How does MEV work
Why MEV?
Today’s modern apartment buildings offer challenges to the ventilation system designer. Limiting noise ingress, wind effects, aesthetics and installation limitations have to be taken into account in addition to regulatory compliance and cost. MEV has less dependency on background ventilators, requires only a single discharge grille for a whole apartment and very often has smaller, easier to install ducts than systems designed around intermittent operating extract fans and background vents. Such benefits make MEV an increasingly popular method of providing adequate ventilation in such homes.How does it work?
Essentially the concept is to provide simultaneous, low level extraction from Kitchens, Bathrooms, Shower rooms, Utility rooms and WC’s to a central extract fan via a system of ductwork and grilles. The extracted air is then normally discharged to outside via a single duct and grille/cowl. Current Building regulation guidance, in the form of BRE Digest 398, requires such systems be designed to provide background extraction at a rate equating to approximately 0.5 air changes per hour based on the whole dwelling volume with the ability to boost by 25-50% for times when increased ventilation is required e.g. during cooking. Replacement air is normally able to be provided via structural air leakage with background ventilation openings like trickle vents not normally needed unless the home is built to extraordinarily airtight standards. This can be best demonstrated by referring to the table below which shows the very small building fabric air resistance an MEV system on boosted extraction would have to overcome in apartments of different levels of airtightness. As this type of system has to work 24 hours a day, 7 days a week, 365 days a year, low noise levels and reliability are critical.Relevant Literature & Documents
  | Brochure: Ventilation Solutions for Apartments and Communal Residences File size: 1.6 MB |
 | Brochure: Ventilation Solutions for the Decent Homes Standard File size: 1.1 MB |
 | Brochure: Ventilation Solutions for Housebuilders and Developers File size: 2.7 MB |
 | Installation and Maintenance Manual: Mechanical Extract Ventilation (MEVAC) Leaflet Number: 671381 - Mar-08 File size: 203 KB |
| | Installation and Maintenance Manual: Mechanical Extract Ventilation (MEVDC) Leaflet Number: 671382 - Dec-07 File size: 323 KB |
  | Link to page: Residential Product Applications |
You will require Adobe Reader to view the above PDF () documents. 
