Studio Plan in Austria

Hi! Here is my Studio and i wanted to ask you for some help. Would you change anything? The Room High at Controll Room (Regie) and recording Room (Aufnahme) is 3.50 meter and at the lobbie and the small corner office is 3.00 meter. at the top of the toilett i thought about having a place for the Ventilation. Please give me your advice! Thanx Manu