow:
   def calculate_building_component_emission(self, building):
     surface_envelope_emission = []
     surface_opening_emission = []
-    period_of_construction = self.nrcan_catalogs.year_to_period_of_construction(building.year_of_construction)
     opaque_surface_code = self.nrcan_catalogs.find_opaque_surface(
       self.nrcan_catalogs.hub_to_nrcan_function(building.function),
       self.nrcan_catalogs.year_to_period_of_construction(