Public Function Format(ByVal Expression As Variant, Optional ByVal FormatString As Variant, _
              Optional ByVal FirstDayOfWeek As VbDayOfWeek = vbSunday, _
              Optional ByVal FirstWeekOfYear As VbFirstWeekOfYear = vbFirstJan1) As String
 
   Dim Hours As Long
 
   If IsDate(Expression) Then
      If InStr(1, FormatString, "[h", vbTextCompare) > 0 Then
         Hours = Fix(Round(CDate(Expression) * 24, 1))
         If Hours < 24 Then
            FormatString = Replace(FormatString, "[hh]", "hh", , , vbTextCompare)
            FormatString = Replace(FormatString, "[h]", "h", , , vbTextCompare)
         Else
            FormatString = Replace(FormatString, "[hh]", CStr(Hours), , , vbTextCompare)
            FormatString = Replace(FormatString, "[h]", CStr(Hours), , , vbTextCompare)
         End If
      End If
   End If
 
   Format = VBA.Format$(Expression, FormatString, FirstDayOfWeek, FirstWeekOfYear)
 
End Function