Mechanical Ventilation with Heat Recovery

Mechanical ventilation with heat recovery (MVHR) is a type of ventilation system that mechanically supplies and extracts air, recovering heat from outgoing stale air and using it to warm up incoming fresh air. This can greatly improve indoor air quality and energy efficiency.

MVHR systems can help to maintain a comfortable indoor climate, reduce energy costs, and improve indoor air quality by ensuring a continuous supply of fresh air. They are particularly beneficial in tightly sealed properties where traditional ventilation options are limited.

Technically, yes, you can install an MVHR unit in a loft. However, recent guidelines and energy efficiency standards suggest this may not be the best location for optimal performance. The loft can experience extreme temperature fluctuations, which can negatively impact the performance and efficiency of an MVHR unit. Furthermore, long intake ducts, which are likely when the unit is installed in the loft, can lead to more thermal loss and thus reduced heat recovery efficiency.

As per the UK's Standard Assessment Procedure (SAP 10.2), MVHR units placed in lofts could suffer performance penalties due to temperature fluctuations. The guidelines now suggest locating the unit in a place that is easily accessible for maintenance and close to an external wall to ensure the highest efficiency. It's often recommended to place your MVHR unit in a utility cupboard or a similar location nearer to an external wall. This setup allows for shorter intake ducts, reducing thermal loss and improving heat recovery efficiency.