"Other Space Used for Environmental Air" (Space above a suspended ceiling)

[Jon456]

A commercial tenant space has a suspended ceiling with return air ductwork for the HVAC. So the area above the suspended ceiling would normally be considered a "dead ceiling" (i.e., it's not a plenum space).

However, within this tenant space is a utility closet. And in the utility closet, there is no suspended ceiling: the utility closet is open all the way up to the building's roof. There are no HVAC supply or return registers in this closet. But if the utility closet door is open, then all the air in the space above the suspended ceiling is essentially connected to all the air in the space below the suspended ceiling. Basically, it's like having a suspended ceiling with some of the ceiling tiles permanently removed.

Would this change the classification of the space above the suspended ceiling as "Other Space Used for Environmental Air"?

 

[Fred B]

A commercial tenant space has a suspended ceiling with return air ductwork for the HVAC. So the area above the suspended ceiling would normally be considered a "dead ceiling" (i.e., it's not a plenum space).

However, within this tenant space is a utility closet. And in the utility closet, there is no suspended ceiling: the utility closet is open all the way up to the building's roof. There are no HVAC supply or return registers in this closet. But if the utility closet door is open, then all the air in the space above the suspended ceiling is essentially connected to all the air in the space below the suspended ceiling. Basically, it's like having a suspended ceiling with some of the ceiling tiles permanently removed.

Would this change the classification of the space above the suspended ceiling as "Other Space Used for Environmental Air"?

I wouldn't think so, the area that is referred to as space used for environmental air is like when the hvac uses the wall void between studs or floor joists as a air return rather than ducting it, same is true in like mobile home heating it has no return ducting it uses the space containing the furnace with a door vent opening for return air, making that area also space used for environmental air.

 

[kwired]

You still not using the space to move environmental air

 

[LarryFine]

I agree: no.