Most green builders include some type of mechanical ventilation system in every home they build. (greenbuildingadvisor.com)
A permanent code - compliant mechanical ventilation system must be installed in every air - tight house and building. (energyvanguard.com)
So notwithstanding the name Passive House, there is a very active mechanical ventilation system with heat recovery, bringing in fresh air all the time. (treehugger.com)