With more buildings being built and a need to meet current building regulations new homes and commercial properties are becoming increasingly air tight. Whilst this is great news for the thermal efficiency of a property as there are no longer big gaps around doors, windows etc, it does pose another problem, the problems of ventilation. A property needs to “breathe”, it needs to have fresh air, the reasons for this being:-
- Controls condensation – by having air movement within the house it removes the moisture within the air. This moisture is created by cooking, showering, bathing, breathing and many other ways. If the property has no air flow then this moisture condenses on colder surfaces, typically in the corners of rooms, on windows, or areas where it has been less well insulated. This condensation can lead to mould which brings along with it its own health problems.
- Removes stale stagnant air from the property, air that has been hanging around a while can lead to respiratory problems.
- Removal of pollutants. These pollutants are generated by day to day living and without the means for them to disperse can lead to health issues. Main causes for these pollutants are things like hair sprays, deodorants, cleaning products, even new carpets give off pollutants. There are many sources for potentially harmful pollutants.
- Removal of unpleasant odours.
Above is just a few reasons that property needs to have regular air changes however with modern properties becoming more and more sealed for energy efficiency purposes air changes are not happening in the same way. If the aim is to be a completely sealed property, such as a Passivhaus, then the property maybe entirely sealed with virtually no air movement whatsoever.
To overcome these problems faced by modern construction methods there are a number of solutions. These being:-
A system where warm moist air is extracted from the bathrooms and kitchens of a property, ducted through to a heat exchanger which then transfers the heat to the incoming fresh air which is then ducted back out to your other living spaces within the property.
Mechanical Extract Ventilation, or MEV, provides continuous low level extraction from kitchens, bathrooms, shower rooms, utility rooms and toilets.
Whilst it is easiest to install a system as the property is being built it doesn’t mean that it can not be fitted to an existing property. The key to a good system is design and planning. In a new build property (residential or commercial) the ducting and siting of the MVHR unit can be considered at the design stage. As the ducting can be 3-5 inches in diameter, typically then routes for the ducting to take need to be carefully considered as you can’t just drill a 5 inch hole in a joist as that will seriously affect the structural integrity of the joist! Ducting doesn’t need to be round, you can get letter box shape ducting which in some cases allows for great flexibility. With an existing property MVHR can still be installed it just may be a tad more challenging to incorporate it into the existing fabric of the building but there is no reason why a well sealed home can’t have the same benefits that MVHR offers.
The installation of MVHR goes beyond just putting ducting and the units in place and connecting them up. The system needs to be balanced to get the right amount of airflow at the extract and supply points in the individual rooms, to do this specialised equipment is used, but by setting up the system correctly is means that you will be optimising performance whilst keeping the unit running as quietly as possible.
MVHR is a notifiable technology, similar to the installation of a new gas appliance or a re-wire of a house. What this really means is that local building control needs to be notified of the installation, this can be done in one of 2 ways, a local building control officer can be asked to attend the installation address to assess that the installation has been carried out properly. However the most common way is to use a company such as ourselves that have proved competence and are qualified to self certify our own installation.