In March 2016 a group of researchers from the The Mackintosh Environmental Architecture Research Unit (MEARU), Oxford Institute for Sustainable Development (OISD) and Fourwalls Consultants released the results of their meta study on MVHR systems in the UK.
The study revealed that most MVHR systems don’t perform as they were intended. It also flagged up a difference between standard systems and those designed and specified to Passivhaus standards, as their real performance reflected more their design values.
Here some excerpts of their findings:
Well designed, installed, maintained and used MVHR systems are able to make useful contributions to energy reduction and good ventilation. However, in practice achieving all these conditions is a challenge for the industry and many of the projects in the studies had a number of problems that would undermine these benefits.
Common problems included:
- Insufficient system air flow and system imbalance;
- Lack of appropriate airtightness;
- Poorly designed and installed ductwork;
- Lack of occupant handover and understanding;
- Inadequate maintenance, in particular filter cleaning or replacement.
In airtight homes, the importance of maintaining the ventilation provision is imperative and the consequences of failure may be more significant, and may have detrimental health implications for the occupants.