Effects of height fire source in CFAST code about cfast HOT 2 CLOSED

You have a 4.5 m tall compartment with 4 air changes per hour of ventilation and a door that is 2.2 m tall. If the fire is at the floor, then it will always see oxygen entering via bi-directional flow through the doorway. If you put the fire high enough up in the compartment, then once the layer grows down to the height of the fire, the fire will no longer see any fresh air entering via the doorway. Check your ouptuts to see if this is what is happening, i.e., are you seeing lower temperatures because the fire has become viatiated and is not releasing as much heat as when it is lower in the compartment.

from cfast.

Dear Floyd,
I checked the outputs, you are right, certainly because the oxygen below to the base of fire is not included in the correlations of CFAST and less oxygen is available for the combustion.
So, the results (HRR, temperature...) are lower when the base of the fire is higher.
Regards,
Murat

from cfast.