A mechanical ventilation with heat recovery (MVHR) system can be the ideal solution for many homes, offices, and other buildings. Good ventilation is essential in enclosed areas where people live and work, and the heat recovery element of the system can help to improve energy-efficiency.
Without adequate ventilation, homes or other properties can be prone to damp and mould caused by condensation. This can affect the fabric of the property and also poses a significant health risk. Additionally, pollutants and allergens can build up which could be detrimental to the health of anyone in and around the premises, particularly those who have asthma or other respiratory problems.
There are many different ways to ventilate a property. Passive or natural ventilation requires no machinery and relies on natural air-flow through vents, air bricks, windows, doors and the small cracks and holes that exist in every building. This may be adequate in some cases but it is also highly reliant on outdoor conditions and might not always be sufficient, particularly in properties that have high levels of moisture or pollutants.
The simplest mechanical ventilation option is to fit an extractor fan in rooms such as bathrooms and kitchens. This can give natural air-flow a helping hand but again has limitations as it does not ensure constant air-flow throughout the building. Other options include supply-only mechanical ventilation, which uses motors and fans to draw fresh air into the building, with the extra pressure it brings producing the air-flow. The opposite approach extracts stale air from the building, with fresh air coming in to take its place.
Balanced systems use a combination of these methods, extracting moist, stale air out while drawing fresh air into the building.
As the name suggests, a mechanical ventilation with heat recovery (MVHR) system combines balanced mechanical ventilation and a heat recovery. Moisture-laden air is continually drawn from the wet rooms of the house Kitchen, bathroom, utilitie, Wc and ensuites. There may be a level of control, which allows you to change from a constant ‘trickle’ to 'boost' either manually or automatically when there are higher levels of moisture, such as when cooking or bathing.
At the same time, fresh air is drawn in from the outside. This air is filtered so there will be fewer impurities, which could include allergens, pollen and pollutants. The heat from the extracted stale and moist air is drawn out in a heat exchange unit and then transferred to the fresh air brought into the house. This is supplied into the ‘living’ areas of the house, including bedrooms and living rooms. The effect is to achieve good levels of ventilation, maintain a regular, controlled humidity and improve energy-efficiency by recycling heat.
When it comes to ventilation systems, there is no such thing as a one-size-fits-all solution. As mentioned, there are many different options and the best one for you will depend on various factors, including the type and size of your property, its climate, moisture levels, air-tightness and energy-efficiency.
If you have decided that a full MVHR system is right for your situation, it’s vital that it is properly commissioned and installed. The concept behind MVHR might be simple but the planning and installation can be quite complex. The vents, ductwork and other elements need to be correctly positioned and connected and the whole system should be tailored to the shape, size and other qualities of the building.
If this is part of the construction or renovation of a property, or you are planning a self-build, it makes sense to incorporate your MVHR system into the design of the house from the initial planning stages. This can help you comply with building regulations, as well as improving the functionality of the building. In an existing home or other building, highly-skilled and qualified installers can survey the property and help to design a bespoke solution. This can maximise the efficiency of the heat recovery and ventilation elements, while also reducing noise, mechanical vibration and air turbulence problems.
Every property is unique and every MVHR system should be too.
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