Everything you need to know about Mechanical Ventilation Heat Recovery
Good air quality and ventilation in our homes is essential to our health and wellbeing. MVHR, or Mechanical Ventilation with Heat Recovery is the most suitable and effective ventilation system for low energy and good health. But what exactly is MVHR and how much does it cost?
Mechanical Ventilation with Heat Recovery – the facts
Mechanical Ventilation with Heat Recovery is a ventilation system for the whole house that supplies and extracts air throughout the property. Heat recovery is an option used in domestic dwellings, and helps in the reduction of heating and cooling demands of buildings.
Typically around 73-95% of the heat in exhaust air is recovered by heat recovery systems. This has significantly improved the energy efficiency of buildings.
The idea and technology behind MVHR is fairly simple. It provides fresh, filtered air into the home, as well as providing heat between incoming and outgoing air, via a heat exchanger.
What does MVHR do?
The ways in which MVHR can help your home to be more healthy are what typically attract people to having it installed in theirs. You will expect:
- A delivery of constant fresh air
- Humidity and moisture to be well managed
- Helps get rid of mould
- A high standard of energy efficiency
- Solving any heat loss issues
Can MVHR heat a house?
Absolutely, yes. On colder days, the heat exchanger within the MVHR unit transfers the heat from the air leaving the building, into the incoming air.
An MVHR system plays an important part in retaining warmth without the stuffiness that can sometimes come with central heating.
The air is moved around the MVHR system using low energy fans. Filters are used to minimise any pollutants from entering your home from the outside, with different grades of filters available, depending on your external air quality in your area.
Is MVHR an ideal choice?
MVHR is a fantastic piece of technology. Its installation and design within your own home is paramount for quality usage and benefits. Operation needs to be quiet and efficient, so if it isn't designed properly, it can be noisy.
MVHR is ideal if you:
- Require a whole house ventilation solution
- You want a more energy efficient home
- You are doing a full renovation or building a new house
When is the level of airtightness with MVHR worthwhile?
MVHR can be installed in any building, but there is a rule that its use is not really justified unless the air permeability of the thermal envelope is at or below 3 air changes per hour when tested at 50 Pascal. (This is equivalent approximately to 3 m³/m².h @ 50 Pa for average dwellings).
Research has shown that MVHR ventilation could be used in less airtight homes (for example, even a fairly draughty home of 9 m3.h/m2 @50 Pa), as it would still have lower carbon emissions rate than natural ventilation. However, in very draughty homes (those that are higher or worse than 9 m3.h/m2 @50Pa) - the efficacy and efficiency of an MVHR will decrease.
What are the costs for having MVHR installed in my home?
As of September 9th 2022, the average installation cost of MVHR was £6,450 (for a domestic installation). The cost is inevitably higher with retrofit projects as opposed to new build developments, but this price includes all parts and the design of the system to fit your property, although you may find some companies may charge extra for those.
Commercial MVHR system installation will set you back more, typically being around £10,000 for the unit and a further £20-30m² for suitable ducting installation.
It is worth remembering...
If your home suffers with damp, condensation, or mould, you are going to find MVHR a worthwhile installation to keep these at bay. However, it is always worth remembering that it will not solve the root of the problem, which may be something you want to look into separately. MVHR is very effective, but it is not a cure for ongoing problems that you may already be aware of.
