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Mechanical ventilation heat recovery keeps heat inside whilst ventilating your property.


A Mechanical Ventilation Heat Recovery unit can be utilised in small properties, flats or passive houses. They can also be docked to other renewable heating technologies in larger buildings, as isoenergy did so successfully with the ground source heat pump in Whitbread's award winning Green Hotel in Burgess Hill.

All MVHR units not only gather and redistribute heat around a building but also purify and filter the air in a property. This reduces allergens, smells and humidity in addition to providing heating or cooling.

MVHR units are ideal for social housing, flats or assisting large scale commercial projects.

How it works

A Mechanical Ventilation Heat Recovery unit operates by recovering the heat produced within a property from lighting, domestic appliances, showers, bathrooms, utility rooms etc. This recovered heat is then used to produce hot water, heating or cooling and in larger units, simultaneous heating and cooling.

Energy is transferred within the MVHR unit via a counter-current heat exchanger. Cool purified air is injected from outside and stale air is ejected from the building. Areas with large heat output or occupancy are ideal for extraction points, such as kitchens or bathrooms, whereas communal or living areas such as bedrooms or living rooms are best suited for injected clean air.

High levels of insulation and a passive house with an air tight design, help optimise an MVHR unit.


MVHR systems are increasingly important in modern buildings as the standards for air-tightness and thermal efficiency are progressively increased. In modern buildings, there may well not be enough natural ventilation without mechanical assistance. In older buildings, MVHR will only be worthwhile if the building was built to a high standard of air-tightness. In reality, this is unlikely to be the case in this country.

Small Flats and Social Housing
Small units, such as the Nilan VP18 are ideal for individual flats. They have a 180-litre hot water cylinder and an optional heat exchanger which allows for the external heating of hot water for use in conjunction with radiators and/or underfloor heating. The unit can also be delivered with a cooling feature, where the incoming fresh filtered air is cooled using the exhaust air to heat the hot water.

Passive Houses
Passive house standard buildings have highly effective thermal insulation and are airtight. These houses save energy and have extremely low energy costs. As more and more houses are constructed as passive houses, mechanical ventilation systems are becoming essential and provide the necessary ventilation whilst ensuring standards of comfort will not be compromised.

Mechanical ventilation in large or commercial properties
In a large scale property, such as one of our previous projects, a Whitbread 'Green Hotel', Isoenergy include a much bigger MVHR unit. These larger units extract humid air from bathrooms and unwanted heat in kitchens and redistribute it around the building. This will help to support the GSHP that provides the majority of the building’s heating and hot water.

Cub Houses and isoenergy
Cub homes are a unique and innovative ready-made modular housing concept, designed for quick and efficient delivery of a completely carbon neutral home.

Isoenergy has been commissioned to install MVHR systems in Cub homes, enabling them to be the first to achieve a pre-issued 5 star BRE certificate for an offsite constructed modular housing concept.




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