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East Midlands Energy Efficiency

Natural Ventilation

Natural ventilation occurs when air enters the building through openings to the outside world.  These could be open doors, opening windows or specifically designed vents.  If mechanical extraction fans are used without supply fans, the building is still naturally ventilated for energy assessment purposes.

The amount of natural ventilation that occurs in a building is measured through air-tightness testing.  This gives a values for the air permeability or air-tightness of the building which can be used to calculate the energy used to condition (warm up or cool down) the air entering the building.

Related Terms

Ventilation systems

Extraction systems

Mechanical ventilation

Mixed-mode ventilation