Why do we need MVHR?

MVHR & Indoor Air Quality
Modern energy efficient houses are being built with ever increasing levels of airtightness (with a Passivhaus being an extreme example). This minimises the amount of energy lost through a leaky structure but without ventilation it would mean that the accumulation of humidity, VOCs and smells would make a house unliveable. Traditionally ventilation is provided by trickle vents and single hole-in-the-wall fans but this leads to heat loss as it is uncontrolled, unreliable and inefficient.

Mechanical Ventilation with Heat Recovery (MVHR) provides a continuous supply of fresh warmed air by extracting the warm, damp, smelly air from wet rooms and kitchen. This air is passed through a heat exchanger and exhausted to the exterior. Simultaneously, fresh air is drawn in from outside and passed through the heat exchanger in the opposite direction where it is warmed by the extract air going out.

The argument for MVHR is an economic one as it can provide fresh air with minimal heat loss, thus making a well insulated, airtight house habitable. However it is becoming increasing apparent that there is equally important case for maintaining Indoor Air Quality

(IAQ). The removal of stale damp air means condensation and mould are eliminated and the house is so much cleaner as all incoming air is filtered. We receive regular comments from occupants of houses with MVHR saying what huge difference it makes to IAQ and that it alleviates symptoms of asthma and eczema. Once you have lived in house with MVHR, you wouldn’t want to live in one without it.

CVC Direct Ltd
Unit 11, Bushell Business Estate, Lester Way, Wallingford, OX10 9DD
T 01491 836666