An elected upper house would eventualyl end up being a copy of an elected lower house with the same parties getting roughly equal shares of the two houses. Far more important is the basic question of WHY?
Why is there an upper house?
Why can't the lower house do that?
Once these questions are answered you can look at how to appoint members of the upper house. If you elect them then, in reality they are identical to the lower house and so not needed.
Paul.