Controlled mechanical ventilation (CMV) can be a simple or double flow system. It ensures optimal air renewal and comfort in the home when combined with appropriate insulation.

Why controlled mechanical insulation?

The best choice of ventilation is one that is integrated into a general comfort and savings approach. Ventilating the home properly and economically requires a compromise: renewing air necessary for well-being and health of the occupiers and evacuating excess steam. Permanent controlled mechanical ventilation is the best solution. 
 

The air renewal rate is controlled and the home is permanently ventilated, all year round, in all the rooms. Furthermore, the operating cost of controlled mechanical ventilation is very low. It always produces heating and maintenance savings for the building.

What is a single flow or double flow CMV?

CMV extracts stale air. Clean air enters through inlets located above the windows. When the clean air is also extracted by ducts, this CMV is called a double flow system (incoming air / outgoing air).

Single flow CMV

The outside air enters through air vents located in the main rooms, crosses the air and is then rejected outdoors via service areas (bathrooms, kitchens) thanks to a ventilator block. This can be hidden in the loft.
There are two types of single flow CMV.

  • self-adjustable CMV guarantees constant air flow regardless of outside and inside humidity conditions.
  • hygro-adjustable or “smart” CMV automatically adapts the air flow to occupiers’ needs according to variations in the humidity rate.

Double flow CMV

The principle is identical to the single flow CMV. The presence of an exchanger recovers the heat from extracted air to “warm” incoming outside air. This technique helps to optimise air renewal and save energy.
With this configuration, effective insulation, air tight walls, optimised ventilation produce comfort, energy savings and reduced CO2 emissions.

How to choose?

Double flow CMV is more complex to install and requires more complicated maintenance. It is also more expensive. 
Double flow CMV is particularly recommended if it is not possible to open windows owing to noise, olfactory pollution or possibilities of intrusion.

Is a vapour barrier necessary?

The vapour barrier prevents steam from crossing and stagnating in the walls of the house. Factor Sd is the reference indicator for vapour barriers. The higher the Sd factor, the less steam is let through.

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