Qto_DistributionChamberElementBaseQuantities Base quantities that are common to the definition of all occurrences of distribution chamber elements. IfcDistributionChamberElement IfcDistributionChamberElement GrossSurfaceArea Total gross area of the inner surface of the chamber, not taking into account openings such as for pipes, ducts, or cables. Q_AREA Gross Surface Area NetSurfaceArea Total net area of the inner surface of the chamber, subtracting any openings such as for pipes, ducts, or cables. Q_AREA Net Surface Area GrossVolume Total gross volume of the chamber, not taking into account any enclosed elements such as pipes, ducts, cables, or equipment. Q_VOLUME Gross Volume NetVolume Total net volume of the chamber, subtracting any enclosed elements such as pipes, ducts, cables, or equipment. Q_VOLUME Net Volume