Air changes (number)

The ratio of the amount of air of ventilated into a room over 1 hour divided by the volume of the room at an overpressure of 50 Pa.
n₅₀ air exchanges (requirement values):
For existing buildings: 7
Modern new building (HU): 5-10
Modern new building (DE): 2-6
Low energy building: 0.17-5
Passive house: 0.17-0.6