MVHR (Mechanical ventilation with heat recovery) is a whole dwelling ventilation system that supplies and extracts air continuously at a low rate with the facility to be boosted as required meeting Building Regulations Part F . The unit is normally installed in the loft space or cupboard and rigid ducting supplies fresh filtered air to the habitable rooms and extracts stale polluted air from the ‘wet’ rooms. Supply and extract diffusers are fitted to the ceilings and are adjusted to balance the system. The unit incorporates a heat exchanger that tempers the incoming air before it is delivered to the habitable rooms.
The system can be controlled to boost speed when moisture is being generated (by bathing or cooking for instance) either
- Manually via single or multiple switches
- Automatically, typically via humidity or other sensors
These should be located in or near the wet rooms. Background ventilators in windows are not required with this system. For housebuilders, energy efficiency is still the most important specification factor when it comes to ventilation as they seek the most cost-effective way to achieve carbon reductions and reduce dwelling emission rates (DER). Specifying an MVHR unit that boasts low energy usage and high thermal efficiency is key to reducing a home’s DER. As consumers have become more informed of the health implications of Indoor Air Quality, MVHR is coming to the fore as a key ventilation solution.
