Honest Jon's Guide To Selecting A Mechanical Ventilation System

Getting Hot Under the Collar

Overheating in domestic properties is becoming a serious – and largely unexpected – issue. Whole house mechanical ventilation systems provide one means of addressing this, but only if the resident is on side. If you are in anyway involved in the domestic ventilation market, you’ve probably noticed a spate of national news stories addressing the issue of overheating in new builds.  It seems we have succeeded in insulating and draught proofing our new properties to such an extent that many have become uncomfortably stuffy or hot to live in, especially during the summer periods. With last year being one of the warmest years on record, reportedly attributable to global warming, this problem is only set to worsen.

Why not just open the windows? I hear you cry. It sounds by far, the most sensible solution.

The problem with that eminently rational approach is that occupants are sometimes unable to open their windows wide enough or the windows are too small to make much difference to the temperature inside. Furthermore, some people are actually unwilling to open their windows for the sufficient time required to allow the heat to dissipate due to security, pollution and noise concerns, especially at night. Mechanical ventilation systems that residents understand and can control to meet their personal preferences and circumstances are a step forward in addressing this.

With this in mind, here is my guide to selecting a Mechanical Ventilation System:


1. Choose a whole house mechanically driven ventilation system such as Mechanical Extract Ventilation (MEV) or Mechanical Ventilation with Heat Recovery (MVHR). MEV units are designed to continuously extract waste air from a dwelling, to improve the indoor air quality and help prevent condensation and mould from developing. MVHR is seen as more advanced, as it combines mechanical extract ventilation with heat recovery. The extracted air is filtered and passed across a heat exchanger to transfer the otherwise wasted heat to the fresh, filtered supply air, which is consequently pre-warmed and then distributed to the living areas of a dwelling.– ideal for the cooler months.

2. For a resident to truly benefit, select an ‘easy to install’ mechanical ventilation system. It is very easy to forget that the vast majority of people in this country have never heard of an MEV or MVHR system before. Look to use systems that can be fitted in an easy--access cupboard or a utility room; this also makes it more straightforward to regularly maintain an MVHR unit’s filters. Also, most importantly, the system itself must be easy to operate and where possible look for units with the instructions attached to the unit permanently, rather than as a separate instruction leaflet which may get lost over time.

3. Consider providing an advanced ventilation system that puts residents in greater control over their indoor environment. For example our new MVHR HRX a-Q unit offers an intelligent wall mounted controller – the Bluebrain. Through advanced AMIE (Air Management for Indoor Environments) technology, the Bluebrain controller includes features such as digital humidity control, automated summer bypass and accurate system balancing enabling occupants to have direct control over managing the humidity levels in their home. By accurately measuring air humidity, the HRX-aQ’s extract speed automatically changes from background to boost as the level of humidity increases, thereby providing optimal ventilation performance.

4. Look at incorporating rigid duct sound attenuators into a whole house ventilation system. It is not only beneficial for home occupants but also helps meet Building Regulation recommendations. A good MVHR and ducting system that has been installed correctly shouldn’t cause unnecessary noise, but there is potential for sound to travel down the ducting from the fan, or from traffic noise if located close to busy roads and even from room-to-room-cross talk. Duct sound attenuators, like our Domus range which have been manufactured with Microban® protected foam to protect against microbial growth, effectively absorb sound over a range of audible frequencies.

5. Lastly and no means least, make sure the MVHR system has a 100% summer bypass facility, to stop the unit from supplying pre-warmed air into the home during the summer and possibly night time periods. Opting for more advanced models which allow for automated bypass control by room temperature sensing or programmed time settings enables residents to set their own preferences depending on what they consider to be a comfortable indoor air environment. For convenience, this control should be a separate unit – not part of the MVHR unit – so it can be accessed readily.