atrium volume
The total interior volume of the largest atrium within a structure or module.
Atrium volume is the total cubic interior space enclosed by the largest atrium within a building. It measures only the space belonging to the atrium, and usually omits spaces contiguous with it such as rooms and corridors branching out from it.
An atrium is defined as a wide, continuous indoor space at least 5 floor levels high.
A volume of this kind is calculated from the building's own dimensions rather than measured, so it follows whichever outline the source used. A figure taken to the facade and one taken to the structure differ, and neither is wrong as long as the record says which.
It is not a floor area multiplied by a height. A building whose upper floors step back has less volume than that calculation gives, which is why the two figures disagree for most towers.