Thank you for your question.
The Ekol Crystal 8 stove will need an air vent in the room.
The official numbers on air vents are 550mm² per kW for stoves with output over 5kW.
So for the Crystal 8 you will need an air vent not less than 1650mm² (16.5cm²)
Most 125mm (5-inch) air vents are well in excess of this measurement.
Hope this helps?