What is d-MEV

What is a Decentralised Mechanical Extract Fan (d-MEV)

A decentralised Mechanical Extract Ventilation (d-MEV) system is a low energy, continuous Mechanical Extract Ventilation system designed to replace conventional bathroom fans and draw moisture laden air out of the wet rooms such as bathrooms and utility rooms, providing a quieter and more efficient system.

  • Replaces conventional extractor fans 
  • Prevents condensation & mould growth
  • App controlled models available
  • Easy to maintain
  • Constant volume, continuously running extract ventilation 
  • Fitted with low watt DC motors for minimum energy consumption
  • Incredibly quiet running below 20 dB(A)
  • SAP Appendix Q eligible achieving 
  • Low Specific Fan Power 
  • Low voltage version available
  • Complies with Building Regulations, Part F, for System 3 - Continuous Mechanical Extract
  • One fan for all situations
  • Ease of installation and commissioning of speed settings
  • Highly versatile, can be installed into walls and ceilings
  • Timer, humidity sensor and pullcord models
  • Manufactured in the UK
  • Up to 5-year warranty


A d-MEV unit is usually installed in a bathroom ceiling or wall, they are in replacement of the conventional fan extracting continuously a low rate of ventilation. Fresh air from outside is supplied by a Pozidry Positive Input Ventilation (PIV) unit or window vents.

The fans run continuously at near silent levels providing a simple and effective form of extract ventilation.

What is the difference between a MEV and a d-MEV?

The d-MEV system works under the same principle as whole house Mechanical Extract Ventilation (MEV) but with individual fan installed directly in the kitchen and every wet room in the property. This sleek and stylish bathroom extract fan is quiet, energy efficient with 2 speed continuous ventilation system.

Building Control

The current Building Regulations Approved Document F gives examples of four main methods of ventilation with the most popular being System 3, continuous mechanical extract ventilation.

This can be achieved using a decentralised individual fans (dMEV) in the ‘wet’ rooms.

In dwellings that are highly insulated, e.g. <5ach@50Pa, background ventilators to 250mm2 are required in all habitable rooms. If d-MEV is used in connection with Positive Input Ventilation (PIV), window trickle vents are not required.

D-MEV systems comply with BRE digest 398 under continuous mechanical extract ventilation and meets the minimum fan power requirement of 0.5w/l/s in the ‘Domestic Building Services Compliance Guide’ (2010 edition).


There is a range of control options available including PIR sensors, humidity sensors and switched live from light switches.