Intelligent Mechanical extract Ventilation (iMEV)

Intelligent Mechanical extract ventilation (iMEV)

Passivent iMEV is ‘intelligent’, in that it removes the need for any occupant interaction, automatically detecting rises in humidity and responding accordingly.

The system only increases extraction when required, so it uses much less energy as the central fan is not running at a higher speed unnecessarily. Heat loss is also reduced as iMEV relies on demand control (extraction when and where required); extraction is only increased in the areas where humidity has risen.

Two systems are available; iMEV Local which senses humidity change in rooms and allows greater extraction rate and iMEV Total which both senses humidity change in rooms and pressure differences in the system to allow greater extraction rates by increasing fan speed automatically.

iMEV Local

  • Constant fan speed means lower energy costs.
  • Humidity sensitive extract units for wet rooms.
  • Automatic - no occupant involvement necessary.
  • 24 hour condensation control.
  • Quiet fan running means less occupant disturbance.


iMEV Total

  • Automatic demand control maintains effective ventilation.
  • Humidity sensitive extract units for wet rooms.
  • Pressure sensitivity within the system will increase fan speed.
  • Zonal control minimises heat loss from areas where higher extract rates are not required.
  • Quiet fan running reduces speed at night meaning less occupant disturbance.