diff --git a/VECTO3GUI2020/Helper/Converter/LabledTextBoxConverter.cs b/VECTO3GUI2020/Helper/Converter/LabledTextBoxConverter.cs
index 5fe323ec869c2b0c5a62a3b074380494d7ae7619..8858cb9b7e4e06f0267135809fddeffcd0accd64 100644
--- a/VECTO3GUI2020/Helper/Converter/LabledTextBoxConverter.cs
+++ b/VECTO3GUI2020/Helper/Converter/LabledTextBoxConverter.cs
@@ -120,7 +120,7 @@ namespace VECTO3GUI2020.Helper.Converter
 
 		private void GetConversionFactor(ref double factor, string convertId)
 		{
-			switch (convertId.ToLower())
+			switch (convertId.ToLowerInvariant())
 			{
 				case "asrpm":
 					factor = ToRpm;
@@ -133,7 +133,7 @@ namespace VECTO3GUI2020.Helper.Converter
 
 		private void GetDecimals(string arg, ref int? decimals)
 		{
-			switch (arg.ToLower())
+			switch (arg.ToLowerInvariant())
 			{
 				case "int":
 					decimals = 0;
diff --git a/VECTOAux/VectoAuxiliariesTests/UnitTests/FilePathUtilityTests.vb b/VECTOAux/VectoAuxiliariesTests/UnitTests/FilePathUtilityTests.vb
index 466a39eae461196032bb9ae002048616712cb4b8..7466fe2537bc84543f34375285ed72ddcfbb6104 100644
--- a/VECTOAux/VectoAuxiliariesTests/UnitTests/FilePathUtilityTests.vb
+++ b/VECTOAux/VectoAuxiliariesTests/UnitTests/FilePathUtilityTests.vb
@@ -22,7 +22,7 @@ Public Sub GetPathOnly()
 
   Dim actual  As String = FilePathUtils.filePathOnly( GOODFILEPATH_WithExt)
 
-  Assert.AreEqual( expected.ToLower(), actual.ToLower())
+  Assert.AreEqual( expected.ToLowerInvariant(), actual.ToLowerInvariant())
     
 End Sub
 
@@ -33,7 +33,7 @@ Public Sub GetExtOnly()
 
   Dim actual  As String = FilePathUtils.fileExtentionOnly( GOODFILEPATH_WithExt)
 
-  Assert.AreEqual( expected.ToLower(), actual.ToLower())
+  Assert.AreEqual( expected.ToLowerInvariant(), actual.ToLowerInvariant())
 
 End Sub
 
@@ -45,7 +45,7 @@ Public Sub NoFileNameExpectOne()
 
   Dim actual  As String = FilePathUtils.fileNameOnly( noFileFILEPATH, True)
 
-  Assert.AreEqual( expected.ToLower(), actual.ToLower())
+  Assert.AreEqual( expected.ToLowerInvariant(), actual.ToLowerInvariant())
 
 
 End Sub
diff --git a/VectoCore/VectoCore/Models/Declaration/DeclarationData.cs b/VectoCore/VectoCore/Models/Declaration/DeclarationData.cs
index 3ad7187ead1af3f575eb9ead0c768ecc0fe665d7..44c841cf67bd558258e9b834d8d9db6a4db179bb 100644
--- a/VectoCore/VectoCore/Models/Declaration/DeclarationData.cs
+++ b/VectoCore/VectoCore/Models/Declaration/DeclarationData.cs
@@ -153,11 +153,11 @@ namespace TUGraz.VectoCore.Models.Declaration
 		/// </summary>
 		public static Kilogram GetPayloadForGrossVehicleWeight(Kilogram grossVehicleWeight, string equationName)
 		{
-			if (equationName.ToLower().StartsWith("pc10")) {
+			if (equationName.ToLowerInvariant().StartsWith("pc10")) {
 				return Payloads.Lookup10Percent(grossVehicleWeight);
 			}
 
