Discount for sharing a room in rented student accommodation

My daughter is planning on moving in with 5 fellow students this autumn. 4 of her proposed house mates lived together last year and the two new girls will be sharing a double room with two single beds. Should they get a discount for sharing, (total cost of house is €420 per week) or is it reasonable for the girls with the single rooms to pay extra? Nothing signed or agreed as yet. I cannot find anthing on AAM or on Google to really help.

I think it depends on whether the room has a bathroom or whether it is a bigger sized room. Normally if a room is bigger or has a bathroom you pay more than you would for a normal sized room.

Due to the fact that they are sharing, they should both pay a reduced rate. How many bedrooms has the house got and how many are sharing ?

House has 5 bedrooms, 3 doubles and 2 singles. The room my daughter would be sharing would be the biggest. No ensuite but each room has a sink.

€420/week = €70/week/person assuming 6 persons

Option 1 or Option 2
D = €80 or €75
D = €80 or €75
S = €70 or €75
S = €70 or €75
T = €60 or €60
T = €60 or €60

Total = €420

Option 1 - If the Double rooms differ from the Single rooms in size etc
Let the students taking the Double rooms (D) pay €80/week - 2No. Students
Let the students taking the Single rooms (S) pay €70/week - 2No. Students
Let the students taking the Twin room \ Double Room (T) pay €60/week - 2 No. Students

Option 2 - If the Double rooms & Single rooms are of similar size etc
Let the students taking the Double rooms (D) pay €75/week - 2No. Students
Let the students taking the Single rooms (S) pay €75/week - 2No. Students
Let the students taking the Twin room \ Double Room (T) pay €60/week - 2 No. Students

That is a fair way to go. It should be internally agreed with all students.

In other words your daughter should pay €60/week no matter what

Thanks for your detailed reply. My view would be that the student getting the double rooms for single use are getting much better value at €80 or €75 than the sharing students that would be paying €120 in effect for their room. Electricity ,heat etc are all to be shared equally.

They have equal use of all the shared space too, the rent covers more than just their bedroom.
There is a good doc here, which while perhaps a bit ott to actually implement, is a good starting point. http://www.boards.ie/vbulletin/showthread.php?t=2054867603