The extra space would allow the building of new offices for MEPs' assistants, many of whom currently share office space with MEPs when they are in Strasbourg, and provision of new communal toilets.
No seriously, we cannot have MEP's assisatnts sharig the same office as their boss, that just wouldn't do. According to the European Voice it appears the money will also be used to knock down some of the intergral MEP loo spaces and build communal loos.
This will be good in that paradise of Presidents I suppose to discover who indeed is the biggest swinging Dick in town. But do we really need to spend another great wad of cash, on loos?