ANSI/ASHRAE Standard 62-2001, Ventilation for Acceptable IndoorAir Quality, prescribes ventilation rates for commercial and institutionalbuildings. Historically, Standard 62 required both zone- andsystem-level calculations for the design of multiple-zone ventilationsystems, such as single-path constant volume and VAV systems. Unfortunately,without clear calculation procedures, system-level calculationsfrequently were misinterpreted or ignored by designers. As a result,many multiple-zone systems were underventilated.