Practices

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Characteristics and performance of MVHR systems

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This meta-study, commissioned by Innovate UK as part of the Building Performance Evaluation (BPE) Programme, provides an overview of the performance and use of whole-house heat recovery ventilation (MVHR) systems in domestic projects.

 

It aims to:

  1. review the characteristics of installed systems in relation to air flow, system balance and compare to existing published guidelines, particularly those contained in the relevant Building Regulations documents;
  2. investigate, via surveys and interviews, the reasons for selecting MVHR as a ventilation strategy on a development and experience of MVHR systems in practice;
  3. review available monitored data to investigate the performance of houses with MVHR systems;
  4. determine the key features of MVHR systems with respect to the quality of their design and installation and commissioning procedures.

 

According to the authors, common problems identified 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. Furthermore, there was a lack of consideration of key issues at design and construction stages, including the function of the system, integration into the design, quality of installation and commissioning, control systems, and occupant guidance and understanding.

 

Despite these issues, the performance data suggests that overall the use of MVHR systems can result in better levels of ventilation in comparison to naturally ventilated houses. The average CO2 levels were reasonable; both average and peak levels were lower; and the environmental data suggests that more consistent temperature and relative humidity was achieved in dwellings with MVHR systems.

 

The full document is available to download at: http://www.fourwalls-uk.com/mvhr-meta-study/