-			if (equationName.ToLower().StartsWith("pc75")) {
+			if (equationName.ToLowerInvariant().StartsWith("pc75")) {
 				return Payloads.Lookup75Percent(grossVehicleWeight);
 			}
 
diff --git a/VectoCore/VectoCore/Models/Declaration/LookupData.cs b/VectoCore/VectoCore/Models/Declaration/LookupData.cs
index 0c2f1b7580c960ee13b5a9724dac13345424d642..75cd0f1eae59b471727126746b71dc1c2732c0a5 100644
--- a/VectoCore/VectoCore/Models/Declaration/LookupData.cs
+++ b/VectoCore/VectoCore/Models/Declaration/LookupData.cs
@@ -93,7 +93,7 @@ namespace TUGraz.VectoCore.Models.Declaration
 		protected static void NormalizeTable(DataTable table)
 		{
 			foreach (DataColumn col in table.Columns) {
-				table.Columns[col.ColumnName].ColumnName = col.ColumnName.ToLower().RemoveWhitespace();
+				table.Columns[col.ColumnName].ColumnName = col.ColumnName.ToLowerInvariant().RemoveWhitespace();
 			}
 		}
 	}
diff --git a/VectoCore/VectoCore/Models/Declaration/SteeringPumpBus.cs b/VectoCore/VectoCore/Models/Declaration/SteeringPumpBus.cs
index c65823f5d97482a4b22dfa4d01f0c2c3624b2a31..ac2f1af73f978c28d20fbbb3c818aea2a2f19fa1 100644
--- a/VectoCore/VectoCore/Models/Declaration/SteeringPumpBus.cs
+++ b/VectoCore/VectoCore/Models/Declaration/SteeringPumpBus.cs
@@ -101,8 +101,8 @@ namespace TUGraz.VectoCore.Models.Declaration {
 						Data[Tuple.Create(axleNumber, mission)] =
 							 new SteeringPumpTechnologyEntry() {
 									FullyElectric = !row.Field<string>("fullyelectric").Equals("0"),
-									TubingFactor = row.ParseDouble("tubing-"+mission.ToString().ToLower()),
-									AxleFactor = row.ParseDouble("axle-"+mission.ToString().ToLower())
+									TubingFactor = row.ParseDouble("tubing-"+mission.ToString().ToLowerInvariant()),
+									AxleFactor = row.ParseDouble("axle-"+mission.ToString().ToLowerInvariant())
 							};
 					}
 				}
diff --git a/VectoCore/VectoCore/Models/Declaration/WHTCCorrection.cs b/VectoCore/VectoCore/Models/Declaration/WHTCCorrection.cs
index 2123c256e8d19fbd1c3f05e0eeab53d7f6b1f9ed..941537a75c99b3269f2860575a08378f6b10b7d0 100644
--- a/VectoCore/VectoCore/Models/Declaration/WHTCCorrection.cs
+++ b/VectoCore/VectoCore/Models/Declaration/WHTCCorrection.cs
@@ -60,7 +60,7 @@ namespace TUGraz.VectoCore.Models.Declaration
 					if (mission.IsEMS() || !mission.IsDeclarationMission() || mission == MissionType.ExemptedMission) {
 						continue;
 					}
-					var values = table.Columns[mission.ToString().ToLower()].Values<string>().ToDouble().ToArray();
+					var values = table.Columns[mission.ToString().ToLowerInvariant()].Values<string>().ToDouble().ToArray();
 					Data[mission] = new Entry { Urban = values[0], Rural = values[1], Motorway = values[2] };
 				}
 			}
diff --git a/VectoCore/VectoCoreTest/Models/Declaration/DataAdapter/DeclarationAdapterCreateVocationalVehicleTest.cs b/VectoCore/VectoCoreTest/Models/Declaration/DataAdapter/DeclarationAdapterCreateVocationalVehicleTest.cs
index 169f6f2b96419dfb4a013bd52e5884dfefcb81bf..aff8f3b3c60afb3ae1fe149ef2d400e6cc8db1a4 100644
--- a/VectoCore/VectoCoreTest/Models/Declaration/DataAdapter/DeclarationAdapterCreateVocationalVehicleTest.cs
+++ b/VectoCore/VectoCoreTest/Models/Declaration/DataAdapter/DeclarationAdapterCreateVocationalVehicleTest.cs
@@ -53,7 +53,7 @@ namespace TUGraz.VectoCore.Tests.Models.Declaration.DataAdapter
 			helper.AddNamespaces(manager);
 
 			var vocational = nav.SelectSingleNode(XMLHelper.QueryLocalName(XMLNames.Component_Vehicle, XMLNames.Vehicle_VocationalVehicle));
-			vocational.SetValue(true.ToString().ToLower());
+			vocational.SetValue(true.ToString().ToLowerInvariant());
 			var modified = XmlReader.Create(new StringReader(nav.OuterXml));
 			
 			var dataProvider = xmlInputReader.CreateDeclaration(modified);