mvhr & DCMVHR

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"Insulation, insulation, insulation," has been our mantra to clients over many years, but now that highly insulated and airtight homes are becoming the norm, indoor air quality has become a prime concern.  A building that cannot breathe will be subject to condensation in wet rooms, leading to mould and other nasties.  Poor indoor air quality has led to a phenomenon that has come to be known as sick building syndrome.  If the indoor air quality is poor, the inhabitants will also suffer ailments associated with breathing, such as asthma.  The forthcoming amendment to the building regulations is likely to tighten the requirements for ventilation.  Opening a window will no longer suffice because that will defeat the purpose of having an energy efficient airtight building.  Efficient ventilation without heat loss will be necessary, and the best way to achieve this is through MVHR.


Mechanical ventilation with heat recovery draws warm, stale air from warm wet rooms like bathrooms and kitchens,  and puts it through a heat exchanger.  At the same time, fresh air is drawn into the building and is pre-warmed in the heat exchanger, then distributed through ducts in the ceiling or loft to rooms such as living rooms and bedrooms.  The effect is a comfortable home that feels fresh and breathable all the time as it operates 24/7 irrespective of whether there is a need to improve air quality, but you can set up a user profile to vary the circulation rate depending on your lifestyle.

Installing an MVHR system can sometimes reduce the size of heat pump required.

Homes with MVHR do not require trickle vents in the windows.


Demand Controlled Mechanical Ventilation with Heat Recovery works in a similar way to MVHR, but is more efficient than MVHR because it only operates as the need arises thanks to sensors that detect increased levels of carbon dioxide, humidity, or VOCs (volatile organic compounds/smells).  When unhealthy levels are detected, the system will operate to improve the air quality until safe levels are re-established.

As with MVHR, homes with DCMVHR do not have trickle vents in the windows.

All installation photographs on this web site are our own work, and are copyright.

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Borders Green Energy is a trading name of Borders Underfloor Heating Ltd

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Scotland, UK

01896 668667

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MVHR ducting diagram

Diagram of the ducting system we use for MVHR systems.