The age of air is the mean time taken for air molecules arriving within the domain to travel to the point of interest. It is a steady-state calculation.
You can request age of air to be calculated on the CFD tab after the main CFD simulation has completed as a separate operation. To do this click on the Calculate LMA tool.
After completing the Local Mean Age of Air (LMA) calculation the Air Change Effectiveness (ACE) tool is available. The air change effectiveness (ACE), is defined as the age of air that would occur throughout the room if the air was perfectly mixed, divided by the average age of air where occupants breathe. Because the average age of air exiting the room is identical to the age of air that would occur throughout the room if the indoor air were perfectly mixed, the ACE is also the exhaust-air age divided by the average age of air where occupants breathe. In practical terms, the ACE equals the effective ventilation rate at the breathing zone divided by the ventilation rate that would occur throughout the building with perfect mixing and at the same outdoor air supply. A short-circuiting flow pattern between the fresh air supply and return outlets, increases the room-air age and causes ACE to be less than unity. Perfect mixing results in an ACE of unity. Preferentially ventilating the breathing zone with outside air will cause the ACE to be greater than unity.
To calculate air change effectiveness use the ACE tool.
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