What is dMEV ventilation?


What is dMEV ventilation?

We take a lot of calls from private landlords, damp proofers, property managing agents, homeowners and builders for advice on the best type of extract fans for bathrooms, kitchens, utility rooms especially to combat or prevent black mould issues.

We exclusively recommend continual running extract fans also referred to as dMEV.

What is dMEV ventilation?

A decentralised Mechanical Extract Ventilation (d-MEV) system is a low energy, continuous running mechanical extract ventilation system designed to replace conventional intermittent bathroom fans and draw moisture laden air out of the wet rooms (bathrooms, kitchen and utility) providing a quieter and more efficient system. This technology is rapidly developing and extract fan performance can be monitored and recorded by data loggers for proof of performance……


















Particularly ideal for our private landlord market place to combat condensation and black mould issues and because running cost is so low at between £1.50 – £2.00 a year running cost, there is no need for tenants to worry about the electricity bill for the trade off of not having black mould!

  • Replaces conventional extractor fans 
  • Prevents condensation & mould growth
  • Silent running, 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 voltage 
  • 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
  • Ease of maintenance
  • Timer, humidity sensor and pullcord models
  • Up to 5 year warranty


Usually installed in kitchens and bathrooms through the wall or ceiling new or in replacement of the conventional fan extracting continuously at a normal low ventilation rate.

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

What is the differance between a MEV and a dMEV

The dMEV 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.

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 highly insulated dwellings e.g. <5ach@50Pa, background ventilators to 2500mm2 are required in all habitable rooms. If used in conjunction with a positive ventilation unit (PIV) there is no further requirement for window trickle vents.

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 are a number of control options available to increase the speed from pull-cord, own switch or light switch and Humidity sensor with timer run-on.

Not sure on what fans are suitable for your needs? Call us on 01329 235252 or email us and we will gladly provide you with the correct advice. Products held in stock available on free 2 – 3 day economy delivery or upgrade to next day delivery.

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