diff --git a/demandlib/bdew.py b/demandlib/bdew.py
index 3a0d4b5..38c5aa6 100644
--- a/demandlib/bdew.py
+++ b/demandlib/bdew.py
@@ -342,3 +342,47 @@ def get_normalized_bdew_profile(self):
         heat_profile_normalized = (kw * h * f * sf)
 
         return heat_profile_normalized
+
+    def get_cop(self, heatpump_type = "Air", water_temp = 60):
+        """ Calculation of the coefficient of performance depending
+        on the outside temperature
+        
+        Parameters
+        ----------
+        heatpump_type: string
+            defines the technology used. Ground is more efficient than Air.
+        water_temp: int
+            temperature needed for the heating system
+            
+        References
+        ----------
+        ..  [1]: 'https://www.researchgate.net/publication/255759857_A_review_of_domestic_heat_pumps'
+            Research paper about domestic heatpumps, containing the formulas used
+        """
+
+        cop_lst = []
+        
+        if heatpump_type == "Air":
+            for tmp in self.temperature:
+                cop = (6.81 - 0.121 * (water_temp - tmp)
+                       + 0.00063 * (water_temp - tmp)**2)
+                cop_lst.append(cop)
+        
+        elif heatpump_type == "Ground":
+            for tmp in self.temperature:
+                cop = (8.77 - 0.15 * (water_temp - tmp)
+                       + 0.000734 * (water_temp - tmp)**2)
+                cop_lst.append(cop)
+        
+        else:
+            # TODO Raise Error
+            print("Heatpump type is not defined")
+            return -9999
+
+        self.cop = pd.DataFrame({"cop" : cop_lst})
+        self.cop.set_index(self.df.index, inplace = True)
+
+                
+        return self.cop
+    
+    
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