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Intelligent Mechanical Extract Ventilation System (iMEV)

Passivent’s iMEV system 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.

There are two systems available to support the whole-house ventilation requirements of any particular dwelling ; iMEV Local which senses humidity change in rooms and allows greater extraction rate and iMEV Total which senses both humidity change in rooms and pressure differences in the system to allow greater extraction rates by increasing fan speed automatically.

iMEV Local

  • Senses humidity change in rooms and allows greater extraction rate.
  • Constant fan speed provides continuous low-level extraction resulting in lower energy costs.
  • Extraction is boosted automatically in rooms where needed by means of humidity sensitive extracts in each wet room.
  • Automatic – no occupant involvement necessary.
  • Quiet fan means less occupant disturbance.
  • Local automatic control keeps the system working as it should – extracting at high levels where needed.
  • Used in individual houses, apartments with one fan unit per flat, care homes and student accommodation.

iMEV Total

  • Senses both humidity change in rooms and pressure differences in the system to allow greater extraction rates by increasing fan speed automatically.
  • A constant pressure system is ideally suited to provide effective ventilation for larger buildings.
  • Pressure sensitivity within the system will increase fan speed.
  • Fully automatic control maintains effective ventilation throughout a building.
  • Ventilation is tailored to the needs of individual rooms or spaces.
  • Humidity sensitive extracts for wet rooms.
  • Zonal control minimises heat loss from areas where additional extraction is not required..
  • Quiet fan that reduces speed at night eliminates occupant disturbance.
  • Used in premises where individual spaces may require different controlled extraction rates, such as large dwellings, care homes or student accommodation.

Further information about the component parts of the iMEV system can be found on the Demand Controlled Extracts page and the Fans/Supply Air/Ducting & Terminals page.



Range Brochure


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For any questions or queries about our product ranges and the technical support services we can offer, please contact us using the form below.

Passivent is a division of Building Product Design Ltd.

Other subsidiaries include Glidevale Protect, a specialist in ventilation solutions, condensation control and energy efficiency across the built environment and Kingfisher Louvres, manufacturer of aluminium louvre systems.

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