How does hybrid ventilation work?
Between natural ventilation and mechanical exhaust ventilation (MEV), hybrid ventilation is a recent concept that consists in using the components and sizing of natural ventilation ducts coupled with non-constant low-pressure mechanical assistance. Mechanical assistance is only used to supplement natural forces when necessary.
By natural forces we mean three different kinds of natural phenomena that cause the air mass to move.
- The first natural force is simply wind that can penetrate the dwelling through entrances and exists.
- The second natural force is the thermal draught where the airflow is produced by the density difference between the hot air and the cold air: the less dense hot air tends to rise whereas the denser cold air tends to go down.
- Last but not least is the aeraulic draught caused by the pressure difference linked to height: the lower upright pression creates a depression that enables the air to circulate in the dwelling.
The hybrid ventilation start is automatic; it can be activated by a temperature sensor, a wind vane or a pressure switch. Fresh air is admitted through the humidity-controlled air inlets located in the dry rooms (bedrooms and living room). The stale air is evacuated through the wet rooms (toilets, bathroom, kitchen) by humidity-controlled extraction grilles linked to the ventilation duct connected to the fan. The pressures generated by hybrid ventilation are comparable to those of natural ventilation, in the order of 5 to 15 Pa at the grilles.